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Research involving Lowell Observatory staff 2016
(All publications)

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Years: 2016 Bottom

    2016

  1. Telesco, C., Sparks, W., Zhao, B., et al., (including Grundy, W.), 2016, AGUFM, P11C-1873, IMPS, A Static-Optics Application of Full-Stokes Spectropolarimetry to Search for Extraterrestrial Biosignatures
    Optical spectropolarimetry holds great promise in the search for extraterrestrial life. In particular, the detection of circular polarization can indicate chirality, a signature of biological significance. We describe an on-going effort to implement the full-Stokes (I, Q, U, V), static-optics concept for optical spectropolarimetry described by Sparks et al. [App. Optics, 51, 5495 (2012)]. Our early breadboard embodiments of the concept demonstrate its simplicity and indicate its potential for space missions in which a compact design with no moving parts is crucial to achieve the mission goals. We describe the instrument, called the Integrated Miniature Polarimeter and Spectrograph (IMPS), and consider one example for its deployment: a mission to land on an outer solar system body such as Europa.
  2. Buratti, B., Stern, A., Moore, J., et al., (including Grundy, W.), 2016, AGUFM, P42A-01, New Horizons Results at Charon
    The New Horizons Spacecraft encountered dwarf planet Pluto and its system of moons on July 15, 2015 for the first detailed study of a Kuiper Belt Object (1). Pluto possesses a system of at least 5 moons, including Charon, which is the largest moon in relation to its primary, comprising 12% of the mass of Pluto. The results from the flyby show a world that has undergone a large resurfacing event on at least one of its hemispheres, perhaps from differentiation and subsequent freezing of a subsurface ocean. Charon has a complex system of faults, and regions of various ages based on crater counting statistics. It has no evidence for recent or ongoing geologic activity as Pluto does. Its visible geometric albedo is 0.410.02, with normal reflectances ranging from 0.2-0.7. A few isolated brighter areas exist. A northern polar cap of low-albedo red material may be formed from a newly discovered process in the Solar System: the capture of methane from Pluto's atmosphere and subsequent polymerization and accumulation of a complex lag deposit (2). Unlike Pluto, which has a surface covered primarily of methane and nitrogen, Charon's surface is composed of water ice, along with NH3-ice in some form (3). The substantial relief on the moon implies that ice extends below the surface. The bulk density of Pluto and Charon are similar (1). This result implies that if Charon was formed from an impact and reaccretion event involving Pluto and a second body (4), it is unlikely the two bodies were fully differentiated prior to the event. (1) Stern, S. A. et al. (2015). Science 350, 292. (2) Grundy, W. M. et al. (2016). Manuscript accepted at Nature. (3) Grundy, W. M. et al. (2016). Science 351, 1283. (4) Canup, R. M. (2011). Astron. J. 141, 35. Funded by NASA.
  3. Schwamb, M., Fraser, W., Bannister, M., et al., (including Thirouin, A.), 2016, AGUFM, P42A-02, Colours of the Outer Solar System Origins Survey (Col-OSSOS): New Insights into Kuiper belt Surfaces
    The icy planetesimals of the Kuiper belt inform our knowledge about the growth of planetary embryos and our Solar System's dynamical history. The majority of the known Pluto-sized Kuiper belt objects (KBOs) are bright enough for their surfaces to be studied through optical and infrared spectroscopy. But for the typical smaller r mag > 22 mag KBOs, we must rely on what colors reveal by proxy, and this picture of Kuiper belt surfaces remains incomplete. Previous studies in this size range examined the hodgepodge set of KBOs discovered by surveys with varying and sometimes unknown detection biases that make it challenging to explore the true frequency of surface colors within the Kuiper belt. The Colours of the Outer Solar System Origins Survey (Col-OSSOS) aims to explore and explain the compositional variety within the Kuiper belt through near simultaneous u, g,r and J colors with the Gemini North Telescope and the Canada-France-Hawaii Telescope. The survey targets KBOs brighter than 23.6 r' mag ( 50-300 km) found by the Outer Solar System Origins Survey (OSSOS). With Col-OSSOS, we have a set of colors measured for a KBO sample discovered in a brightness limited survey, with a well-measured detection efficiency. Col-OSSOS will provide a compositional-dynamical map of the Kuiper belt in which to study the end of stages of Neptune migration and the conditions of the early planetesimal disk where these small icy bodies formed. We will give an overview of Col-OSSOS and an update on the program's current status. We will present the photometry from the first 30 KBOs studied from the first complete OSSOS block and examine the implications for Kuiper belt surfaces. We derive the observed and debiased ratio of neutral to red KBOs, measure the masses of the three color populations within the Kuiper belt (the red and neutral dynamically excited population and the red cold classical belt), and explore the radial color distribution in the primordial planetesimal disk before Neptune migration.
  4. Spencer, J., Stern, A., Olkin, C., et al., (including Grundy, W.), 2016, AGUFM, P54A-01, The Colors of Pluto: Clues to its Geological Evolution and Surface/Atmospheric Interactions
    New Horizons images of Pluto reveal a remarkably colorful world. In many places color corresponds closely with geology, while elsewhere there is little correlation, suggesting the colors result from a superficial coating. Color/color plots show that some parts of the surface are colored by simple linear mixtures of two components, while more complex mixing of multiple components is required elsewhere. Color shows striking correlation with latitude, though there are equally striking exceptions to that rule. Taken together with other New Horizons data sets, the color images paint a picture (literally) of the complex interplay of geology and insolation-driven atmospheric processes.
  5. Moore, J., Howard, A., Umurhan, O., et al., (including Grundy, W.), 2016, AGUFM, P54A-03, Bladed Terrain on Pluto: Possible Origins and Evolutions
    Pluto's Bladed Terrain (centered roughly 20N, 225E) covers the flanks and crests of the informally named Tartarus Dorsa with numerous roughly aligned blade-like ridges oriented North-South; it may also stretch considerably farther east onto the non-close approach hemisphere but that inference is tentative. Individual ridges are typically several hundred meters high, and are spaced 5 to 10 km crest to crest, separated by V-shaped valleys. Many ridges merge at acute angles to form Y-shape junctions in plan view. The principle composition of the blades themselves we suspect is methane or a methane-rich mixture. (Methane is spectroscopically strongly observed on the optical surfaces of blades.) Nitrogen ice is very probably too soft to support their topography. Cemented mixtures of volatile and non-volatile ices may also provide a degradable but relief supporting "bedrock" for the blades, perhaps analogous to Callisto. Currently we are considering several hypotheses for the origins of the deposit from which Bladed Terrain has evolved, including aeolian disposition, atmospheric condensation, updoming and exhumation, volcanic intrusions or extrusions, crystal growth, among others. We are reviewing several processes as candidate creators or sculptors of the blades. Perhaps they are primary depositional patterns such as dunes, or differential condensation patterns (like on Callisto), or fissure extrusions. Or alternatively perhaps they are the consequence of differential erosion (such as sublimation erosion widening and deepening along cracks), variations in substrate properties, mass wasting into the subsurface, or sculpted by a combination of directional winds and solar isolation orientation. We will consider the roles of the long-term increasing solar flux and short periods of warm thick atmospheres. Hypotheses will be ordered based on observational constrains and modeling to be presented at the conference.
  6. Thirouin, A., Moskovitz, N., Binzel, R., et al., (including Burt, B.), 2016, AJ, 152, 163, The Mission Accessible Near-Earth Objects Survey (MANOS): First Photometric Results
    The Mission Accessible Near-Earth Objects Survey aims to physically characterize sub-km near-Earth objects (NEOs). We report the first photometric results from the survey that began in 2013 August. Photometric observations were performed using 1-4 m class telescopes around the world. We present rotational periods and light curve amplitudes for 86 sub-km NEOs, though in some cases only lower limits are provided. Our main goal is to obtain light curves for small NEOs (typically, sub-km objects) and estimate their rotational periods, light curve amplitudes, and shapes. These properties are used for a statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller objects are more spherical than larger ones. We also report seven NEOs that are fully characterized (light curve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are objects fully characterized, with v NHATS 12 km s-1, and a rotational period P > 1 hr. Assuming a similar rate of object characterization as reported in this paper, approximately 1230 NEOs need to be characterized in order to find 100 viable mission targets.
  7. Bannister, M., Alexandersen, M., Benecchi, S., et al., (including Grundy, W.), 2016, AJ, 152, 212, OSSOS. IV. Discovery of a Dwarf Planet Candidate in the 9:2 Resonance with Neptune
    We report the discovery and orbit of a new dwarf planet candidate, 2015 RR245, by the Outer Solar System Origins Survey (OSSOS). The orbit of 2015 RR245 is eccentric (e = 0.586), with a semimajor axis near 82 au, yielding a perihelion distance of 34 au. 2015 RR245 has g-r=0.59+/- 0.11 and absolute magnitude {H}r=3.6+/- 0.1; for an assumed albedo of p V = 12%, the object has a diameter of 670 km. Based on astrometric measurements from OSSOS and Pan-STARRS1, we find that 2015 RR245 is securely trapped on ten-megayear timescales in the 9:2 mean-motion resonance with Neptune. It is the first trans-Neptunian object (TNO) identified in this resonance. On hundred-megayear timescales, particles in 2015 RR245-like orbits depart and sometimes return to the resonance, indicating that 2015 RR245 likely forms part of the long-lived metastable population of distant TNOs that drift between resonance sticking and actively scattering via gravitational encounters with Neptune. The discovery of a 9:2 TNO stresses the role of resonances in the long-term evolution of objects in the scattering disk and reinforces the view that distant resonances are heavily populated in the current solar system. This object further motivates detailed modeling of the transient sticking population.
  8. Herrmann, K., Hunter, D., Zhang, H., et al., 2016, AJ, 152, 177, Mass-to-light versus Color Relations for Dwarf Irregular Galaxies
    We have determined new relations between UBV colors and mass-to-light ratios (M/L) for dwarf irregular (dIrr) galaxies, as well as for transformed g - r. These M/L to color relations (MLCRs) are based on stellar mass density profiles determined for 34 LITTLE THINGS dwarfs from spectral energy distribution fitting to multi-wavelength surface photometry in passbands from the FUV to the NIR. These relations can be used to determine stellar masses in dIrr galaxies for situations where other determinations of stellar mass are not possible. Our MLCRs are shallower than comparable MLCRs in the literature determined for spiral galaxies. We divided our dwarf data into four metallicity bins and found indications of a steepening of the MLCR with increased oxygen abundance, perhaps due to more line blanketing occurring at higher metallicity.
  9. Nimmo, F., Hamilton, D., McKinnon, W., et al., (including Grundy, W.), 2016, Natur, 540, 94, Reorientation of Sputnik Planitia implies a subsurface ocean on Pluto
    The deep nitrogen-covered basin on Pluto, informally named Sputnik Planitia, is located very close to the longitude of Plutos tidal axis and may be an impact feature, by analogy with other large basins in the Solar System. Reorientation of Sputnik Planitia arising from tidal and rotational torques can explain the basins present-day location, but requires the feature to be a positive gravity anomaly, despite its negative topography. Here we argue that if Sputnik Planitia did indeed form as a result of an impact and if Pluto possesses a subsurface ocean, the required positive gravity anomaly would naturally result because of shell thinning and ocean uplift, followed by later modest nitrogen deposition. Without a subsurface ocean, a positive gravity anomaly requires an implausibly thick nitrogen layer (exceeding 40 kilometres). To prolong the lifetime of such a subsurface ocean to the present day and to maintain ocean uplift, a rigid, conductive water-ice shell is required. Because nitrogen deposition is latitude-dependent, nitrogen loading and reorientation may have exhibited complex feedbacks.
  10. Hamilton, D., Stern, S., Moore, J., et al., (including Grundy, W.), 2016, Natur, 540, 97, The rapid formation of Sputnik Planitia early in Pluto's history
    Pluto's Sputnik Planitia is a bright, roughly circular feature that resembles a polar ice cap. It is approximately 1,000 kilometres across and is centred on a latitude of 25 degrees north and a longitude of 175 degrees, almost directly opposite the side of Pluto that always faces Charon as a result of tidal locking. One explanation for its location includes the formation of a basin in a giant impact, with subsequent upwelling of a dense interior ocean. Once the basin was established, ice would naturally have accumulated there. Then, provided that the basin was a positive gravity anomaly (with or without the ocean), true polar wander could have moved the feature towards the Pluto-Charon tidal axis, on the far side of Pluto from Charon. Here we report modelling that shows that ice quickly accumulates on Pluto near latitudes of 30 degrees north and south, even in the absence of a basin, because, averaged over its orbital period, those are Pluto's coldest regions. Within a million years of Charon's formation, ice deposits on Pluto concentrate into a single cap centred near a latitude of 30 degrees, owing to the runaway albedo effect. This accumulation of ice causes a positive gravity signature that locks, as Pluto's rotation slows, to a longitude directly opposite Charon. Once locked, Charon raises a permanent tidal bulge on Pluto, which greatly enhances the gravity signature of the ice cap. Meanwhile, the weight of the ice in Sputnik Planitia causes the crust under it to slump, creating its own basin (as has happened on Earth in Greenland). Even if the feature is now a modest negative gravity anomaly, it remains locked in place because of the permanent tidal bulge raised by Charon. Any movement of the feature away from 30 degrees latitude is countered by the preferential recondensation of ices near the coldest extremities of the cap. Therefore, our modelling suggests that Sputnik Planitia formed shortly after Charon did and has been stable, albeit gradually losing volume, over the age of the Solar System.
  11. Reddy, V., Sanchez, J., Bottke, W., et al., (including Thirouin, A., Moskovitz, N.), 2016, AJ, 152, 162, Physical Characterization of 2 M Diameter Near-Earth Asteroid 2015 TC25: A Possible Boulder from E-type Asteroid (44) Nysa
    Small near-Earth asteroids (NEAs) (<20 m) are interesting, because they are progenitors for meteorites in our terrestrial collection. The physical characteristics of these small NEAs are crucial to our understanding of the effectiveness of our atmosphere in filtering low-strength impactors. In the past, the characterization of small NEAs has been a challenge, because of the difficulty in detecting them prior to close Earth flyby. In this study, we physically characterized the 2 m diameter NEA 2015 TC25 using ground-based optical, near-infrared and radar assets during a close flyby of the Earth (distance 128,000 km) in 2015 October 12. Our observations suggest that its surface composition is similar to aubrites, a rare class of high-albedo differentiated meteorites. Aubrites make up only 0.14% of all known meteorites in our terrestrial meteorite collection. 2015 TC25 is also a very fast rotator with a period of 133 6 s. We combined the spectral and dynamical properties of 2015 TC25 and found the best candidate source body in the inner main belt to be the 70 km diameter E-type asteroid (44) Nysa. We attribute the difference in spectral slope between the two objects to the lack of regolith on the surface of 2015 TC25. Using the albedo of E-type asteroids (50%-60%) we refine the diameter of 2015 TC25 to 2 m, making it one of the smallest NEAs ever to be characterized.
  12. Jao, W., Nelan, E., Henry, T., et al., (including Franz, O., Wasserman, L.), 2016, AJ, 152, 153, Cool Subdwarf Investigations. III. Dynamical Masses of Low-metallicity Subdwarfs
    We report dynamical mass measurements for the components of the previously known double-lined spectroscopic subdwarfs G 006-026 B and C using the Fine Guidance Sensors on the Hubble Space Telescope. To build the empirical mass-luminosity relation for low-metallicity subdwarfs, we collect four other subdwarf systems with dynamical masses that we compare to theoretical models for various metallicities on the mass-luminosity relation. For most stars, they fall in the regions where the models predict them to be low metallicity. This effort highlights the scarcity of dynamical masses for subdwarfs, and that much work remains to be done to improve the mass errors and metallicity measurements of low-mass subdwarfs in our Galaxy.
  13. Benedetti-Rossi, G., Sicardy, B., Buie, M., et al., (including Thirouin, A., Wasserman, L., Levine, S., Skiff, B.), 2016, AJ, 152, 156, Results from the 2014 November 15th Multi-chord Stellar Occultation by the TNO (229762) 2007 UK126
    We present results derived from the first multi-chord stellar occultation by the trans-Neptunian object (229762) 2007 UK126, observed on 2014 November 15. The event was observed by the Research and Education Collaborative Occultation Network project and International Occultation Timing Association collaborators throughout the United States. Use of two different data analysis methods obtain a satisfactory fit to seven chords, yielding an elliptical fit to the chords with an equatorial radius of R={338}-10+15 km and equivalent radius of {R}{eq}={319}-7+14 km. A circular fit also gives a radius of R={324}-23+30 km. Assuming that the object is a Maclaurin spheroid with indeterminate aspect angle, and using two published absolute magnitudes for the body, we derive possible ranges for geometric albedo between {p}V={0.159}-0.013+0.007 and {p}R={0.189}-0.015+0.009, and for the body oblateness between ={0.105}-0.040+0.050 and ={0.118}-0.048+0.055. For a nominal rotational period of 11.05 hr, an upper limit for density of = 1740 kg m-3 is estimated for the body.
  14. Williamson, K., Jorstad, S., Marscher, A., et al., (including Taylor, B.), 2016, Galax, 4, 64, Correlation Analysis of Delays between Variations of Gamma-Ray and Optical Light Curves of Blazars
    We have been performing multi-wavelength monitoring of a sample of -ray blazars since the launch of the Fermi Gamma-ray Space Telescope in 2008. We present -ray and optical light curves for several quasars and BL Lac objects from the sample to illustrate different patterns of variability. We investigate correlations between -ray and R-band light curves and, if these are statistically significant, determine delays between variations at the two wavebands. Such time delays can reveal the relative locations of the emitting regions in AGN jets and the origin of the high-energy photons. We present preliminary results of this analysis. Of the 29 blazars with sufficient time coverage, 17 display a significant, singular, correlated time lag when tested over the entire 7-year period. Of these sources, the six that exhibit a consistent time lag across a majority of epochs of high activity have lags of 0 7 days; the 11 without consistency across epochs of high activity generally display longer mean lags, with -ray leading optical. Eleven sources display no significant singular correlation over either the entire 7-year period or across shorter intervals. No significant difference is apparent between the BL Lac objects and FSRQs. Even after 7 years of monitoring, our correlation analysis remains plagued with uncertainties due to insufficient data.
  15. Hutter, D., Zavala, R., Tycner, C., et al., (including Sanborn, J., Franz, O.), 2016, ApJS, 227, 4, Surveying the Bright Stars by Optical Interferometry. I. A Search for Multiplicity among Stars of Spectral Types F-K
    We present the first results from an ongoing survey for multiplicity among the bright stars using the Navy Precision Optical Interferometer (NPOI). We first present a summary of NPOI observations of known multiple systems, including the first detection of the companion of Scuti with precise relative astrometry, to illustrate the instruments detection sensitivity for binaries at magnitude differences m 3 over the range of angular separation 3-860 milliarcseconds (mas). A limiting m700 3.5 is likely for binaries where the component spectral types differ by less than two. Model fits to these data show good agreement with published orbits, and we additionally present a new orbit solution for one of these stars, Her. We then discuss early results of the survey of bright stars at slant -20. This survey, which complements previous surveys of the bright stars using speckle interferometry, initially emphasizes bright stars of spectral types F0 through K2. We report observations of 41 stars of apparent visual magnitude mV slant 4.30, all having been observed on multiple nights. Analysis of these data produces fitted angular separations, position angles, and component magnitude differences for six previously known visual binaries. Three additional systems were examined as possible binaries, but no conclusive detection could be made. No evidence of close stellar companions within our detection limit of m 3 was found for the remaining 32 stars observed; however, uniform-disk angular diameters are reported for 11 of the resolved stars in this last group.
  16. Cibulkova, H., Durech, J., Vokrouhlicky, D., et al., (including Oszkiewicz, D.), 2016, A&A, 596, A57, Distribution of spin-axes longitudes and shape elongations of main-belt asteroids
    Context. Large all-sky surveys provide us with a lot of photometric data that are sparse in time (typically a few measurements per night) and can be potentially used for the determination of shapes and rotational states of asteroids. The method generally used to derive these parameters is the light curve inversion. However, for most asteroids their sparse data are not accurate enough to derive a unique model and the light curve inversion method is thus not very efficient.
    Aims: To fully utilize photometry sparse in time, we developed a new simplified model and applied it on the data from the Lowell photometric database. Our aim was to derive spin axis orientations and shape elongations of asteroids and to find out if there are some differences in distributions of these parameters for selected subpopulations.
    Methods: We modeled asteroids as geometrically scattering triaxial ellipsoids. Observed values of mean brightness and the dispersion of brightness were compared with computed values obtained from the parameters of the model, I.e., the ecliptical longitude and latitude of the pole and the ratios a/b, b/c of axes of the ellipsoid. These parameters were optimized to get the best agreement with the observation.
    Results: We found that the distribution of for main-belt asteroids is not uniform and is dependent on the inclination of the orbit. Surprisingly, the nonuniformity of distribution is larger for asteroids residing on low-inclination orbits. We also studied distributions of a/b for several groups of asteroids and found that small asteroids (D< 25 km) are on average more elongated than large ones.
  17. Grundy, W., Cruikshank, D., Gladstone, G., et al., (including Gladstone, G.), 2016, Natur, 539, 65, The formation of Charon's red poles from seasonally cold-trapped volatiles
    A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.
  18. Maier, E., Chien, L., Hunter, D., 2016, AJ, 152, 134, Turbulence and Star Formation in a Sample of Spiral Galaxies
    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. on the Small Magellanic Cloud, we use the third and fourth statistical moments, as indicators of structures caused by turbulence, to examine the neutral hydrogen (H I) column density of a sample of spiral galaxies selected from The H I Nearby Galaxy Survey. We apply the statistical moments in three different methodsthe galaxy as a whole, divided into a function of radii and then into grids. We create individual grid maps of kurtosis for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with their far-ultraviolet images taken by the Galaxy Evolution Explorer satellite.We find that the moments are largely uniform across the galaxies, in which the variation does not appear to trace any star-forming regions. This may, however, be due to the spatial resolution of our analysis, which could potentially limit the scale of turbulent motions that we are sensitive to greater than 700 pc. From comparison between the moments themselves, we find that the gas motions in our sampled galaxies are largely supersonic. This analysis also shows that the Burkhart et al. methods may be applied not just to dwarf galaxies but also to normal spiral galaxies.
  19. Benedict, G., Henry, T., Franz, O., et al., (including Wasserman, L.), 2016, AJ, 152, 141, The Solar Neighborhood. XXXVII: The Mass-Luminosity Relation for Main-sequence M Dwarfs
    We present a mass-luminosity relation (MLR) for red dwarfs spanning a range of masses from 0.62 {{ M }} to the end of the stellar main sequence at 0.08 {{ M }} . The relation is based on 47 stars for which dynamical masses have been determined, primarily using astrometric data from Fine Guidance Sensors (FGS) 3 and 1r, white-light interferometers on the Hubble Space Telescope (HST), and radial velocity data from McDonald Observatory. For our HST/FGS sample of 15 binaries, component mass errors range from 0.4% to 4.0% with a median error of 1.8%. With these and masses from other sources, we construct a V-band MLR for the lower main sequence with 47 stars and a K-band MLR with 45 stars with fit residuals half of those of the V band. We use GJ 831 AB as an example, obtaining an absolute trigonometric parallax, abs = 125.3 0.3 mas, with orbital elements yielding {{ M }}{{A}}=0.270+/- 0.004 {{ M }} and {{ M }}{{B}}=0.145+/- 0.002 {{ M }} . The mass precision rivals that derived for eclipsing binaries. A remaining major task is the interpretation of the intrinsic cosmic scatter in the observed MLR for low-mass stars in terms of physical effects. In the meantime, useful mass values can be estimated from the MLR for the ubiquitous red dwarfs that account for 75% of all stars, with applications ranging from the characterization of exoplanet host stars to the contribution of red dwarfs to the mass of the universe.

    Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555.

  20. Fulton, B., Howard, A., Weiss, L., et al., (including von Braun, K.), 2016, ApJ, 830, 46, Three Temperate Neptunes Orbiting Nearby Stars
    We present the discovery of three modestly irradiated, roughly Neptune-mass planets orbiting three nearby Solar-type stars. HD 42618 b has a minimum mass of 15.4 2.4 {M}\oplus , a semimajor axis of 0.55 au, an equilibrium temperature of 337 K, and is the first planet discovered to orbit the solar analogue host star, HD 42618. We also discover new planets orbiting the known exoplanet host stars HD 164922 and HD 143761 ( CrB). The new planet orbiting HD 164922 has a minimum mass of 12.9 1.6 {M}\oplus and orbits interior to the previously known Jovian mass planet orbiting at 2.1 au. HD 164922 c has a semimajor axis of 0.34 au and an equilibrium temperature of 418 K. HD 143761 c orbits with a semimajor axis of 0.44 au, has a minimum mass of 25 2 {M}\oplus , and is the warmest of the three new planets with an equilibrium temperature of 445 K. It orbits exterior to the previously known warm Jupiter in the system. A transit search using space-based CoRoT data and ground-based photometry from the Automated Photometric Telescopes (APTs) at Fairborn Observatory failed to detect any transits, but the precise, high-cadence APT photometry helped to disentangle planetary-reflex motion from stellar activity. These planets were discovered as part of an ongoing radial velocity survey of bright, nearby, chromospherically inactive stars using the Automated Planet Finder (APF) telescope at Lick Observatory. The high-cadence APF data combined with nearly two decades of radial velocity data from Keck Observatory and gives unprecedented sensitivity to both short-period low-mass, and long-period intermediate-mass planets.

    Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time was granted for this project by the University of HawaiI, the University of California, and NASA.

  21. Barros, S., Brown, D., Hebrard, G., et al., (including Llama, J., Skiff, B.), 2016, A&A, 593, A113, WASP-113b and WASP-114b, two inflated hot Jupiters with contrasting densities

    Aims: We present the discovery and characterisation of the exoplanets WASP-113b and WASP-114b by the WASP surveys, SOPHIE and CORALIE.
    Methods: The planetary nature of the systems was established by performing follow-up photometric and spectroscopic observations. The follow-up data were combined with the WASP-photometry and analysed with an MCMC code to obtain system parameters.
    Results: The host stars WASP-113 and WASP-114 are very similar. They are both early G-type stars with an effective temperature of ~5900 K, [Fe/H] ~ 0.12, and log g~ 4.1 dex. However, WASP-113 is older than WASP-114. Although the planetary companions have similar radii, WASP-114b is almost four times heavier than WASP-113b. WASP-113b has a mass of 0.48 MJup and an orbital period of ~4.5 days; WASP-114b has a mass of 1.77 MJup and an orbital period of ~1.5 days. Both planets have inflated radii, in particular WASP-113 with a radius anomaly of = 0.35. The high scale height of WASP-113b (~950 km) makes it a good target for follow-up atmospheric observations.
  22. Boro Saikia, S., Jeffers, S., Morin, J., et al., (including Hall, J.), 2016, A&A, 594, A29, A solar-like magnetic cycle on the mature K-dwarf 61 Cygni A (HD 201091)
    Context. The long-term monitoring of magnetic cycles in cool stars is a key diagnostic in understanding how dynamo generation and amplification of magnetic fields occur in stars similar in structure to the Sun.
    Aims: We investigated the temporal evolution of a possible magnetic cycle of 61 Cyg A. The magnetic cycle is determined from 61 Cyg A's large-scale field over its activity cycle using spectropolarimetric observations and compared to the solar large-scale magnetic field.
    Methods: We used the tomographic technique of Zeeman Doppler imaging (ZDI) to reconstruct the large-scale magnetic geometry of 61 Cyg A over multiple observational epochs spread over a time span of nine years. We investigated the time evolution of the different components of the large-scale field and compared it with the evolution of the star's chromospheric activity by measuring the flux in three different chromospheric indicators: Ca II H&K, H and Ca II infrared triplet lines. We also compared our results with the star's coronal activity using XMM-Newton observations.
    Results: The large-scale magnetic geometry of 61 Cyg A exhibits polarity reversals in both poloidal and toroidal field components, in phase with its chromospheric activity cycle. We also detect weak solar-like differential rotation with a shear level similar to that of the Sun. During our observational time span of nine years, 61 Cyg A exhibits solar- like variations in its large-scale field geometry as it evolves from minimum activity to maximum activity and vice versa. During its activity minimum in epoch 2007.59, ZDI reconstructs a simple dipolar geometry which becomes more complex when it approaches activity maximum in epoch 2010.55. The radial field flips polarity and reverts back to a simple geometry in epoch 2013.61. The field is strongly dipolar and the evolution of the dipole component of the field is reminiscent of solar behaviour. The polarity reversal of the large-scale field indicates a magnetic cycle that is in phase with the chromospheric and coronal cycle.
  23. Johns-Krull, C., Prato, L., McLane, J., et al., 2016, ApJ, 830, 15, H Variability in PTFO8-8695 and the Possible Direct Detection of Emission from a 2 Million Year Old Evaporating Hot Jupiter
    We use high time cadence, high spectral resolution optical observations to detect excess H emission from the 2-3 Myr old weak-lined T Tauri star PTFO 8-8695. This excess emission appears to move in velocity as expected if it were produced by the suspected planetary companion to this young star. The excess emission is not always present, but when it is, the predicted velocity motion is often observed. We have considered the possibility that the observed excess emission is produced by stellar activity (flares), accretion from a disk, or a planetary companion; we find the planetary companion to be the most likely explanation. If this is the case, the strength of the H line indicates that the emission comes from an extended volume around the planet, likely fed by mass loss from the planet which is expected to be overflowing its Roche lobe.
  24. Stern, S., Weaver, H., Olkin, C., et al., (including Grundy, W.), 2016, DPS, 48, 103.01, New Horizons: Overview of Results From and Plans After the Exploration of The Pluto System
    Essentially all of the data from the New Horizons Pluto system flyby that culminated in July 2015 is expected to be on Earth by the time of this meeting. As of mid-June 2016, about 75% of those data have been received. All near encounter observations downlinked so far have been examined and were determined to be successful; engineering data from the remaining observations yet to be downlinked indicates they were all successful as well. The first Planetary Data System (PDS) Pluto system delivery has been made; a second PDS delivery is planned for October, with still more deliveries leading to complete and final dataset archiving by late 2017. Numerous scientific results have been obtained, and over 40 scientific papers have been published or submitted by mid-June 2016. This invited review will examine the most interesting geological, compositional, atmospheric, and plasma results obtained about Pluto, Charon and their small moons, and will go on to explore the implications of key results for understanding dwarf planets in general and the origin of the Pluto system in specific. New Horizons is healthy and operating nominally. If its Kuiper Belt Extended Mission is approved, numerous KBO and heliospheric observations are planned for 2016 and beyond, including the very close flyby of the cold, classical KBO 2014 MU69 on 1 January 2019. We summarize these and other plans for New Horizons.
  25. Parker, A., Buie, M., Grundy, W., et al., 2016, DPS, 48, 106.08, Taking The Measure of Makemake's Moon
    We present the discovery and characterization of S/2015 (136472) 1, a satellite of the dwarf planet Makemake. The satellite was discovered in Hubble Space Telescope (HST) imagery collected in spring of 2015, found at a separation of 0.57" and ~1,300 times fainter than Makemake at the discovery epoch. The system was imaged in two visits separated by two days, and the satellite was visible in the first visit but undetectable in the second. Previous HST satellite searches also did not reveal S/2015 (136472) 1. Current observations constrain the satellite's orbit to be near an edge-on configuration, placing the system near a mutual event season. Follow-up observations will permit the measurement of Makemake's mass and density, as well as identify whether there is an upcoming mutual event season. We will discuss the current state of characterization of the system and its implications for Makemake's bulk, thermal, and surface properties, spin state, and the origin of S/2015 (136472) 1. Finally, we will address the current state of understanding regarding the population of dwarf planet satellites.
  26. Dias-Oliveira, A., Sicardy, B., Ortiz, J., et al., (including Thirouin, A.), 2016, DPS, 48, 106.09, 2003 AZ84: Size, shape, albedo and first detection of topographic features
    We analyze two multi-chord stellar occultations by the Trans-Neptunian Object (TNO) 2003 AZ84 observed on February 3, 2012 and November 15, 2014.They provide different elliptical limb fits that are consistent to within their respective error bars, but could also suggest a possible precession of the object (assumed here to be a Maclaurin spheroid). The derived equatorial radius and oblateness are Re = 393 7 km and = 0.057 in 2014 and Re = 414 13 km and = 0.165 in 2012, respectively. Those results are consistent with single-chord events observed in January 2011 and December 2013. The figures above provide geometric visual albedos of pV(2014) = 0.112 0.008 and pV(2012) = 0.114 0.020. Using the Maclaurin assumption, combined with possible rotational periods of 6.67 h and 10.56 h, we estimate density upper limits of 1.89 0.16g/cm3 and 0.77 0.07g/cm3 for the two dates, respectively.The 2014 event provides (for the first time during a TNO occultation) a grazing chord with a gradual disappearance of the star behind 2003AZ84's limb that lasts for more than 10 seconds. We rule out the possibility of a localized dust concentration as it would imply very high optical depth for that cloud. We favor a local topographic feature (chasm) with minimum width and depth of 22 2.5 km and 7 2.0 km, respectively. Features with similar depths are in fact observed on Pluto's main satellite, Charon, which has a radius of about 605 km, comparable to that of 2003AZ84.
  27. Schwamb, M., Fraser, W., Bannister, M., et al., (including Thirouin, A.), 2016, DPS, 48, 113.01, Surface Color Frequencies and Ratios Within the Kuiper Belt
    We have an understanding of the surface properties for the largest Kuiper belt objects (KBOs) which retain their primordial inventory of volatile ices. The vast majority of the known dwarf-planet sized bodies are bright enough to be studied through optical and infrared spectroscopy. For the typically smaller > 22 mag KBO, we must rely instead on what colors reveal by proxy; yet this picture remains incomplete. Most KBO physical property studies examine the hodgepodge set of objects discovered by various surveys with different and varying detection biases that make it difficult if not impossible to accurately estimate the sizes of the different surface color groups residing in the modern-day Kupier belt. The Colours of the Outer Solar System Origins Survey (Col-OSSOS) probes the surface properties within the Kuiper belt primarily through near simultaneous g,r and J colors with the Gemini North Telescope. The survey targets KBOs brighter than 23.6 r mag found by the Outer Solar System Origins Survey (OSSOS). With Col-OSSOS, we have a sample of KBO colors measured for a set of objects detected in a brightness limited survey, with a well-measured detection efficiency. This affords the first opportunity to explore the true frequency of surface colors within the Kuiper belt, subdivided by dynamical classification.Using the ~30 KBOs studied from the first complete OSSOS block, we present the observed and debiased ratio of neutral to red KBOs. We also measure the populations of the three color KBO subgroups (the red and neutral dynamically excited population and the red cold classical belt). Additionally, Kuiper belt formation models predict that the dynamically excited KBOs (hot classical belt, resonant orbits, and scattered disk) were implanted during Neptune's migration. With the true frequency of neutral to red bodies from Col-OSSOS, we examine the implications for the radial color distribution in the primordial planetesimal disk from which the excited KBOs originated.
  28. Rabinowitz, D., Benecchi, S., Grundy, W., et al., (including Thirouin, A.), 2016, DPS, 48, 120.10, Observations of Mutual Eclipses by the Binary Kuiper Belt Object Manwe-Thorondor
    The binary Kuiper Belt Object (385446) Manwe-Thorondor (aka 2003 QW111) is currently undergoing mutual events whereby the two ~100-km bodies alternately eclipse and occult each other as seen from Earth [1]. Such events are extremely rare among KBOs (Pluto-Charon and Sila-Nunam being notable exceptions). For Manwe-Thorondor, the events occur over ~0.5-d periods 4 to 5 times per year until the end of 2019. Here we report the results of observations to be made with the Soar 4m telescope at Cerro Pachon, Chile on 2016 Aug 25 and 26 UT, covering one of the deepest predicted eclipses. We use these observations to constrain the rotational variability of the two bodies, determine their physical properties (size, shape, albedo, density), and set limits on the presence of any prominent surface features.[1] Grundy, W. et al. 2012, Icarus, 220, 74
  29. Holler, B., Young, L., Bus, S., et al., (including Grundy, W.), 2016, DPS, 48, 120.17, Exploratory spectra of intermediate-sized KBOs with IRTF/SpeX+MORIS
    We observed 4 Kuiper Belt Objects (KBOs) for 2-3 half-nights each with the SpeX instrument on NASA's 3-meter IRTF. The 4 KBOs were 2007 OR10 (third largest KBO, possible presence of volatile ices), Salacia (potential Haumea family member but no previously detected water ice absorption), 2003 AZ84 (large enough to expect differentiation and water ice absorption, but none previously detected), and 2004 NT33 (only previous spectrum was inconclusive). Guiding on these faint targets (V magnitudes between 20.4 and 21.5) was made possible with the MORIS visible guide camera. Raw spectra were reduced with the spextool program (Cushing et al., 2004, PASP 116, 362-376). Combining all the spectra for a single object resulted in an average spectrum with an SNR that reached or exceeded 20 at a resolution of about 100; these are the highest-SNR near-infrared spectra ever obtained of these 4 objects. Analysis is currently underway to search for broad absorption features due to CH4, H2O (crystalline and amorphous), and CH3OH (methanol). Water ice models will also be fit to each average spectrum to quantify water ice fraction and spectral slope.
  30. Penteado, P., Trilling, D., Grundy, W., 2016, DPS, 48, 120.20, HST observations of faint Cold Classical KBOs
    The size distribution of the known Kuiper Belt Objects has been described by a double power law, with a break at R magnitude 25. There are two leading interpretations to this break: 1) It is the result of the collisional evolution, with the objects smaller than the break being the population most affected by collisional erosion. 2) The size distribution break is primordial, set during the Kuiper Belt formation.The low inclination KBOs, the Cold Classical population, is thought to have been dynamically isolated since the formation of the Solar System, and thus only collisions between Cold Classicals would have affected their size distribution. If the distribution is collisional, it probes parameters of the Kuiper Belt history: strengths of the bodies, impact energies and frequency, and the the number of objects. If the distribution is primordial, it reveals parameters of the Kuiper Belt accretion, as well as limits on its subsequent collisional history.We obtained HST observations of 16 faint Cold Classicals, which we combine with archival HST observations of 20 others, to examine the distribution of two properties of the smallest KBOs: colors and binary fraction. These properties can differentiate between a primordial and a collisional origin of the size distribution break. If the smaller bodies have been through extensive collisional evolution, they will have exposed materials from their interiors, which has not been exposed to weathering, and thus should be bluer than the old surfaces of the larger bodies. Another constraint can be derived from the fraction of binary objects: the angular momentum of the observed binaries is typically too high to result from collisions, thus a collisionally-evolved population would have a lower binary fraction, due to the easier separation of binaries, compared to the disruption of similar-sized bodies, and the easier disruption of the binary components, due to the smaller size.We present the constraints to the color and binary fraction distributions we obtained from observations probing probe the smallest observable KBOs.Support for programs 13031 and 13716 was provided by NASA through a grant from STScI.
  31. Arredondo, A., Bosh, A., Levine, S., 2016, DPS, 48, 120.21, A Tool for Optimizing Observation Planning for Faint Moving Objects
    Observations of small solar system bodies such as trans-Neptunian objects and Centaurs are vital for understanding the basic properties of these small members of our solar system. Because these objects are often very faint, large telescopes and long exposures may be necessary, which can result in crowded fields in which the target of interest may be blended with a field star. For accurate photometry and astrometry, observations must be planned to occur when the target is free of background stars; this restriction results in limited observing windows. We have created a tool that can be used to plan observations of faint moving objects. Features of the tool include estimates of best times to observe (when the object is not too near another object), a finder chart output, a list of possible astrometric and photometric reference stars, and an exposure time calculator. This work makes use of the USNOFS Image and Catalogue Archive operated by the United States Naval Observatory, Flagstaff Station (S.E. Levine and D.G. Monet 2000), the JPL Horizons online ephemeris service (Giorgini et al. 1996), the Minor Planet Center's MPChecker (http://cgi.minorplanetcenter.net/cgi-bin/checkmp.cgi), and source extraction software SExtractor (Bertin & Arnouts 1996). Support for this work was provided by NASA SSO grant NNX15AJ82G.
  32. Silva Martins-Filho, W., Griffith, C., Pearson, K., et al., (including Biddle, L.), 2016, DPS, 48, 122.24, Independet Component Analyses of Ground-based Exoplanetary Transits
    Most observations of exoplanetary atmospheres are conducted when a "Hot Jupiter" exoplanet transits in front of its host star. These Jovian-sized planets have small orbital periods, on the order of days, and therefore a short transit time, making them more ameanable to observations. Measurements of Hot Jupiter transits must achieve a 10-4 level of accuracy in the flux to determine the spectral modulations of the exoplanetary atmosphere. In order to accomplish this level of precision, we need to extract systematic errors, and, for ground-based measurements, the effects of Earth's atmosphere, from the signal due to the exoplanet, which is several orders of magnitudes smaller. Currently, the effects of the terrestrial atmosphere and the some of the time-dependent systematic errors are treated by dividing the host star by a reference star at each wavelength and time step of the transit. More recently, Independent Component Analyses (ICA) have been used to remove systematic effects from the raw data of space-based observations (Waldmann 2014,2012; Morello et al.,2015,2016). ICA is a statistical method born from the ideas of the blind-source separation studies, which can be used to de-trend several independent source signals of a data set (Hyvarinen and Oja, 2000). One strength of this method is that it requires no additional prior knowledge of the system. Here, we present a study of the application of ICA to ground-based transit observations of extrasolar planets, which are affected by Earth's atmosphere. We analyze photometric data of two extrasolar planets, WASP-1b and GJ3470b, recorded by the 61" Kuiper Telescope at Stewart Observatory using the Harris B and U filters. The presentation will compare the light curve depths and their dispersions as derived from the ICA analysis to those derived by analyses that ratio of the host star to nearby reference stars.References: Waldmann, I.P. 2012 ApJ, 747, 12, Waldamann, I. P. 2014 ApJ, 780, 23; Morello G. 2015 ApJ, 806; Morello et al. 2016 ApJ, 820, 86; Hyvarinen, A., and Oja, E. 2000 IEEE Transactions on Neural Networks, 13, 411.
  33. Osip, D., Rivkin, A., Pravec, P., et al., (including Moskovitz, N., Thirouin, A.), 2016, DPS, 48, 123.22, The Observing Working Group for the Asteroid Impact & Delfection Assessment (AIDA) Mission
    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint ESA-NASA mission concept currently under study. AIDA has two components: the Double Asteroid Redirect Test (DART) is the US component designed to demonstrate a kinetic impactor, while the Asteroid Impact Mission (AIM) spacecraft is on station to do a thorough pre- and post-impact survey of the Didymos system.Members of the DART and AIM Investigation teams have been organized into several joint and independent working groups. While there is overlap in subject matter and membership between the groups, we focus here on the activities of the Observing Working Group.The first work by the group was undertaken during the spring of 2015, before DART entered Phase A. During this period Didymos made an apparition reaching roughly V ~ 20.5 in brightness, and our top priority was constraining which of two very different pole positions for the Didymos system was correct. Several telescopes in the 2-4-m aperture range around the world attempted observations. An observed mutual event allowed the one pole position to be ruled out. Didymos is now thought to be a low-obliquity, retrograde rotator, similar to many other asteroid binary systems and consistent with expectations from a YORP-driven origin for the satellite.We have begun planning for the 2017 apparition, occurring in the first half of the year. Didymos will be ~20% brighter at opposition than the 2015 apparition. Scaling from the successful observations with the 4.3-m Lowell Discovery Channel Telescope indicates that we will need telescopes at least 4 m (or larger, for some of the tasks, or at times longer before or after the opposition) in primary diameter for the advanced characterization in 2017.Currently, we have four goals for this apparition: 1) confirming the preferred retrograde pole position; 2) gathering data to allow BYORP-driven changes in the mutual orbit to potentially be determined by later observations; 3) establishing whether or not the secondary is in synchronous rotation with the primary; and 4) constraining the inclination of the satellite orbit.
  34. Mommert, M., Moskovitz, N., Trilling, D., 2016, DPS, 48, 123.42, PHOTOMETRYPIPELINE - An Automated Pipeline for Calibrated Photometry
    Telescopes acquire massive amounts of imaging data every night. The goal of a large fraction of these observations is to obtain calibrated photometry for point sources - stars or moving Solar System targets - in different filters.We present PHOTOMETRYPIPELINE (PP, github.com/mommermi/photometrypipeline), an automated pipeline to obtain calibrated photometry from imaging data. PP is an open-source Python 2.7 software suite that provides image registration, aperture photometry, photometric calibration, and target identification with only minimal human interaction. For image registration, PP utilizes Source Extractor (Bertin & Arnouts 1996, A&AS, 117) and SWARP (Bertin et al. 2002, ASP Conf. S., 228) to find a plate solution for each frame, providing accurate target astrometry. Circular aperture photometry is performed using Source Extractor; an optimum aperture radius is identified using a curve-of-growth analysis. Photometric calibration is obtained through matching the background source catalog with star catalogs with reliable photometry (e.g., SDSS, URAT-1) in an iterative process; magnitude zeropoint accuracies are usually of the order of 0.03 mag, or better. Final calibrated photometry for each field source is written into a queriable database; target photometry is extracted from this database. Moving targets are identified using JPL Horizons (Giorgini et al. 1996, BAAS, 28) ephemerides. Image combination capabilities (using SWARP, Bertin 2006, ASP Conf. S., 112) are also available to improve the target's signal.PP is well-suited for data covering a few square arcminutes of the sky due to its dependence on background sources for registration and calibration. PP can be run on Unix-based systems on a simple desktop machine and is capable of realtime data analysis. PP has been developed for observations of moving targets, but can also be used on other observations. Efforts to improve the sky coverage for phometric calibration are in progress. Also, a module will be added to identify and extract data on serendipitously observed asteroids. PP was developed in the framework of the "Mission Accessible Near-Earth Object Survey" (MANOS) and is supported by NASA SSO grants NNX15AE90G and NNX14AN82G.
  35. Sarid, G., Stewart, S., Grundy, W., 2016, DPS, 48, 200.08, Let's Dense - Modifying densities and compositions through collisions of Kuiper belt objects
    Ice-rock bodies in the outer solar system preserve crucial information on past dynamical and physical conditions, through compositions and structure. Known dwarf planets have a large range of ice/rock ratios and maintain diverse satellite counterparts. Specific modification processes have not yet been demonstrated numerically and identification of intermediate evolution stages is lacking in simulations and observations.Barr & Schwamb (2016) hypothesized on how to interpret densities in the Kuiper belt according to different collision conditions, pointing to a two-mode process. We show how to reconstruct their distribution of primary density and satellite-to-total mass ratio, as a function of varying collision regimes, in similar and marginally-similar-sized collisions (dependent on target/impactor mass ratio). We varied the initial mass ratios, impact velocities and angles and differentiation state of large and mid-sized (300-1200 km in radius) colliding objects, in SPH-based shock physics simulations (using GADGET2 with EOS implementation). Fully, partial and non-differentiated initial configurations of each object are derived from a consistent calculation of thermal evolution histories and a pre-selected range in initial compositions and material properties.We will discuss the scaling of these simulations, as it informs our predictions for the survival and current presence of water and other volatile ice species. Intermediate-size KBOs (radii ~300-500 km) should be most amenable for buried ices to be resurfaced by impacts. A preliminary scaling relation between collision conditions and global shock processed state of the ice (H2O) and rock (silicate, serpentine) components will be discussed as well. We also predict the satellite-to-total mass ratio and primary density of objects that have not yet been observed to maintain a stable satellite system. These would be observations of massive satellites around ice-rich bodies. The predicted collision regime, between disruption and partial merging, is erosive Hit-and-Run, characterized by large ejected mass, but small velocities relative to the mutual escape velocity of the system.
  36. Spencer, J., Stern, S., Moore, J., et al., (including Grundy, W.), 2016, DPS, 48, 205.01, Geology and Composition of Pluto and Charon from New Horizons
    Data gathered by New Horizons during its July 2015 flyby has revolutionized our understanding of the geology and surface composition of Pluto and Charon. While much of Pluto's ice shell is ancient and rigid, as evinced by locally high crater densities and deep graben, much of the surface has been reworked, up to the present day, by a bewildering variety of geological processes. These include deposition and erosion of kilometers of mantle material, sublimation, apparent cryovolcanism, chaotic breakup of the crust to form rugged mountains, erosion and creation of channel networks by probable glacial action, and active glaciation. Pluto's anti-Charon hemisphere is dominated by 1000 km wide field of actively convecting nitrogen and other ices, informally called Sputnik Planum, occupying a large depression of probable impact origin. Color and composition is very varied, and is dominated by dark red tholins and N2, CH4, and CO ices, with H2O ice bedrock also exposed in many places. Apart from Sputnik Planum, color and composition is strongly correlated with latitude, showing the importance of insolation in controlling ice distribution. Charon shows pervasive extensional tectonism and locally extensive cryovolcanic resurfacing, both dating from early in solar system history. Its color and surface composition, dominated by H2O ice plus NH3 hydrate, is remarkably uniform apart from a thin deposit of dark red material near the north pole which may be due to cold-trapping and radiolysis of hydrocarbons escaping from Pluto. Neither Pluto nor Charon is likely to have experienced tidal heating during the period when observable landforms were created. Charon's surface shows resurfacing comparable in extent and age to many Saturnian and Uranian satellites such as Dione or Ariel, suggesting that observed activity on these satellites may not necessarily be tidally-driven. Pluto demonstrates that resurfacing on small volatile-rich icy bodies can be powered for at least 4.5 Ga by ongoing radiogenic and residual early heat alone, though the fact that Triton shows much more pervasive resurfacing than Pluto provides some evidence that Triton, unlike Pluto, has access to an additional heat source, presumably tidal.
  37. Young, L., Gladstone, R., Summers, M., et al., (including Grundy, W.), 2016, DPS, 48, 205.02, New Horizons: Gas and Plasma in the Pluto System
    NASA's New Horizons mission gave us information about gas and plasma in the Pluto system from Pluto's surface up to a distance of ~200,000 km beyond Pluto. This review will give an overview of our current theories and observations of the near-surface atmospheric structure; the properties, production and settling of Pluto's ubiquitous haze; the minor atmospheric species and atmospheric chemistry; the energetics and high-altitude thermal structure; the escape rate and the pickup of methane ions; the effect of methane impacting Charon; and Pluto's heavy-ion tail. Details are given in other presentations at this conference.This work was supported by NASA's New Horizons project.
  38. Cook, J., Cruikshank, D., Dalle Ore, C., et al., (including Grundy, W.), 2016, DPS, 48, 205.03, Spectroscopy of Pluto's Small Satellites
    On July 14, 2015, New Horizons made its closest approach to the Pluto system. Among its many tasks were spectroscopic observations of Nix, Hydra and Kerberos using LEISA (Linear Etalon Imaging Spectral Array), the near infrared imaging spectrograph, and component of the Ralph instrument (Reuter, D.C., Stern, S.A., Scherrer, J., et al. 2008, Space Sci. Rev. 140, 129). Shapes and composition inferred from images were discussed in Weaver et al. (2016, Science, 351). Styx was not observed with LEISA because it was too distant and faint.Observations of Nix were made at 60,000 and 162,000 km from New Horizons. At best, Nix filled 130 LEISA pixels. At the continuum level, the disk integrated spectrum has an I/F0.4 and a blue slope. Evident in the spectrum are deep bands at 1.5, 1.65 and 2.0 m, indicating crystalline H2O-ice. At band minimum, the I/F0.1 and 0.05 for the 1.5 and 2.0 m bands, respectively. These nearly saturated bands suggest that H2O-ice is either large grained or very pure. We also see an absorption band at 2.21 m that well matches NH3-hydrate.Observations of Hydra were made at 240,000 and 370,000 km from New Horizons. Hydra was barely resolved and covered 3-5 LEISA pixels. Hydra's spectrum has a continuum I/F0.35, a blue slope weaker than Nix's, crystalline H2O-ice and the 1.5 and 2.0 m bands have minimum I/F0.12 and 0.07, respectively. Since the bands on Hydra are slightly weaker, the H2O-ice grains are either smaller or contaminated by a greater fraction of dark material. Hydra's spectrum also shows the NH3-hydrate absorption at 2.21 m, but like the H2O-ice bands, it too appears weaker on Hydra than Nix.Finally, New Horizons made a LEISA observation of Kerberos at 394,000 km distance. At a scale of 24 km/pix, Kerberos fills 40% of a LEISA pixel. The signal-to-noise of the data is low. Nonetheless, we attempt to extract the spectrum.At DPS, we will present spectra of all three objects, examine the disk resolved spectra of Nix, present Hapke models and discuss why the H2O and NH3-hydrate bands appear deeper on Nix and Hydra than on Charon.This work was supported by NASA's New Horizons project.
  39. McKinnon, W., Moore, J., Spencer, J., et al., (including Grundy, W.), 2016, DPS, 48, 205.04, Sputnik Planum, Pluto: Composition, Geology, and Origin
    Large-grained nitrogen ice dominates Sputnik Planum (SP, all names herein being informal), both spectroscopically and rheologically, but spectroscopic evidence also exists for a considerable volume fraction of methane ice (Protopapa et al., Icarus, submitted). If true, this considerably broadens the range of possible viscosity contrasts controlling cellular convection within SP (see McKinnon et al., Nature 2016), while potentially complicating buoyancy arguments regarding the numerous "icebergs," especially for those at the western margin where the Hillary and Norgay Montes sources must be predominantly water-ice owing to their great topographic heights (Moore et al., Science 2016). Bergs carried into SP by glacial flow from the Tombaugh Regio uplands to the east must themselves also be erodible at the downwelling margins of convection cells, for otherwise the entire planum surface would become choked, Sargasso-like, over geologic time. Within SP, the cellular pattern loses its distinctive trough-bounded topographic signature towards the northwest, which is apparently not simply a solar incidence angle effect; this transition coincides with a lower surface N2 and greater CH4 abundance. Towards the south, the cellular pattern ceases, presumably due to a shallowing of the nitrogen-rich layer (which decreases the Rayleigh number, or convective drive), and which is consistent with the water-ice basement topography expected from an oblique, basin-forming impact on a sphere. The "stability" of the southern SP surface apparently promotes development of pits by sublimation, but both relict cell boundaries and pit ensembles show evidence of shear flow to the south. Upwelling centers within cells also show photometric evidence for elongation to the south, meaning these cells are not simply plumes, but longitudinal convective rolls. Simple scaling arguments suggest surface velocities on the order of 1 cm/yr to the south. This suggests a surface age for southern SP in excess of 10 Myr, but likely consistent with an impactor population deficient in smaller crater-forming bodies (see talk by Singer et al., this meeting).
  40. Noll, K., Levison, H., Buie, M., et al., (including Grundy, W.), 2016, DPS, 48, 208.05, HST Observations of a Large-Amplitude, Long-Period Trojan: (11351) Leucus
    (11351) Leucus (1997 TS25) is a Trojan that is notable for having one of the longest known rotation periods of any small body, T=514 h. A possible cause for this long period would be the existence of a tidally locked binary similar to the already-known long period binary Trojan, (617) Patroclus. If this were the case, the system would become tidally circularized in a time short compared to the age of the solar system. In such a case, the components would be separated by ~0.18 arcsec at lightcurve maximum, resolvable by WFC3. We carried out observations in June 2016, coordinated with groundbased observations to schedule near a maximum to test whether (11351) Leucus is binary. We describe the results of these observations.Observations of (11351) Leucus are of particular interest because it is a target of the Lucy mission, a Discovery mission currently in phase A and one of five that may be selected in early 2017. Searches for binary Trojans also offer multiple scientific benefits independent of mission status. Orbit-derived mass and density can be used to constrain planetary migration models. Low density is characteristic of bodies found in the dynamically cold Kuiper Belt, a remnant of the solar system's protoplanetary disk. Only one undisputed density has been measured in the Trojans, that of the binary (617) Patroclus, which has a low density of 0.8 g/cm3, similar to the low densities found in the Kuiper Belt. Slow rotators offer a set of targets that are tidally evolved systems and therefore are among the most attractive potential targets for an HST search.
  41. Zellem, R., Swain, M., Shkolnik, E., et al., (including Llama, J.), 2016, DPS, 48, 212.10, Stellar Variability Effects on Transit Spectroscopy
    Stellar variability caused by surface magnetic activity poses a great challenge to accurately and precisely characterize the atmospheres of transiting exoplanets. We present a preliminary analysis of the effects of unocculted star spots at IR wavelengths on planetary transmission and emission spectra. We will explore how stellar variability changes the derived exoplanet atmospheric parameters inferred through retrievals for a group of exoplanetary hosts stars. Our study includes stars ranging in activity levels from an inactive sun to a very active late-type star, and a range of planetary masses from super-Earths to Jupiters. These effects will be especially important for the high precision measurements (<100 ppm) needed to characterize the atmospheric composition of smaller planets. This work is critical for optimizing the exoplanet observing program of JWST, which will study known habitable zone transiting planets as well as new ones found by TESS orbiting nearby M dwarfs, which are more active than solar-type stars.
  42. Verbiscer, A., Buie, M., Binzel, R., et al., (including Grundy, W.), 2016, DPS, 48, 213.02, The Pluto System At Small Phase Angles
    Hubble Space Telescope observations of the Pluto system acquired during the New Horizons encounter epoch (HST Program 13667, M. Buie, PI) span the phase angle range from 0.06 to 1.7 degrees, enabling the measurement and characterization of the opposition effect for Pluto and its satellites at 0.58 microns using HST WFC3/UVIS with the F350LP filter, which has a broadband response and a pivot wavelength of 0.58 microns. At these small phase angles, differences in the opposition effect width and amplitude appear. The small satellites Nix and Hydra both exhibit a very narrow opposition surge, while the considerably larger moon Charon has a broader opposition surge. Microtextural surface properties derived from the shape and magnitude of the opposition surge of each surface contain a record of the collisional history of the system. We combine these small phase angle observations with those made at larger phase angles by the New Horizons Long Range Reconnaissance Imager (LORRI), which also has a broadband response with a pivot wavelength of 0.61 microns, to produce the most complete disk-integrated solar phase curves that we will have for decades to come. Modeling these disk-integrated phase curves generates sets of photometric parameters that will inform spectral modeling of the satellite surfaces as well as terrains on Pluto from spatially resolved New Horizons Ralph Linear Etalon Imaging Spectral Array (LEISA) data from 1.2 to 2.5 microns. Rotationally resolved phase curves of Pluto reveal opposition effects that only appear at phase angles less than 0.1 degree and have widths and amplitudes that are highly dependent on longitude and therefore on Pluto's diverse terrains. The high albedo region informally known as Sputnik Planum dominates the disk-integrated reflectance of Pluto on the New Horizons encounter hemisphere. These results lay the groundwork for observations at true opposition in 2018, when the Pluto system will be observable at phase angles so small that an Earth transit across the solar disk will be visible from Pluto and its satellites.
  43. Linscott, I., Protopapa, S., Hinson, D., et al., (including Grundy, W.), 2016, DPS, 48, 213.04, The structure and temperature of Pluto's Sputnik Planum using 4.2 cm radiometry
    New Horizons measured the radiometric brightness temperature of Pluto at 4.2 cm, during the encounter with two scans of the spacecraft's high gain antenna shortly after closest approach. The Pluto mid-section scan included the region informally known as Sputnik Planum, now understood to be filled with nitrogen ice. The mean radiometric brightness temperature at 4.2 cm, obtained in this region is 25 K, for both Right Circular Polarization (RCP) and Left Circular Polarization (LCP), well below the sublimation temperature for nitrogen ice. Sputnik Planum was near the limb and the termination of the radiometric scan. Consequently, the thermal emission was measured obliquely over a wide range of emission angles. This geometry affords detailed modeling of the angular dependence of the thermal radiation, incorporating surface and subsurface electromagnetic scattering models as well as emissivity models of the nitrogen ice. In addition, a bistatic radar measurement detected the scattering of a 4.2 cm uplink transmitted from Earth. The bistatic specular point was within Sputnik Planum and the measurements are useful for constraining the dielectric constant as well as the surface and subsurface scattering functions of the nitrogen ice. The combination of the thermal emission's angular dependence, RCP and LCP polarization dependence, and the bistatic scattering, yields estimates of the radiometric thermal emissivity, nitrogen ice temperature and spatial correlation scales.This work is supported by the NASA New Horizons Mission.
  44. Moore, J., Howard, A., Umurhan, O., et al., (including Grundy, W.), 2016, DPS, 48, 213.11, Bladed Terrain on Pluto: Possible Origins and Evolutions
    Pluto's Bladed Terrain (centered roughly 20N, 225E) covers the flanks and crests of the informally named Tartarus Dorsa with numerous roughly aligned blade-like ridges oriented ~North-South; it may also stretch considerably farther east onto the non-close approach hemisphere but that inference is tentative. Individual ridges are typically several hundred meters high, and are spaced 5 to 10 km crest to crest, separated by V-shaped valleys. Many ridges merge at acute angles to form Y-shape junctions in plan view. The principle composition of the blades themselves we suspect is methane or a methane-rich mixture. (Methane is spectroscopically strongly observed on the optical surfaces of blades.) Nitrogen ice is very probably too soft to support their topography. Cemented mixtures of volatile and non-volatile ices may also provide a degradable but relief supporting "bedrock" for the blades, perhaps analogous to Callisto. Currently we are considering several hypotheses for the origins of the deposit from which Bladed Terrain has evolved, including aeolian disposition, atmospheric condensation, updoming and exhumation, volcanic intrusions or extrusions, crystal growth, among others. We are reviewing several processes as candidate creators or sculptors of the blades. Perhaps they are primary depositional patterns such as dunes, or differential condensation patterns (like on Callisto), or fissure extrusions. Or alternatively perhaps they are the consequence of differential erosion (such as sublimation erosion widening and deepening along cracks), variations in substrate properties, mass wasting into the subsurface, or sculpted by a combination of directional winds and solar isolation orientation. We will consider the roles of the long-term increasing solar flux and short periods of warm thick atmospheres. Hypotheses will be ordered based on observational constrains and modeling to be presented at the conference.
  45. Singer, K., McKinnon, W., Greenstreet, S., et al., (including Grundy, W.), 2016, DPS, 48, 213.12, Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt Objects
    The impact craters observed during the New Horizons flyby of the Pluto system currently provide the most extensive empirical constraints on the size-frequency distribution of smaller impactors in the Kuiper belt. These craters also help us understand the surface ages and geologic evolution of the Pluto system bodies. Pluto's terrains display a diversity of crater retention ages and terrain types, indicating ongoing geologic activity and a variety of resurfacing styles including both exogenic and endogenic processes. Charon's informally named Vulcan Planum did experience early resurfacing, but crater densities suggest this is also a relatively ancient surface. We will present and compare the craters mapped across all of the relevant New Horizons LOng Range Reconnaissance Imager (LORRI) and Multispectral Visible Imaging Camera (MVIC) datasets of Pluto and Charon. We observe a paucity of small craters on all terrains (there is a break to a shallower slope for craters below 10 km in diameter), despite adequate resolution to observe them. This lack of small craters cannot be explained by geological resurfacing alone. In particular, the main area of Charon's Vulcan Planum displays no obviously embayed or breached crater rims, and may be the best representation of a production population since the emplacement of the plain. The craters on Pluto and Charon are more consistent with Kuiper belt and solar system evolution models producing fewer small objects.This work was supported by NASA's New Horizons project.
  46. Knight, M., Schleicher, D., 2016, DPS, 48, 217.02, Observations of comet 252P/LINEAR during its historically close approach to Earth in 2016 from Lowell Observatory
    We report on imaging and photometry of comet 252P/LINEAR acquired at Lowell Observatory during 2016 February-April. 252P passed 0.036 AU from Earth on March 21, among the closest passages on record. Its southern declination and the full moon made observations during the close encounter impractical from Lowell Observatory, but we observed 252P on one night each in February and early March, and on 13 nights from April 2-21 using the 4.3-m Discovery Channel Telescope, Hall 1.1-m, and 0.8-m. According to reports by other observers, the comet brightened significantly beginning in late-February and, coupled with the extreme close approach, was highly extended during our April observations. Narrowband photometry revealed a typical gas composition and an extremely low dust-to-gas ratio. The ratios remained essentially unchanged between late-February and April, e.g., during and after the extended "outburst" reported by other observers. 252P exhibited distinctly different coma morphology between dust and gas species. Enhanced images revealed a short sunward dust feature and the dust tail. Enhanced CN and C3 images exhibited a tilted spiral that was seen partially edge on approximately in the north-south directions. Enhanced OH images were also brightest along this direction but with considerably more material in the tailward hemisphere, potentially implying icy grains subject to radiation pressure. The CN coma morphology varied smoothly during a night and repeated every ~22 hr, implying a period of ~22 hr or a sub-multiple. There was also a repetition of features after ~95.5 hr, implying that the actual period is 7.35 +/- 0.05 hr. The repetition of features was most consistent April 2-7; the morphology diverged during later later nights, with the apparent spiral seen earlier separating into two or more distinct jet features. We will discuss these results as well as the results of our ongoing analyses. These studies were supported by NASA Planetary Astronomy grant NNX14AG81G.
  47. Bair, A., Schleicher, D., Knight, M., 2016, DPS, 48, 217.10, Results from Modeling CN Jets in Comet Lulin (C/2007 N3)
    We present results from Monte Carlo modeling of the CN jets on dynamically new Comet Lulin (C/2007 N3). Our model is based on 16 nights of narrowband imaging obtained with Lowell Observatory's 1.1-m Hall Telescope from 2009 January 30 through April 1, an interval during which our viewing orientation varied by more than 120 degrees. Following basic image enhancement by removing median radial profiles, two opposite pointing corkscrew jets were revealed, and a rotation period of 42 +/- 0.5 hr was determined (Knight & Schleicher 2009; IAU Circular #9025). The presence of these two distinct, non-overlapping jets, combined with the large change in aspect angle, made Lulin an excellent candidate for detailed 3-D jet modeling, allowing us to test a number of physical properties of outgassing which can eventually be utilized for other comets. We successfully reproduced Lulin's CN morphology using a nucleus having a tightly constrained obliquity of 95 deg with the axis pointing toward RA = 90 deg and Dec = +27 deg. The jet towards the west is centered at ~65 deg latitude and has a radius of ~25 deg, while the east jet is centered near -75 deg latitude and has a radius of ~15 deg. The longitudes differ by about 120 deg. The rotation axis crossed the plane of the sky on Feb 22, coincidently just prior to opposition. Our modeling shows that at this heliocentric distance of 1.4 AU, the CN gas continued to accelerate away from the nucleus out to a distance of about 20,000 km, reaching a velocity of 0.48 km/s. We also significantly improved the period determination since the model compensates for the rapidly changing viewing geometry, obtaining a sidereal period of 42.0 +/- 0.2 hr. We see a strong seasonal change in activity consistent with the variation in the sub-solar latitude from January until April as the CN jets change in brightness relative to each other. These and other results will be presented. Support is provided by NASA Planetary Atmospheres Grant NNX14AH32G.
  48. Bosh, A., Levine, S., Sickafoose, A., et al., 2016, DPS, 48, 224.01, Scattering and extinction: interpreting hazes in stellar occultation data
    There has been debate concerning interpretation of stellar occultation data and whether those data contain evidence for hazes within Pluto's atmosphere. Multiple layers of haze have been imaged in at Pluto with the New Horizons spacecraft; color-dependent differences in minimum flux from stellar occultations also suggests haze. We look at a purely geometric approach, to evaluate whether it is valid to sidestep details of atmospheric temperature structure and, in an approximate manner, conduct an analysis of the 2015 stellar occultation data that is consistent with the New Horizons imaging results. Support for this work was provided by NASA SSO grant NNX15AJ82G to Lowell Observatory.
  49. Person, M., Bosh, A., Sickafoose, A., et al., (including Dunham, E., Bida, T., Bright, L., Collins, P.), 2016, DPS, 48, 224.04, Implications of the Central Flash Analysis from the 2015 Pluto Stellar Occultation
    Two weeks before the historic New Horizons flyby of Pluto, a stellar occultation was observed from Australia and New Zealand (Bosh et al., 2016, Pasachoff et al., 2016, Sicardy et al., 2016). Prior to these observations, an extensive astrometric campaign (Bosh et al., this meeting) was conducted to carefully place the SOFIA aircraft within the central flash region of the occultation shadow. Multiple central flash chords were obtained and initial analysis indicated global asymmetry of Pluto's atmosphere (Person et al., 2015).Further analysis of these chords reveals asymmetries in Pluto's atmosphere stronger than those previously observed by either central flash measurements or occultation shadow fitting (Person et al., 2006, Olkin et al., 2014). Here we will discuss this revealed atmospheric asymmetry in terms of the bulk atmospheric movements necessary to cause distortions of this order, given the extreme surface sphericity seen by New Horizons (Nimmo et al., 2016), and its implications for surface ice transport scenarios (Hansen et al., 2015), and Pluto's seasonal evolution (Earle et al., 2015).
  50. Oszkiewicz, D., Grundy, W., Buie, M., et al., 2016, DPS, 48, 224.08, Spectroscopy of Pluto and Charon with HST during the encounter year
    Pluto is the largest of the handful of transneptunian bodies massive enough to retain, over the age of the solar system, an abundant inventory of volatiles including N2, CH4, and CO (Schaller et al. 2007). Sublimation and condensation act in concert with wind to efficiently transport heat (as well as the ices themselves) in response to diurnally and seasonally changing patterns of insolation (Spencer et al. 1997, Trafton et al. 1998). Recent indications suggest that observable changes could occur from one Earth year to the next (Grundy et al. 2014) and observations of Triton, with a similar inventory of volatile ices suggest that dramatic changes could occur on relatively short timescale (Hicks et al. 2000). The goal of this study is therefore to bridge the gap between sparse, multi-year spectral monitoring of Pluto and the brief, but extremely detailed snapshot provided by New Horizons spacecraft.We obtained high S/N spectra of Pluto and Charon separately with the HST's WFC3/IR grism G141. Altogether, we have collected data from ten visits at various sub-HST longitudes centered on the New Horizons encounter hemisphere. During each visit we obtained 8 dithered spectral images and 4 direct images in the F139M filter. The spectral reduction followed the recipe outlined in the WFC3 IR Grism Data Reduction Cookbook. The final spectra were combined to achieve spectral uncertainty at the level of around 0.2\% (that is five times betterthan in our previous studies). The combined spectra were then explored for sub-latitude, sub-longitude, and phase angle dependences.
  51. Thompson, G., Hanley, J., Grundy, W., et al., (including Roe, H.), 2016, DPS, 48, 224.10, A Low Temperature Eutectic Methane-Ethane Liquid: A Potential Geologic Fluid in the Outermost Solar System
    Many icy bodies and moons in the solar system contain methane and ethane, including Titan, Triton, Pluto, Eris, Makemake, and likely others. The material properties of these species and their interactions with one another are still inadequately characterized. To provide insight into the behaviors of these species we conducted a series of laboratory experiments to map the liquidus line as a function of temperature and composition. The interaction of ethane and methane yields a eutectic mixture and depresses the freezing point to ~72 K, almost 20 K colder than the normal freezing points of either pure species. The eutectic composition is 64% CH4 and 36% C2H6. This phenomenon may enable geological processes involving liquids in the near surface environments of bodies once thought too cold and/or that have surface pressures too low to support liquid phases. The addition of other cosmochemically abundant species may suppress freezing points even further (see Hanley et al., this conference).
  52. Farnham, T., Knight, M., Schleicher, D., 2016, DPS, 48, 301.01, The Rotation State of Comet 103P/Hartley 2
    On November 4, 2010, the Deep Impact (DI) spacecraft made its closest approach to comet 103P/Hartley 2, passing only 694 km from the nucleus. Observations of the coma produced a lightcurve that shows the nucleus is in a state of non-principal axis rotation that evolves with time, while other observations revealed a nucleus that has concentrated collimated jets driven by CO2 emission (A'Hearn et al., 2011), large variability in the production of H2O and CO2 (Besse et al. 2016), and ice patches on the surface (Sunshine et al. 2011). To properly interpret the significance of these phenomena, it is necessary to understand the rotation of the nucleus, so that its thermal history can be derived and properly modeled, while at the same time, it is likely that the comet's high activity levels play an important role in the nucleus dynamics.An analysis of the lightcurve by Belton et al (2013) described the comet's rotation state, with two periodicities (primary of 18 h, secondary of 28 or 55 h) that change with time. Although their solution describes the periodicities observed around closest approach, it is insufficient to reproduce the changes in coma morphology with time. We are performing an analysis of the structures in the coma (Farnham 2009), using Monte Carlo routines to model the outflowing dust produced by active sources on the nucleus, to derive a comprehensive solution for the nucleus' rotation.We are also obtaining new observations of Hartley 2 in June/July 2016 (r~3.2 AU) to measure the nucleus' primary component period before the comet becomes highly active. This will provide an end-state measure of the rotation from the 2010 apparition, as well as a starting value for the current apparition, to allow its continuing evolution to be monitored. We will present an update on the status and preliminary results of these analyses.This work is funded by NASA Grant NNX12AQ64G.A'Hearn, M.F., et al. (2011) Science 332, 1396-1400Belton M.J.S., et al. (2013) Icarus 222, 595-609.Besse, S., et al. (2016) This meeting.Farnham, T.L., (2009) Planetary and Space Science 57, 1192-1217.Sunshine, J.M., et al., (2011) EPSC-DPS Abs. 6, #1345.
  53. Schmitt, B., Philippe, S., Grundy, W., et al., 2016, DPS, 48, 306.05, Distribution, physical state and mixing of materials at the surface of Pluto from New Horizons
    In July 2015 the New Horizons spacecraft recorded a large set of data on Pluto, in particular with the LEISA spectro-imager dedicated to the study of the surface composition.In this talk we report a study of the distribution and physical state of the ices and non-ice materials on Pluto's surface and their mode and degree of mixing. Principal Component analysis as well as specific spectral indicators and correlation plots are used on high resolution LEISA spectro-images covering the whole illuminated face of Pluto. Qualitative distribution maps have been obtained for the 4 main condensed molecules, N2, CH4, CO, H2O as well as for the visible-dark red material. These maps indicate the presence of 3 different types of ices: N2-rich:CH4:CO ices, CH4-rich:(CO:N2?) ices and H2O ice. Their mixing lines and with the dark reddish material are studied. CH4 is mixed at the molecular level with N2 and CO, thus forming a ternary molecular mixture that follows its phase diagram with low solubility limits. The occurrence of a N2-rich - CH4-rich ices mixing line associated with a decrease of the CO/CH4 ratio tell us that a fractionation sublimation sequence transforms N2-rich ice into either a N2-rich - CH4-rich binary mixture at the surface or an upper CH4-rich(:CO:N2) ice crust that may hide the N2-rich ice below. The CH4-rich - H2O mixing line witnesses the subsequent sublimation of CH4 ice left behind by the N2:CO sublimation (N spring-summer), or a direct condensation of CH4 ice on cold H2O ice (S autumn). The very sharp spatial transitions between CH4-containing ices and the dark red material are probably due to thermal incompatibility. Finally there is some spatial mixing of the reddish material covering H2O ice. H2O ice appears to be the substratum on which other ices condense or non-volatile organic material is deposited from the atmosphere. The spatial distribution of these materials is very complex.The high spatial definition of all these composition maps will allow us to compare them with Pluto's geologic features observed by LORRI panchromatic and MVIC multispectral imagers to better understand the geophysical processes in action at the surface of this astonishingly active cold world.
  54. Protopapa, S., Grundy, W., Reuter, D., et al., 2016, DPS, 48, 306.06, Unveiling Pluto's global surface composition through modeling of New Horizons Ralph/LEISA data
    We present compositional maps of Pluto derived from data collected with the Linear Etalon Imaging Spectral Array (LEISA), part of the New Horizons Ralph instrument (Reuter et al., 2008). Previous analysis of band depths, equivalent widths, and principal components have permitted qualitative analysis of the physical state of Pluto's surface (Grundy et al. 2016; Schmitt et al. 2016); the maps presented here are fully quantitative, generated by applying a complete pixel-by-pixel Hapke radiative transfer model to the near infrared LEISA spectral cubes. These maps quantify the spatial distribution of both the absolute abundances and textural properties of the volatiles methane and nitrogen ices and non volatiles water ice and tholin. Substantial reservoirs of methane and nitrogen ices cover the substratum which, in the absence of volatiles, reveals the presence of water ice, as expected given Pluto's size and temperature. We identify large scale latitudinal variations of methane and nitrogen ices which can help setting constraints to volatile transport models. To the north, by about 55 deg latitude, the nitrogen abundance smoothly tapers off to an expansive polar plain of predominantly methane ice. This transition well correlates with expectations of vigorous spring sublimation after a long polar winter. Continuous illumination northward of 75 deg over the past twenty years, and northward of 55 deg over the past ten years, seems to have sublimated the most volatile nitrogen into the atmosphere, with the best chance for redeposition occurring at points southward. This loss of surface nitrogen appears to have created the polar bald spot seen in our maps and also predicted by Hansen and Paige (1996). Regions that stands out for composition with respect to the latitudinal pattern described above are also going to be discussed. An example is given by informally named Sputnik Planum, where the physical properties of methane and nitrogen are suggestive of the presence of a cold trap or possible volatile stratification.This work was supported by NASA's New Horizons project. S. Protopapa thanks the NASA grant #NNX16AC83G.
  55. Grundy, W., Binzel, R., Cook, J., et al., 2016, DPS, 48, 306.07, Pluto's Nonvolatile Chemical Compounds
    Despite the migration of Pluto's volatile ices (N2, CO, and CH4) around the surface on seasonal timescales, the planet's non-volatile materials are not completely hidden from view. They occur in a variety of provinces formed over a wide range of timescales, including rugged mountains and chasms, the floors of mid-latitude craters, and an equatorial belt of especially dark and reddish material typified by the informally named Cthulhu Regio. NASA's New Horizons probe observed several of these regions at spatial resolutions as fine as 3 km/pixel with its LEISA imaging spectrometer, covering wavelengths from 1.25 to 2.5 microns. Various compounds that are much lighter than the tholin-like macromolecules responsible for the reddish coloration, but that are not volatile at Pluto surface temperatures such as methanol (CH3OH) and ethane (C2H6) have characteristic absorption bands within LEISA's wavelength range. This presentation will describe their geographic distributions and attempt to constrain their origins. Possibilities include an inheritance from Pluto's primordial composition (the likely source of H2O ice seen on Pluto's surface) or ongoing production from volatile precursors through photochemistry in Pluto's atmosphere or through radiolysis on Pluto's surface. New laboratory data inform the analysis.This work was supported by NASA's New Horizons project.
  56. Olkin, C., Reuter, D., Stern, S., et al., (including Grundy, W.), 2016, DPS, 48, 306.08, The Color and Surface Composition of Mountains on Pluto
    The New Horizons mission revealed that there are mountains along the western edge of the large glacier that dominates Pluto's anti-Charon hemisphere. This talk will focus on the color and surface composition of the four large mountainous regions named Al Idrisi Montes, Bare Montes, Hillary Montes and Norgay Montes (all feature names are informal).The Al Idrisi Montes are large blocks up to 40 km across and 5 km high that appear to be broken off of the ice crust and transported into Sputnik Planum (Moore et al. 2016). The color of this region as a function of latitude will be presented as well as the color differences between the blocks and the interstitial material between the blocks. Moving south along the edge of Sputnik Planum, the next mountainous region is Bare Montes. Part of the Bare Montes resembles Al Idrisi Montes with its chaotic blocky structure, but there is a significant difference in color between these regions. The Bare Montes are more red than Al Idrisi Montes and this region's color more closely matches the nearby terrain of Cthulhu Regio. Continuing south, to the Hillary and Norgay Montes regions these topographic features become less red with both red and neutral colors on their slopes. The Hillary Montes show both red and neutral colors in the ices surrounding the peaks.This work will provide a quantitative comparison of the color and composition across these 4 mountainous regions using data from the Ralph instrument. Ralph has 4 color filters: blue (400-550 nm), red (540-700 nm), near IR (780-975) and methane filter (860-910 nm) and collects infrared imaging spectrometric data (from 1.25-2.5 microns).This work was supported by NASA's New Horizons project.
  57. Dalle Ore, C., Cook, J., Cruikshank, D., et al., (including Grundy, W.), 2016, DPS, 48, 306.09, Charon's, Hydra's, and Nix's near IR spectra as seen by New Horizons
    Charon, Pluto's largest satellite, is a predominantly grey-color icy world covered mostly in H2O ice, with spectral evidence for NH3 and/or its hydrates, as previously reported (Cook et al. 2007, ApJ. 663, 1406; Verbiscer et al. 2007, LPSC 38, 2318; Merlin et al. 2010, Icarus, 210, 930; Cook et al. 2014, AAS/DPS Abstracts, 46, #401.04; Holler et al. 2016, submitted, arXiv:1606.05695). In their 2010 work, Merlin et al. reported the presence of ammonia species along with H2O ice both in crystalline and amorphous phase. They introduced a blue component to model the slope present in their near-IR observations, which could not be otherwise reproduced without the adoption of an ad hoc component. The presence of ammonia and H2O in its crystalline form prompted Cook et al. (2007) to suggest cryovolcanism as a favored mechanism of resurfacing although the geological evidence for volcanism reported from New Horizons imaging observations does not appear to be recent (Moore et al. Science, 351, 1284).We analyze one of New Horizons' observations of Charon taken with the LEISA imaging spectrometer from a distance of ~82,000 km at high spatial resolution (4.9 km/pixel). Images from the New Horizons spacecraft reveal a surface with terrains of seemingly different ages and a moderate degree of localized coloration.Hydra was observed by New Horizons at a distance 240,000 and 370,000 hardly resolving its disk. Nix on the other hand was observed from a much more favorable distance of 60,000 and 162,000 km revealing a nearly uniform surface coloration and structure.Although Hydra could hardly be resolved at the flyby distance we have obtained its spectral signature and we compare it with those of Charon and Nix. A feature at ~2.2 m, corresponding to the NH3 and/or NH3 hydrates, is visible subtly on Charon and clearly on Hydra and Nix hinting at the possibility that NH3 might be less volatile than previously thought and making the need for recent cryovolcanism less crucial.Preliminary modeling indicates uniformity in amounts and grain sizes of most components, a homogeneity that seems to be the trademark of Charon's surface.This work was supported by NASA's New Horizons project.
  58. Schleicher, D., Bair, A., 2016, DPS, 48, 308.04, Chemical and Physical Properties of Comets in the Lowell Database: Results from Four Decades of Narrowband Photometry
    As remnants from the epoch of early solar system formation, comet nuclei are less processed than any other class of objects currently available for detailed study. Compositional and physical studies can therefore be used to investigate primordial conditions across the region of comet formation and/or subsequent evolutionary effects. With these goals, a long duration program of comet narrowband photometry was begun in 1976 and results for 85 comets were published by A'Hearn et al. (1995; Icarus 118, 223). Observations continued and we performed a new set of analyses of data obtained through mid-2011. Following a hiatus due to lack of funding and other competing priorities, we have now resumed our efforts at completing this project while also incorporating the most recent five years of data. The database now includes 191 comets obtained over 848 nights. A restricted subset of 116 objects were observed multiple times and are considered well-determined; these form the basis of our compositional studies. Using a variety of taxonomic techniques, we identified seven compositional classes for the data up to 2011 and anticipate no changes with the newest additions. Several classes are simply sub-groups of the original carbon-chain depleted class found by A'Hearn et al.; all evidence continues to indicate that carbon-chain depletion reflects the primordial composition at the time and location of cometary accretion and is not associated with evolution. Another new class contains five comets depleted in ammonia but not depleted in carbon-chain molecules; it is unclear if this group is primordial or not. In comparison, clear evidence for evolutionary effects are seen in the active fractions for comet nuclei -- decreasing with age -- and with the dust-to-gas ratio -- decreasing with age and perihelion distance, implying an evolution of the surface of the nucleus associated with the peak temperature attained and how often such temperatures have been reached. Updates of these and other results including data from the last five years will be presented. Support was provided by NASA Planetary Atmospheres grant NNX08AG19G.
  59. Fuentes, C., Trilling, D., Knight, M., et al., 2016, DPS, 48, 311.03, Constraining the Interior Earth Objects population
    Interior Earth Objects (IEOs) are among the least known populations in the Solar Sytem. Ground-based surveys are extremely inefficient in surveying them as most of the time IEOs are located inside the orbit of the Earth. We present observational constraints to the IEO population from STEREO (Solar TErrestrial RElations Observatory). This is the first result of searching through the archival STEREO data. Although after analyzing a year's worth of data we found no new IEOs, we observed hundreds of known asteroids. Our survey efficiency is computed with known and implanted synthetic objects, yielding a limiting magnitude of V~14.5. We constrain different IEO population models, yielding an upper limit for the total number of IEOs in line with previous estimates.
  60. Young, L., Stern, S., Olkin, C., et al., (including Grundy, W.), 2016, DPS, 48, 312.02, New Horizons at Pluto: Asking the right questions
    In the 1980's and 1990's, breakthroughs about Pluto and the outer solar system laid the groundwork for the Outer Planets Science Working Group (1992), the Pluto Kuiper Express mission Science Definition Team (1996), and the Announcement of Opportunity for the Pluto Kuiper-Belt mission in 2001. These included specific science goals that molded the mission design, instrument selection, and observing sequence. These goals held up amazingly well over the decades. This historical review of New Horizons will explain how ground-based and theoretical work prepared us for a successful investigation of Pluto, and speculate on some of the new questions raised by the New Horizons flyby of the Pluto system.This work was supported by NASA's New Horizons project.
  61. Bosh, A., Dunham, E., Zuluaga, C., et al., (including Levine, S.), 2016, DPS, 48, 312.03, Stellar Occultations from Airborne Platforms: 1988 to 2016
    Observing a stellar occultation by a solar system body with an airborne telescope requires precise positioning of the observer within the shadow cast onto the Earth. For small bodies like Pluto and Kuiper Belt objects, smaller than the Earth, the challenge is particularly intense, with the accuracy of the astrometric and flight planning determining whether the observation succeeds or fails. From our first airborne occultation by Pluto in 1988 aboard the Kuiper Airborne Observatory (KAO), to our most recent event by Pluto in 2015 aboard the Stratospheric Observatory for Infrared Astronomy (SOFIA), we have refined our astrometric and flight planning systems to the point where we can now place an airborne observer into the small central flash zone. We will discuss the history of airborne observation of occultations while detailing the improvements in the astrometric processes. Support for this work was provided by NASA SSO grant NNX15AJ82G to Lowell Observatory.
  62. Cibulkova, H., Durech, J., Vokrouhlicky, D., et al., (including Oszkiewicz, D.), 2016, DPS, 48, 326.07, Distribution of spin axes and shape elongations of main-belt asteroids
    Photometric data that are sparse in time (typically few measurements per night over ~15 years) are a potential source of information about shapes and rotational states of asteroids. However, currently available data are usually not accurate enough to derive a unique sidereal rotation period and corresponding shape model by the lightcurve inversion method. To fully utilize sparse-in-time data, we have developed a new simplified model that provides an approximate solution for the orientation of the spin axis (, ) and ratios of axes of the ellipsoid, a/b, b/c (asteroids are modelled as geometrically scattering triaxial ellipsoids). The observed values of mean brightness (over one apparition) and the dispersion of brightness are compared with values computed from the model parameters (, , a, b, setting c=1) which are optimized to get the best agreement. The model was applied on the data from Lowell photometric database. We found that the distribution of pole ecliptic longitude is nonuniform and that this nonuniformity is larger for asteroids with low inclination of their orbits. The second main result is that small asteroids (D<25 km) are on average more elongated (a/b ~ 1.6) than the large ones (for D>50 km the mean value of a/b is 1.3).
  63. Moskovitz, N., Oszkiewicz, D., Skiff, B., et al., 2016, DPS, 48, 327.05, Non-Vestoid candidates in the inner Main Belt
    Most Howardite-Eucrite-Diogenite (HED) meteorites (analogues to V-type asteroids) are thought to originate from asteroid (4) Vesta. However some HEDs show distinct oxygen isotope ratios and therefore are thought to originate from other asteroids. In this study we try to identify asteroids that may represent parent bodies of those mismatching HEDs. In particular the origin of the anomalous Bunburra Rockhole meteorite was traced back to the inner main asteroid belt, showing that there might be asteroids that are not genetically linked to the asteroid (4) Vesta (the main source of V-type asteroids and HED meteorites) in the inner main belt. In this work we identify V-type asteroids outside the dynamical Vesta family whose rotational properties (retrograde vs prograde rotation) suggest the direction of Yarkovsky drift that sets them apart from typical Vestoids and Vesta fugitives. Specificly Nesvorny et al. 2008 simulated escapes paths from the Vesta family and showed that typical Vesta fugitives in the inner main asteroid belt at semi-major axis a < 2.3 AU have to have retrograde rotations and physical and thermal parameters that maximize the Yarkovsky force in order to evolve to scattered orbits within 1-2 Gys (age of the Vesta collisional family). Therefore large asteroids outside the Vesta family and with a < 2.3 AU and having thermal and rotational properties minimizing the Yarkovsky drift or showing Yarkovsky drift direction towards (4) Vesta are the best candidates for non-Vestoidal V-type asteroids and therefore parent bodies of anomalous HED. In this study we have performed accurate photometric observations and determined sense of rotation for several asteroids testing their links to Vesta and anomalous HED. We have found several potential non-Vestoid candidates. Those objects have to be studied in more detail to fully confirm their link to anomalous HEDs.
  64. Navarro-Meza, S., Mommert, M., Reyes-Ruiz, M., et al., (including Moskovitz, N.), 2016, DPS, 48, 327.06, First results from the rapid-response spectrophotometric characterization of Near-Earth objects using RATIR
    We are carrying out a program to obtain rapid-response spectrophotometric characterization of newly discovered Near Earth Objects. Our first results, based on observations made with WFCAM on UKIRT, are presented in Mommert et al. (2016). Here we present a preliminary analysis of the r-i distribution of ~140 small (<500m) NEOs observed with the RATIR instrument on the 1.5-m telescope on San Pedro Martir. The observations are made in queue mode, and the data processing is carried out autonomously. Our goals are to derive coarse taxonomic and therefore compositional classifications for each of these objects, which will allow us to derive composition as a function of NEO size. This work is part of a collaboration in which we will characterize hundreds of NEOs that are generally too faint for other characterization techniques (down to V~21). This work is supported by funding from NASA's Solar System Observations program.
  65. Avner, L., Trilling, D., Dunham, E., 2016, DPS, 48, 327.11, Flagstaff Robotic Survey Telescope (FRoST): Rapid Response for NEOs
    The Flagstaff Robotic Survey Telescope (FRoST) is a robotic 0.6m Schmidt telescope that will be used for instant follow-up observations of newly discovered Near Earth Objects (NEOs). Here, we present the progress being made on FRoST as well as the remaining tasks until the telescope is fully operational. With more than one thousand NEOs being found yearly, more telescopes are needed to carry out follow-up observations. Most NEOs are found at their peak brightness, meaning that these observations need to happen quickly before they fade. By using the Catalina Sky Survey Queue Manager, FRoST will be able to accept interruptions during the night and prioritize observations automatically, allowing instant follow-up observations. FRoST will help refine the orbit of these newly discovered objects while providing optical colors. We will ingest information from the NEOCP and JPL's Scout program at five minute intervals and observe newly discovered targets robotically, process the data automatically, and autonomously generate astrometry and colors. We estimate that will we provide essentially 100% recovery of objects brighter than V~20. This work was supported by the NSF MRI program as well as by NAU and Lowell Observatory.
  66. Levine, S., Gosmeyer, C., 2016, DPS, 48, 331.03, Modeling the exchange of comets between the Sun and passing stars in a low stellar density environment
    We investigated the importance of close encounters between our Sun and its Oort cloud and passing stars with similar Oort clouds in the low stellar density environment of the outer portion of our Galaxy. By constructing a set of interaction cross-sections that describe the interchange of material between the two passing Oort clouds, and then randomly computing sets of encounters that a star would have during its orbit in the Galaxy over a period of time equivalent to the life of the Sun after the dissolution of its birth cluster, we have examined how the ensemble of passing encounters could impact the evolution of our Oort cloud. From the set of 1,000 possible realizations of the interactions over a solar lifetime, we find that the resulting solar Oort cloud is likely to be significantly eroded as a result of the set of encounters, and is also likely today to contain a significant amount of material that was formed in passing extra-solar systems.
  67. Thomas, C., Moskovitz, N., Hinkle, M., et al., (including Thirouin, A., Burt, B.), 2016, DPS, 48, 410.02, The Mission Accessible Near-Earth Objects Survey (MANOS): spectroscopy results
    The Mission Accessible Near-Earth Object Survey (MANOS) is an ongoing physical characterization survey to build a large, uniform catalog of physical properties including lightcurves and visible wavelength spectroscopy. We will use this catalog to investigate the global properties of the small NEO population and identify individual objects that can be targets of interest for future exploration. To accomplish our goals, MANOS uses a wide variety of telescopes (1-8m) in both the northern and southern hemispheres. We focus on targets that have been recently discovered and operate on a regular cadence of remote and queue observations to enable rapid characterization of small NEOs. Targets for MANOS are selected based on three criteria: mission accessibility, size, and observability. With our resources, we observe 5-10 newly discovered sub-km NEOs per month. MANOS has been operating for three years and we have observed over 500 near-Earth objects in that time.We will present results from the spectroscopy component of the MANOS program. Visible wavelength spectra are obtained using DeVeny on the Discovery Channel Telescope (DCT), Goodman on the Southern Astrophysical Research (SOAR) telescope, and GMOS on Gemini North and South. Over 300 NEO spectra have been obtained during our program. We will present preliminary results from our spectral sample. We will discuss the compositional diversity of the small NEO population and how the observed NEOs compare to the meteorite population.MANOS is funded by the NASA Near-Earth Object Observations program.
  68. Thirouin, A., Moskovitz, N., Binzel, R., et al., (including Burt, B.), 2016, DPS, 48, 411.02, The Mission Accessible Near-Earth Objects Survey (MANOS): photometric results
    The Mission Accessible Near-Earth Object Survey (MANOS) is a physical characterization survey of Near-Earth Objects (NEOs) to provide physical data for several hundred mission accessible NEOs across visible and near-infrared wavelengths. Using a variety of 1-m to 8-m class telescopes, we observe 5 to 10 newly discovered sub-km NEOs per month in order to derive their rotational properties and taxonomic class.Rotational data can provide useful information about physical properties, like shape, surface heterogeneity/homogeneity, density, internal structure, and internal cohesion. Here, we present results of the MANOS photometric survey for more than 200 NEOs. We report lightcurves from our first three years of observing and show objects with rotational periods from a couple of hours down to a few seconds. MANOS found the three fastest rotators known to date with rotational periods below 20s. A physical interpretation of these ultra-rapid rotators is that they are bound through a combination of cohesive and/or tensile strength rather than gravity. Therefore, these objects are important to understand the internal structure of NEOs. Rotational properties are used for statistical study to constrain overall properties of the NEO population. We also study rotational properties according to size, and dynamical class. Finally, we report a sample of NEOs that are fully characterized (lightcurve and visible spectra) as the most suitable candidates for a future robotic or human mission. Viable mission targets are objects with a rotational period >1h, and a delta-v lower than 12 km/s. Assuming the MANOS rate of object characterization, and the current NEO population estimates by Tricarico (2016), and by Harris and D'Abramo (2015), 10,000 to 1,000,000 NEOs with diameters between 10m and 1km are expected to be mission accessible. We acknowledge funding support from NASA NEOO grant number NNX14AN82G, and NOAO survey program.
  69. Becker, T., Retherford, K., Hanley, J., et al., 2016, DPS, 48, 429.10, Mid-IR Spectral Search for Salt SIgnatures on Europa
    We present mid-IR spectra of Europa's leading and trailing hemispheres obtained with the NASA IRTF/TEXES instrument on March 28 and March 30, 2015. The observations span from ~10 - 11 microns with a resolving power of R ~2500. Few observations of Europa have been made at these wavelengths, and the high spectral resolution of the instrument enables the identification of distinguishing spectral features in this relatively unexplored bandpass. While the leading hemisphere of Europa consists of relatively pure water ice, the trailing hemisphere's surface contains a mix of ice and some other component, causing the surface to appear reddish at visible wavelengths. We compare the spectra from the trailing hemisphere with those from the leading, pure-ice hemisphere and with recent laboratory measurements of chlorinated salts, which have distinct spectral signatures at these wavelengths. We find that the signal obtained from Europa's leading hemisphere is 5-10 times lower than the signal obtained from the trailing hemisphere, likely due to a temperature difference between the hemispheres. We discern several spectral features that are present in the trailing hemisphere but not in the spectra of the leading hemisphere, though the explanation for these features is not yet apparent.
  70. Hanley, J., Thompson, G., Roe, H., et al., (including Grundy, W.), 2016, DPS, 48, 502.03, Methane, Ethane, and Nitrogen Liquid Stability on Titan
    Previous studies have shown that the lakes of Titan are composed of methane and/or ethane, but the relative proportions are mostly unclear. Understanding the past and current stability of these lakes requires characterizing the interactions of liquid methane and ethane, along with nitrogen. Previous studies have shown that the freezing point of methane is depressed when mixed with nitrogen. Our cryogenic laboratory setup allows us to explore ices down to 30 K through imaging and transmission spectroscopy. Recent work (see Thompson et al., this conference) discovered that although methane and ethane have similar freezing points, when mixed they can remain liquid down to 72 K. Concurrently with the freezing point measurements we acquire transmission spectra of these mixtures to understand how the spectral features change with concentration and temperature. Any mixing of these two species together will depress the freezing point of the lake below Titan's surface temperature, preventing them from freezing. Also, when ethane ice forms, it freezes on the bottom of the liquid, while methane ice freezes at the top of the liquid, implying ethane ice is denser than the solution, while methane ice is less dense; this holds for all concentrations. We will present new results exploring the ternary system of methane, ethane and nitrogen. In particular we will map out the N2-C2H6 liquidus, as has been done for CH4-N2, as well as explore the effect of nitrogen on the eutectic of the methane-ethane system. This behavior has implications for not only the lakes on the surface of Titan, but also for the evaporation/condensation/cloud cycle in the atmosphere. These results will help interpretation of future observational data, and guide current theoretical models.
  71. DeMeo, F., Carry, B., Polishook, D., et al., (including Moskovitz, N.), 2016, DPS, 48, 510.04, A search for differentiated fragments within asteroid families
    The existence of iron meteorite samples suggest that a number of planetesimals differentiated fully and were subsequently disrupted. Within the current asteroid belt, there is little evidence of bodies that fully differentiated into core, mantle and crust layers (Moskovitz et al. 2008). However, because it has been suggested that differentiation can occur within the interior of a body while the primitive exterior remains intact (Elkins-Tanton et al. 2011), an understanding of the diversity of compositions from differentiated parent bodies is critical. Asteroid families, as constituents of a disrupted progenitor body, provide a glimpse into the interior of their progenitors. However, asteroid families, while spectrally unique from one another, are spectrally similar within each family (Parker et al., 2008, Masiero et al. 2011). Using the Sloan Digital Sky Survey (SDSS) to search for a "needle in a haystack" we identify candidate basaltic and olivine-rich asteroids that are dynamically associated with asteroid families to constrain the amount of differentiation that could have occurred within the parent asteroid. Using FIRE on the 6-meter Magellan Telescope and SpeX on the 3-meter IRTF Telescope we measure near-infrared spectra of more than thirty of these candidates, most of which are part of the Eunomia and Flora families. Results of these observations are presented in this talk.
  72. Schleicher, D., knight, M., 2016, AJ, 152, 89, The Extremely Low Activity Comet 209P/LINEAR During Its Extraordinary Close Approach in 2014
    We present results from our observing campaign of Comet 209P/LINEAR during its exceptionally close approach to Earth during 2014 May, the third smallest perigee of any comet in two centuries. These circumstances permitted us to pursue several studies of this intrinsically faint object, including measurements of gas and dust production rates, searching for coma morphology, and direct detection of the nucleus to measure its properties. Indeed, we successfully measured the lowest water production rates of an intact comet in over 35 years and a corresponding smallest active area, 0.007 km2. When combined with the nucleus size found from radar, this also yields the smallest active fraction for any comet, 0.024%. In all, this strongly suggests that 209P/LINEAR is on its way to becoming an inert object. The nucleus was detected but could not easily be disentangled from the inner coma due to seeing variations and changing spatial scales. Even so, we were able to measure a double-peaked lightcurve consistent with the shorter of two viable rotational periods found by Hergenrother. Radial profiles of the dust coma are quite steep, similar to that observed for some other very anemic comets, and suggest that vaporizing icy grains are present.
  73. Gao, P., Plavchan, P., Gagne, J., et al., (including von Braun, K., Prato, L.), 2016, PASP, 128, 104501, Retrieval of Precise Radial Velocities from Near-infrared High-resolution Spectra of Low-mass Stars
    Given that low-mass stars have intrinsically low luminosities at optical wavelengths and a propensity for stellar activity, it is advantageous for radial velocity (RV) surveys of these objects to use near-infrared (NIR) wavelengths. In this work, we describe and test a novel RV extraction pipeline dedicated to retrieving RVs from low-mass stars using NIR spectra taken by the CSHELL spectrograph at the NASA Infrared Telescope Facility, where a methane isotopologue gas cell is used for wavelength calibration. The pipeline minimizes the residuals between the observations and a spectral model composed of templates for the target star, the gas cell, and atmospheric telluric absorption; models of the line-spread function, continuum curvature, and sinusoidal fringing; and a parameterization of the wavelength solution. The stellar template is derived iteratively from the science observations themselves without a need for separate observations dedicated to retrieving it. Despite limitations from CSHELLs narrow wavelength range and instrumental systematics, we are able to (1) obtain an RV precision of 35 m s-1 for the RV standard star GJ 15 A over a time baseline of 817 days, reaching the photon noise limit for our attained signal-to-noise ratio; (2) achieve 3 m s-1 RV precision for the M giant SV Peg over a baseline of several days and confirm its long-term RV trend due to stellar pulsations, as well as obtain nightly noise floors of 2-6 m s-1 and (3) show that our data are consistent with the known masses, periods, and orbital eccentricities of the two most massive planets orbiting GJ 876. Future applications of our pipeline to RV surveys using the next generation of NIR spectrographs, such as iSHELL, will enable the potential detection of super-Earths and mini-Neptunes in the habitable zones of M dwarfs.
  74. Bannister, M., Kavelaars, J., Petit, J., et al., (including Grundy, W.), 2016, AJ, 152, 70, The Outer Solar System Origins Survey. I. Design and First-quarter Discoveries
    We report the discovery, tracking, and detection circumstances for 85 trans-Neptunian objects (TNOs) from the first 42 deg2 of the Outer Solar System Origins Survey. This ongoing r-band solar system survey uses the 0.9 deg2 field of view MegaPrime camera on the 3.6 m Canada-France-Hawaii Telescope. Our orbital elements for these TNOs are precise to a fractional semimajor axis uncertainty <0.1%. We achieve this precision in just two oppositions, as compared to the normal three to five oppositions, via a dense observing cadence and innovative astrometric technique. These discoveries are free of ephemeris bias, a first for large trans-Neptunian surveys. We also provide the necessary information to enable models of TNO orbital distributions to be tested against our TNO sample. We confirm the existence of a cold kernel of objects within the main cold classical Kuiper Belt and infer the existence of an extension of the stirred cold classical Kuiper Belt to at least several au beyond the 2:1 mean motion resonance with Neptune. We find that the population model of Petit et al. remains a plausible representation of the Kuiper Belt. The full survey, to be completed in 2017, will provide an exquisitely characterized sample of important resonant TNO populations, ideal for testing models of giant planet migration during the early history of the solar system.
  75. Egeland, R., Soon, W., Baliunas, S., et al., (including Hall, J.), 2016, csss, 6, Dynamo Sensitivity In Solar Analogs With 50 Years Of Ca II H & K Activity
    The Sun has a steady 11-year cycle in magnetic activity most well-known by the rising and falling in the occurrence of dark sunspots on the solar disk in visible bandpasses. The 11-year cycle is also manifest in the variations of emission in the Ca II H & K line cores, due to non-thermal (i.e. magnetic) heating in the lower chromosphere. The large variation in Ca II H & K emission allows for study of the patterns of long-term variability in other stars thanks to synoptic monitoring with the Mount Wilson Observatory HK photometers (1966-2003) and Lowell Observatory Solar-Stellar Spectrograph (1994-present). Overlapping measurements for a set of 27 nearby solar-analog (spectral types G0-G5) stars were used to calibrate the two instruments and construct time series of magnetic activity up to 50 years in length. Precise properties of fundamental importance to the dynamo are available from Hipparcos, the Geneva-Copenhagen Survey, and CHARA interferometry. Using these long time series and measurements of fundamental properties, we do a comparative study of stellar "twins" to explore the sensitivity of the stellar dynamo to small changes to structure, rotation, and composition. We also compare this sample to the Sun and find hints that the regular periodic variability of the solar cycle may be rare among its nearest neighbors in parameter space.
  76. Massey, P., Neugent, K., Smart, B., 2016, AJ, 152, 62, A Spectroscopic Survey of Massive Stars in M31 and M33
    We describe our spectroscopic follow-up to the Local Group Galaxy Survey (LGGS) photometry of M31 and M33. We have obtained new spectroscopy of 1895 stars, allowing us to classify 1496 of them for the first time. Our study has identified many foreground stars, and established membership for hundreds of early- and mid-type supergiants. We have also found nine new candidate luminous blue variables and a previously unrecognized Wolf-Rayet star. We republish the LGGS M31 and M33 catalogs with improved coordinates, and including spectroscopy from the literature and our new results. The spectroscopy in this paper is responsible for the vast majority of the stellar classifications in these two nearby spiral neighbors. The most luminous (and hence massive) of the stars in our sample are early-type B supergiants, as expected; the more massive O stars are more rare and fainter visually, and thus mostly remain unobserved so far. The majority of the unevolved stars in our sample are in the 20-40 M range.

    The spectroscopic observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. MMT telescope time was granted by NOAO, through the Telescope System Instrumentation Program (TSIP). TSIP is funded by the National Science Foundation. This paper uses data products produced by the OIR Telescope Data Center, supported by the Smithsonian Astrophysical Observatory.

  77. Baines, E., Dollinger, M., Guenther, E., et al., (including van Belle, G.), 2016, AJ, 152, 66, Spectroscopic and Interferometric Measurements of Nine K Giant Stars
    We present spectroscopic and interferometric measurements for a sample of nine K giant stars. These targets are of particular interest because they are slated for stellar oscillation observations. Our improved parameters will directly translate into reduced errors in the final masses for these stars when interferometric radii and asteroseismic densities are combined. Here, we determine each stars limb-darkened angular diameter, physical radius, luminosity, bolometric flux, effective temperature, surface gravity, metallicity, and mass. When we compare our interferometric and spectroscopic results, we find no systematic offsets in the diameters and the values generally agree within the errors. Our interferometric temperatures for seven of the nine stars are hotter than those determined from spectroscopy with an average difference of about 380 K.
  78. Armstrong, J., Baines, E., Schmitt, H., et al., (including van Belle, G.), 2016, SPIE, 9907, 990702, The Navy Precision Optical Interferometer: an update
    We describe the current status of the Navy Precision Optical Interferometer (NPOI), including developments since the last SPIE meeting. The NPOI group has added stations as far as 250m from the array center and added numerous infrastructure improvements. Science programs include stellar diameters and limb darkening, binary orbits, Be star disks, exoplanet host stars, and progress toward high-resolution stellar surface imaging. Technical and infrastructure projects include on-sky demonstrations of baseline bootstrapping with six array elements and of the VISION beam combiner, control system updates, integration of the long delay lines, and updated firmware for the Classic beam combiner. Our plans to add up to four 1.8 m telescopes are no longer viable, but we have recently acquired separate funding for adding three 1 m AO-equipped telescopes and an infrared beam combiner to the array.
  79. Matter, A., Lopez, B., Antonelli, P., et al., (including van Belle, G., Jasko, A., Kiraly, S.), 2016, SPIE, 9907, 99070A, An overview of the mid-infrared spectro-interferometer MATISSE: science, concept, and current status
    MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 m, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R 30 to R 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.
  80. Kraus, S., Monnier, J., Ireland, M., et al., (including van Belle, G.), 2016, SPIE, 9907, 99071K, Planet Formation Imager (PFI): science vision and key requirements
    The Planet Formation Imager (PFI) project aims to provide a strong scientific vision for ground-based optical astronomy beyond the upcoming generation of Extremely Large Telescopes. We make the case that a breakthrough in angular resolution imaging capabilities is required in order to unravel the processes involved in planet formation. PFI will be optimised to provide a complete census of the protoplanet population at all stellocentric radii and over the age range from 0.1 to 100 Myr. Within this age period, planetary systems undergo dramatic changes and the final architecture of planetary systems is determined. Our goal is to study the planetary birth on the natural spatial scale where the material is assembled, which is the "Hill Sphere" of the forming planet, and to characterise the protoplanetary cores by measuring their masses and physical properties. Our science working group has investigated the observational characteristics of these young protoplanets as well as the migration mechanisms that might alter the system architecture. We simulated the imprints that the planets leave in the disk and study how PFI could revolutionise areas ranging from exoplanet to extragalactic science. In this contribution we outline the key science drivers of PFI and discuss the requirements that will guide the technology choices, the site selection, and potential science/technology tradeoffs.
  81. Ireland, M., Monnier, J., Kraus, S., et al., (including van Belle, G.), 2016, SPIE, 9907, 99071L, Status of the Planet Formation Imager (PFI) concept
    The Planet Formation Imager (PFI) project aims to image the period of planet assembly directly, resolving structures as small as a giant planet's Hill sphere. These images will be required in order to determine the key mechanisms for planet formation at the time when processes of grain growth, protoplanet assembly, magnetic fields, disk/planet dynamical interactions and complex radiative transfer all interact - making some planetary systems habitable and others inhospitable. We will present the overall vision for the PFI concept, focusing on the key technologies and requirements that are needed to achieve the science goals. Based on these key requirements, we will define a cost envelope range for the design and highlight where the largest uncertainties lie at this conceptual stage.
  82. Schmitt, H., Armstrong, J., Restaino, S., et al., (including van Belle, G.), 2016, SPIE, 9907, 99071X, Monitoring a decade of seeing at the NPOI site with quad cell measurements
    As a part of regular operations, the Navy Precision Optical Interferometer (NPOI) uses Narrow Angle Trackers (NAT) for atmospheric tip-tilt correction. This correction is done using a quad cell array for each station, and is based on the error signals measured by these arrays. We compiled NPOI NAT jitter information for the period of 2005 to 2014. Here we investigate the correlation of the NAT jitter between different NPOI stations, and determine a correction for shot-noise induced jitter. We present initial results from the correlation between NAT jitter and quasi simultaneous seeing measurements done with the Lowell Observatory 31" telescope, separated by 500 m. We also discuss some limitations of this technique and future improvements.
  83. Jorgensen, A., Schmitt, H., Armstrong, J., et al., (including van Belle, G.), 2016, SPIE, 9907, 990725, The new classic instrument for the navy precision optical interferometer
    The New Classic instrument was built as a electronics and computer upgrade to the existing Classic beam combiner at the Navy Precision Optical Interferometer (NPOI). The classic beam combiner is able to record 32 of 96 available channels and has a data throughput limitation which results in a low duty cycle. Additionally the computing power of the Classic system limited the amount of fringe tracking that was possible. The New Classic system implements a high-throughput data acquisition system which is capable of recording all 96 channels continuously. It also has a modern high-speed computer for data management and data processing. The computer is sufficiently powerful to implement more sophisticated fringe-tracking algorithms than the Classic system, including multi-baseline bootstrapping. In this paper we described the New Classic hardware and software, including the fringe-tracking algorithm, performance, and the user interface. We also show some initial results from the first 5-station, 4-baseline bootstrapping carried out in January 2015.
  84. Jorgensen, A., Mozurkewich, D., Armstrong, J., et al., (including van Belle, G.), 2016, SPIE, 9907, 99072C, Multi-baseline chain bootstrapping with new classic at the NPOI
    Imaging with optical interferometers requires fringe measurements on baseline long enough to resolve the target. These long baselines typically have low fringe contrast. Phasing them requires fringe tracking on shorter baselines which typically have greater fringe contrast and combining the fringe-tracking signals on the short baselines to phase the long baselines in a baseline bootstrapping configuration. On long resolving baselines coherent integration also becomes necessary in order to shorten the integration time. This paper addresses both the baseline bootstrapping and the coherent integration. The Navy Precision Optical Interferometer (NPOI) is laid out in a way which permits long-baseline phasing from shorter baselines in a multi-baseline scheme. The New Classic instrument for NPOI was designed specifically to implement the multi-baseline bootstrapping capability and multi-baseline observations can now be carried out routinely at the NPOI. This paper provides details about the bootstrapping scheme at NPOI and shows some initial results. We also discuss the bootstrapping error budget, describe our new Bayesian coherent integration algorithm and compare its performance to theory.
  85. Levine, S., DeGroff, W., 2016, SPIE, 9906, 990621, Status and imaging performance of Lowell Observatory's Discovery Channel Telescope in its first year of full science operations
    Lowell Observatory's Discovery Channel Telescope (DCT) is a 4.3-m telescope designed and constructed for optical and near infrared astronomical observation. The DCT is equipped with a cube capable of carrying five instruments along with the wave front sensing and guider systems at the f/6.1 RC focus. The facility formally finished commissioning at the end of 2014. In 2015 the DCT ran in full science operations mode. This report recaps recent progress on the operations and instrument fronts, and then concentrates on the delivered image quality as measured with science imaging data. The system is delivering image quality at or better than the system top level requirements for open loop operations. Corrected to the zenith, the median seeing in the science images from 2015 was 0."93; first quartile seeing was 0.0074. The open loop site contribution to the seeing is roughly 0."40, which is better than the requirements of < 0."47. The FWHM degrades with wind speed at the rate of roughly 0."10/(m/s), and the seeing degrades more with wind speed when the wind is from the East.
  86. Sokal, K., Johnson, K., Indebetouw, R., et al., (including Massey, P.), 2016, ApJ, 826, 194, The Prevalence and Impact of Wolf-Rayet Stars in Emerging Massive Star Clusters
    We investigate Wolf-Rayet (WR) stars as a source of feedback contributing to the removal of natal material in the early evolution of massive star clusters. Despite previous work suggesting that massive star clusters clear out their natal material before the massive stars evolve into the WR phase, WR stars have been detected in several emerging massive star clusters. These detections suggest that the timescale for clusters to emerge can be at least as long as the time required to produce WR stars (a few million years), and could also indicate that WR stars may be providing the tipping point in the combined feedback processes that drive a massive star cluster to emerge. We explore the potential overlap between the emerging phase and the WR phase with an observational survey to search for WR stars in emerging massive star clusters hosting WR stars. We select candidate emerging massive star clusters from known radio continuum sources with thermal emission and obtain optical spectra with the 4 m Mayall Telescope at Kitt Peak National Observatory and the 6.5 m MMT.4 We identify 21 sources with significantly detected WR signatures, which we term emerging WR clusters. WR features are detected in 50% of the radio-selected sample, and thus we find that WR stars are commonly present in currently emerging massive star clusters. The observed extinctions and ages suggest that clusters without WR detections remain embedded for longer periods of time, and may indicate that WR stars can aid, and therefore accelerate, the emergence process.
  87. Johns-Krull, C., McLane, J., Prato, L., et al., (including Skiff, B.), 2016, ApJ, 826, 206, A Candidate Young Massive Planet in Orbit around the Classical T Tauri Star CI Tau
    The 2 Myr old classical T Tauri star CI Tau shows periodic variability in its radial velocity (RV) variations measured at infrared (IR) and optical wavelengths. We find that these observations are consistent with a massive planet in a 9 day period orbit. These results are based on 71 IR RV measurements of this system obtained over five years, and on 26 optical RV measurements obtained over nine years. CI Tau was also observed photometrically in the optical on 34 nights over one month in 2012. The optical RV data alone are inadequate to identify an orbital period, likely the result of star spot and activity-induced noise for this relatively small data set. The infrared RV measurements reveal significant periodicity at 9 days. In addition, the full set of optical and IR RV measurements taken together phase coherently and with equal amplitudes to the 9 day period. Periodic RV signals can in principle be produced by cool spots, hotspots, and reflection of the stellar spectrum off the inner disk, in addition to resulting from a planetary companion. We have considered each of these and find the planet hypothesis most consistent with the data. The RV amplitude yields an M\sin I of 8.1 M Jup; in conjunction with a 1.3 mm continuum emission measurement of the circumstellar disk inclination from the literature, we find a planet mass of 11.3 M Jup, assuming alignment of the planetary orbit with the disk.

    This paper includes data taken at The McDonald Observatory of The University of Texas at Austin.

  88. Massey, P., Evans, K., 2016, ApJ, 826, 224, The Red Supergiant Content of M31*
    We investigate the red supergiant (RSG) population of M31, obtaining the radial velocities of 255 stars. These data substantiate membership of our photometrically selected sample, demonstrating that Galactic foreground stars and extragalactic RSGs can be distinguished on the basis of B - V, V - R two-color diagrams. In addition, we use these spectra to measure effective temperatures and assign spectral types, deriving physical properties for 192 RSGs. Comparison with the solar metallicity Geneva evolutionary tracks indicates astonishingly good agreement. The most luminous RSGs in M31 are likely evolved from 25-30 M stars, while the vast majority evolved from stars with initial masses of 20 M or less. There is an interesting bifurcation in the distribution of RSGs with effective temperatures that increases with higher luminosities, with one sequence consisting of early K-type supergiants, and with the other consisting of M-type supergiants that become later (cooler) with increasing luminosities. This separation is only partially reflected in the evolutionary tracks, although that might be due to the mis-match in metallicities between the solar Geneva models and the higher-than-solar metallicity of M31. As the luminosities increase the median spectral type also increases; I.e., the higher mass RSGs spend more time at cooler temperatures than do those of lower luminosities, a result which is new to this study. Finally we discuss what would be needed observationally to successfully build a luminosity function that could be used to constrain the mass-loss rates of RSGs as our Geneva colleagues have suggested.

    Observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. This paper uses data products produced by the OIR Telescope Data Center, supported by the Smithsonian Astrophysical Observatory.

  89. Gopalan, G., Plavchan, P., van Eyken, J., et al., (including von Braun, K.), 2016, PASP, 128, 084504, Application of the Trend Filtering Algorithm for Photometric Time Series Data
    Detecting transient light curves (e.g., transiting planets) requires high-precision data, and thus it is important to effectively filter systematic trends affecting ground-based wide-field surveys. We apply an implementation of the Trend Filtering Algorithm (TFA) to the 2MASS calibration catalog and select Palomar Transient Factory (PTF) photometric time series data. TFA is successful at reducing the overall dispersion of light curves, however, it may over-filter intrinsic variables and increase instantaneous dispersion when a template set is not judiciously chosen. In an attempt to rectify these issues we modify the original TFA from the literature by including measurement uncertainties in its computation, including ancillary data correlated with noise, and algorithmically selecting a template set using clustering algorithms as suggested by various authors. This approach may be particularly useful for appropriately accounting for variable photometric precision surveys and/or combined data sets. In summary, our contributions are to provide a MATLAB software implementation of TFA and a number of modifications tested on synthetics and real data, summarize the performance of TFA and various modifications on real ground-based data sets (2MASS and PTF), and assess the efficacy of TFA and modifications using synthetic light curve tests consisting of transiting and sinusoidal variables. While the transiting variables test indicates that these modifications confer no advantage to transit detection, the sinusoidal variables test indicates potential improvements in detection accuracy.
  90. Egeland, R., Soon, W., Baliunas, S., et al., (including Hall, J.), 2016, csss, 72, The Solar Dynamo Zoo
    We present composite time series of Ca II H & K line core emission indices of up to 50 years in length for a set of 27 solar-analog stars (spectral types G0-G5; within 10% of the solar mass) and the Sun. These unique data are available thanks to the long-term dedicated efforts of the Mount Wilson Observatory HK project, the Lowell Observatory Solar-Stellar Spectrograph, and the National Solar Observatory/Air Force Research Laboratory/Sacramento Peak K-line monitoring program. The Ca II H & K emission originates in the lower chromosphere and is strongly correlated with the presence of magnetic plage regions in the Sun. These synoptic observations allow us to trace the patterns long-term magnetic variability and explore dynamo behavior over a wide range of rotation regimes and stellar evolution timescales.In this poster, the Ca HK observations are expressed using the Mount Wilson S-index. Each time series is accompanied by a Lomb-Scargle periodogram, fundemental stellar parameters derived from the Geneva-Copenhagen Survey, and statistics derived from the time series including the median S-index value and seasonal and long-term amplitudes. Statistically significant periodogram peaks are ranked according to a new cycle quality metric. We find that clear, simple, Sun-like cycles are the minority in this sample.
  91. Ricker, G., Vanderspek, R., Winn, J., et al., (including Dunham, E.), 2016, SPIE, 9904, 99042B, The Transiting Exoplanet Survey Satellite
    No abstract found.
  92. Kiehlmann, S., Savolainen, T., Jorstad, S., et al., (including Taylor, B.), 2016, A&A, 592, C1, Polarization angle swings in blazars: The case of 3C 279 (Corrigendum)
    No abstract found.
  93. Parker, A., Buie, M., Grundy, W., et al., 2016, ApJL, 825, L9, Discovery of a Makemakean Moon
    We describe the discovery of a satellite in orbit about the dwarf planet (136472) Makemake. This satellite, provisionally designated S/2015 (136472) 1, was detected in imaging data collected with the Hubble Space Telescopes Wide Field Camera 3 on UTC 2015 April 27 at 7.80 0.04 mag fainter than Makemake and at a separation of 0.57. It likely evaded detection in previous satellite searches due to a nearly edge-on orbital configuration, placing it deep within the glare of Makemake during a substantial fraction of its orbital period. This configuration would place Makemake and its satellite near a mutual event season. Insufficient orbital motion was detected to make a detailed characterization of its orbital properties, prohibiting a measurement of the system mass with the discovery data alone. Preliminary analysis indicates that if the orbit is circular, its orbital period must be longer than 12.4 days and must have a semimajor axis 21,000 km. We find that the properties of Makemakes moon suggest that the majority of the dark material detected in the system by thermal observations may not reside on the surface of Makemake, but may instead be attributable to S/2015 (136472) 1 having a uniform dark surface. This dark moon hypothesis can be directly tested with future James Webb Space Telescope observations. We discuss the implications of this discovery for the spin state, figure, and thermal properties of Makemake and the apparent ubiquity of trans-Neptunian dwarf planet satellites.
  94. van Belle, G., Creech-Eakman, M., Ruiz-Velasco, A., 2016, AJ, 152, 16, Bolometric Flux Estimation for Cool Evolved Stars
    Estimation of bolometric fluxes ({F}{{BOL}}) is an essential component of stellar effective temperature determination with optical and near-infrared interferometry. Reliable estimation of {F}{{BOL}} simply from broadband K-band photometry data is a useful tool in those cases were contemporaneous and/or wide-range photometry is unavailable for a detailed spectral energy distribution (SED) fit, as was demonstrated in Dyck et al. Recalibrating the intrinsic {F}{{BOL}} versus observed {F}{{2.2} {{m}}} relationship of that study with modern SED fitting routines, which incorporate the significantly non-blackbody, empirical spectral templates of the INGS spectral library (an update of the library in Pickles) and estimation of reddening, serves to greatly improve the accuracy and observational utility of this relationship. We find that {F}{{BOL}} values predicted are roughly 11% less than the corresponding values predicted in Dyck et al., indicating the effects of SED absorption features across bolometric flux curves.
  95. Ragozzine, D., Grundy, W., Porter, S., 2016, hst, 14581, Spinny TNO Triples: New Analyses of the Spin+Orbit Dynamics of Haumea and 1996 TC36
    We propose to analyze archival data of Trans-Neptunian triples Haumea and 1996 TC36. The analysis requires a new dynamical analysis code focused on providing increased understanding of HST data. This code will allow for fast short-term orbital integration of multiple bodies, including the evolution of their spin periods and will be made publicly available. It will be applied to HST data from 8 Programs to: 1) detect or place upper limits on the photocenter variations of Haumea; 2) detect or place limits on the oblquity-induced precession of Hi'iaka, the outer satellite of Haumea; 3) determine the full n-body orbits of 1996 TC36 and interpret the implication of these results on the formation of this unique system; and 4) investigate the spin dynamics possible in the 1996 TC36 system to explain the elusive photometric variability of this target. The proposed work is a straightforward extension of previous analyses by the proposal team and, by focusing on information-rich triples, will improve our understanding of the formation and evolution of the outer solar system.
  96. Porter, S., Grundy, W., Parker, A., 2016, hst, 14616, Primordial Triplicity: A Census of Hierarchical Triples in the Cold Classical Kuiper Belt
    We propose to observe six wide binaries in the cold classical Kuiper Belt (CCKB) with WFC3 to determine what fraction of them are actually triple systems. The only known hierarchical triple Kuiper Belt object is in the 3:2 Neptune resonance, (47171) 1999 TC36, and so far none have been discovered in the CCKB. Because the CCKB was the least disturbed part of the solar system during giant planet migration, it preserves many primordial aspects of planetesimal formation, including our wide binary targets. If even one of these wide binaries is actually a triple, it would strongly imply that the dominant binary formation mechanism was one that could also create triples. The leading such model is gravitational collapse, which requires that any triples and binaries were formed directly out a single cloud of material. JWST/NIRSpec could further test this theory by comparing the spectra of the three separate objects. In addition, hierarchical triples can uniquely provide independent mass determinations for all three objects. These masses can then be combined with thermal radius measurements from JWST/MIRI and ALMA to determine densities for all three objects in a hierarchical triple. Thus these proposed observations would enable JWST to peer into the interiors of some of the most primordial objects in the outer solar system.
  97. Massey, P., Neugent, K., 2016, hst, 14707, Searching for the Most Massive Stars in M31 and M33
    Our spiral neighbors M31 and M33 can be used as laboratories for testing our theories of massive star evolution. Since massive star evolution depends heavily metallicity, M31 and M33 play a particularly important role in this regard: M31 has a metallicity about 1.5x solar, while M33 possesses a metallicity gradient going from solar in the center to sub-solar in the outer regions. Complete samples of evolved massive stars have been identified in these galaxies, but little is known of their unevolved predecessors, the O-type stars. The upper-left portions of the H-R diagrams of M31 and M33 are virtually empty, not because of the scant numbers of massive stars, but from our lack of knowledge. We are proposing a series of UV SNAPs of the most active star-forming regions in M31 and M33. These regions were previously imaged as part of a Cycle 15 treasury proposal, and have good optical colors, but the UV images were severely affected by charge transfer efficiency issues when the data were taken near the end of WFPC2's life. Our goal is to use photometry from these images to help us identify the most massive stars in these galaxies.
  98. Clayton, G., Bianchi, L., Fitzpatrick, E., et al., (including Massey, P.), 2016, hst, 14761, Mapping the UV Extinction Properties of PHAT Stars in M31
    We propose to construct high-quality UV extinction curves for interstellar dust in M31 by obtaining new low resolution STIS spectra in the G140L and G230L gratings of 15 reddened OB stars in M31 chosen from a newly available list of spectral types. We are choosing sightlines that lie in the footprint of the Panchromatic Hubble Andromeda Treasury (PHAT) survey. Focusing our study on the detailed properties of M31 dust grains via UV spectroscopy with HST/STIS will mean that we can directly connect the variations seen in the UV extinction curves with their environment. By selecting our M31 sightlines in the PHAT survey region, we will be able to probe a variety of potential correlations between dust grains and their environment. These new M31 UV extinction curves along with the gas-to-dust ratio inferred from the Ly-alpha HI column, existing M31 abundance measurements, and the information from the PHAT survey will be inputs to our Maximum Entropy Method (MEM) models to analyze the dust grain populations. In particular, the PHAT survey provides spatially resolved data on the stellar and interstellar environments near to the sightlines being studied as part of this program. We will investigate whether solar (Milky Way) and super-solar (M31) metallicity galaxies have significant variations in their UV extinction properties. This proposal is part of a long-term program to investigate the extinction properties of interstellar dust across a sample of galaxies with different global characteristics such as metallicity and star formation activity.
  99. Bond, H., Ciardullo, R., Jacoby, G., 2016, hst, 14794, Planetary Nebulae in the Open Clusters of M31
    Most planetary nebulae (PNe) are field objects. Precious little is known about their progenitor stars' properties and how they relate to those of the PN. The lone exceptions are the very rare cases where a PN is a member of an open star cluster. Then one can determine the ages, masses, and compositions of the progenitors, providing direct tests of stellar-evolution theory.

    We have recently discovered three PNe belonging to open clusters in M31, the Andromeda Galaxy. Here we propose a set of HST follow-up investigations.

    For the PN in the M31 cluster B477-D075, we know its precise location, and there are excellent photometric data (from the M31 PHAT project) that establish the host cluster's age (350 Myr) and the mass of the PN progenitor star (3.35 Msun). We will use STIS spectroscopy in the UV and optical to measure He, CNO, and alpha-process abundances in the nebula, based on emission-line fluxes and a photoionization code. Our primary aim is to compare the measured abundances with predictions of post-AGB evolution theory. In particular, "hot-bottom burning" is expected to produce enhanced He/H and N/O abundances when the progenitor star is sufficiently massive, but it is uncertain whether this occurs at masses as low as ~3 Msun, or requires masses of at least ~5 Msun. Thus our observations will provide key new constraints on AGB evolution of intermediate-mass stars.

    For two other M31 clusters, B458-D049 and SK044A, whose integrated-light spectra show that a PN is present, we will use WFC3 with an [O III] filter to verify the presence of the PNe, and determine their precise astrometric locations. We will then follow up with STIS spectroscopy in a future HST Cycle.

  100. Michel, P., Cheng, A., Kuppers, M., et al., (including Moskovitz, N., Thirouin, A.), 2016, AdSpR, 57, 2529, Science case for the Asteroid Impact Mission (AIM): A component of the Asteroid Impact & Deflection Assessment (AIDA) mission
    The Asteroid Impact & Deflection Assessment (AIDA) mission is a joint cooperation between European and US space agencies that consists of two separate and independent spacecraft that will be launched to a binary asteroid system, the near-Earth asteroid Didymos, to test the kinetic impactor technique to deflect an asteroid. The European Asteroid Impact Mission (AIM) is set to rendezvous with the asteroid system to fully characterize the smaller of the two binary components a few months prior to the impact by the US Double Asteroid Redirection Test (DART) spacecraft. AIM is a unique mission as it will be the first time that a spacecraft will investigate the surface, subsurface, and internal properties of a small binary near-Earth asteroid. In addition it will perform various important technology demonstrations that can serve other space missions.

    The knowledge obtained by this mission will have great implications for our understanding of the history of the Solar System. Having direct information on the surface and internal properties of small asteroids will allow us to understand how the various processes they undergo work and transform these small bodies as well as, for this particular case, how a binary system forms. Making these measurements from up close and comparing them with ground-based data from telescopes will also allow us to calibrate remote observations and improve our data interpretation of other systems. With DART, thanks to the characterization of the target by AIM, the mission will be the first fully documented impact experiment at asteroid scale, which will include the characterization of the target's properties and the outcome of the impact. AIDA will thus offer a great opportunity to test and refine our understanding and models at the actual scale of an asteroid, and to check whether the current extrapolations of material strength from laboratory-scale targets to the scale of AIDA's target are valid. Moreover, it will offer a first check of the validity of the kinetic impactor concept to deflect a small body and lead to improved efficiency for future kinetic impactor designs.

    This paper focuses on the science return of AIM, the current knowledge of its target from ground-based observations, and the instrumentation planned to get the necessary data.

  101. Hunter, D., Elmegreen, B., Gehret, E., 2016, AJ, 151, 136, Young Star Clusters in the Outer Disks of LITTLE THINGS Dwarf Irregular Galaxies
    We examine FUV images of the LITTLE THINGS sample of nearby dwarf irregular (dIrr) and Blue Compact Dwarf galaxies to identify distinct young regions in their far outer disks. We use these data, obtained with the Galaxy Evolution Explorer satellite, to determine the furthest radius at which in situ star formation can currently be identified. The FUV knots are found at distances from the center of the galaxies of 1-8 disk scale lengths and have ages of slant 20 Myr and masses of 20 M{} to 1 105M{} . The presence of young clusters and OB associations in the outer disks of dwarf galaxies shows that dIrrs do have star formation taking place there in spite of the extreme nature of the environment. Most regions are found where the H I surface density is 1 M{} pc-2, though both the H I and dispersed old stars go out much further. This limiting density suggests a cutoff in the ability to form distinct OB associations and perhaps even stars. We compare the star formation rates in the FUV regions to the average rates expected at their radii and beyond from the observed gas, using the conventional correlation for gas-rich regions. The localized rates are typically 10% of the expected average rates for the outer disks. Either star formation in dIrrs at surface densities < 1 {M} pc-2 occurs without forming distinct associations, or the Kennicutt-Schmidt relation over-predicts the rate beyond this point. In the latter case, the stellar disks in the far-outer parts of dIrrs result from scattering of stars from the inner disk.
  102. Ruiz Velasco, A., van Belle, G., Creech-Eakman, M., 2016, csss, 52, Time-Dependent Diameters Of Mira Variable Stars
    We examined archival data of the Palomar Testbed Inteferometer (PTI) covering a sample of 85 Mira variable stars. The sample contains the three most common types: 65 oxygen-rich (M-type), 11 carbon-rich (C-type) and 9 of the intermediary S-type; Periods range from 150 to 600 days. The PTI database spans over nine years of data; up to 80 epochs for individual stars, spanning multiple pulsation cycles per star. These interferometric angular sizes, along with ancillary measures of distance and bolometric flux, can be used to determine linear size and effective temperature, respectively. Additionally, the PTI data can be divided into narrowband data across the K-band (2.0-2.4 m), allowing separate analysis of spatially resolved continuum and prominent molecular-bandhead regions of these stars, which typically pulsate out of phase.In this posterwe presentpreliminary results that show average sizes changes of 40% for the stellar radii and 44 % for the molecular envelopes.
  103. Hanley, J., Thompson, G., Roe, H., et al., (including Grundy, W.), 2016, tac, 27, Poster 15: Exploring the Composition of Titan's Lakes through Laboratory Experiments
    Previous studies have shown that the lakes of Titan are composed of methane and/or ethane, but the relative proportions are mostly unclear. Understanding the past and current stability of these lakes requires characterizing the interactions of liquid methane and ethane. Mixtures of these hydrocarbons are not fully understood, and a phase diagram has not yet been established. Our current cryogenic laboratory setup reaches temperatures down to 30 K, allowing us to map the full liquidus line (freezing points) of the methane-ethane system as a function of composition and temperature. While pure methane and ethane both freeze around 91 K, our results show that when mixed, the freezing point is depressed down to 72 K for a mixture of 64% methane and 36% ethane. Any mixing of these two species together will depress the freezing point of the lake below Titan's surface temperature, preventing them from freezing. Also, when ethane ice forms, it freezes on the bottom of the liquid, while methane ice freezes at the top of the liquid, implying ethane ice is denser than the solution, while methane ice is less dense; this holds for all concentrations. Concurrently with the phase diagram determination, we have acquired transmission spectra of these mixtures to understand how the spectral features change with concentration and temperature. These results will help interpret future observational data, and guide current theoretical models.
  104. Krick, J., Ingalls, J., Carey, S., et al., (including von Braun, K.), 2016, ApJ, 824, 27, Spitzer IRAC Sparsely Sampled Phase Curve of the Exoplanet Wasp-14B
    Motivated by a high Spitzer IRAC oversubscription rate, we present a new technique of randomly and sparsely sampling the phase curves of hot Jupiters. Snapshot phase curves are enabled by technical advances in precision pointing as well as careful characterization of a portion of the central pixel on the array. This method allows for observations which are a factor of approximately two more efficient than full phase curve observations, and are furthermore easier to insert into the Spitzer observing schedule. We present our pilot study from this program using the exoplanet WASP-14b. Data of this system were taken both as a sparsely sampled phase curve as well as a staring-mode phase curve. Both data sets, as well as snapshot-style observations of a calibration star, are used to validate this technique. By fitting our WASP-14b phase snapshot data set, we successfully recover physical parameters for the transit and eclipse depths as well as the amplitude and maximum and minimum of the phase curve shape of this slightly eccentric hot Jupiter. We place a limit on the potential phase to phase variation of these parameters since our data are taken over many phases over the course of a year. We see no evidence for eclipse depth variations compared to other published WASP-14b eclipse depths over a 3.5 year baseline.
  105. Herrmann, K., Hunter, D., Elmegreen, B., 2016, AJ, 151, 145, Surface Brightness Profiles of Dwarf Galaxies. II. Color Trends and Mass Profiles
    In this second paper of a series, we explore the B - V, U - B, and FUV-NUV radial color trends from a multi-wavelength sample of 141 dwarf disk galaxies. Like spirals, dwarf galaxies have three types of radial surface brightness profiles: (I) single exponential throughout the observed extent (the minority), (II) down-bending (the majority), and (III) up-bending. We find that the colors of (1) Type I dwarfs generally become redder with increasing radius, unlike spirals which have a blueing trend that flattens beyond 1.5 disk scale lengths, (2) Type II dwarfs come in six different flavors, one of which mimics the U shape of spirals, and (3) Type III dwarfs have a stretched S shape where the central colors are flattish, become steeply redder toward the surface brightness break, then remain roughly constant beyond, which is similar to spiral Type III color profiles, but without the central outward bluing. Faint (-9 > MB > -14) Type II dwarfs tend to have continuously red or U shaped colors and steeper color slopes than bright (-14 > MB > -19) Type II dwarfs, which additionally have colors that become bluer or remain constant with increasing radius. Sm dwarfs and BCDs tend to have at least some blue and red radial color trend, respectively. Additionally, we determine stellar surface mass density () profiles and use them to show that the break in generally remains in Type II dwarfs (unlike Type II spirals) but generally disappears in Type III dwarfs (unlike Type III spirals). Moreover, the break in is strong, intermediate, and weak in faint dwarfs, bright dwarfs, and spirals, respectively, indicating that may straighten with increasing galaxy mass. Finally, the average stellar surface mass density at the surface brightness break is roughly 1-2 M pc-2 for Type II dwarfs but higher at 5.9 M pc-2 or 27 M pc-2 for Type III BCDs and dIms, respectively.
  106. Thirouin, A., Sheppard, S., Noll, K., et al., (including Moskovitz, N.), 2016, AJ, 151, 148, Rotational Properties of the Haumea Family Members and Candidates: Short-term Variability.
    Haumea is one of the most interesting and intriguing trans-Neptunian objects (TNOs). It is a large, bright, fast rotator, and its spectrum indicates nearly pure water ice on the surface. It has at least two satellites and a dynamically related family of more than 10 TNOs with very similar proper orbital parameters and similar surface properties. The Haumean family is the only one currently known in the trans-Neptunian belt. Various models have been proposed, but the formation of the family remains poorly understood. In this work, we have investigated the rotational properties of the family members and unconfirmed family candidates with short-term variability studies, and report the most complete review to date. We present results based on five years of observations and report the short-term variability of five family members and seven candidates. The mean rotational periods, from Maxwellian fits to the frequency distributions, are 6.27 1.19 hr for the confirmed family members, 6.44 1.16 hr for the candidates, and 7.65 0.54 hr for other TNOs (without relation to the family). According to our study, there is a possibility that Haumea family members rotate faster than other TNOs; however, the sample of family members is still too limited for a secure conclusion. We also highlight the fast rotation of 2002 GH32. This object has a 0.36 0.02 mag amplitude lightcurve and a rotational period of about 3.98 hr. Assuming 2002 GH32 is a triaxial object in hydrostatic equilibrium, we derive a lower limit to the density of 2.56 g cm-3. This density is similar to Haumeas and much more dense than other small TNO densities.
  107. Fischer, D., Anglada-Escude, G., Arriagada, P., et al., (including Prato, L.), 2016, PASP, 128, 066001, State of the Field: Extreme Precision Radial Velocities
    The Second Workshop on Extreme Precision Radial Velocities defined circa 2015 the state of the art Doppler precision and identified the critical path challenges for reaching 10 cm s-1 measurement precision. The presentations and discussion of key issues for instrumentation and data analysis and the workshop recommendations for achieving this bold precision are summarized here. Beginning with the High Accuracy Radial Velocity Planet Searcher spectrograph, technological advances for precision radial velocity (RV) measurements have focused on building extremely stable instruments. To reach still higher precision, future spectrometers will need to improve upon the state of the art, producing even higher fidelity spectra. This should be possible with improved environmental control, greater stability in the illumination of the spectrometer optics, better detectors, more precise wavelength calibration, and broader bandwidth spectra. Key data analysis challenges for the precision RV community include distinguishing center of mass (COM) Keplerian motion from photospheric velocities (time correlated noise) and the proper treatment of telluric contamination. Success here is coupled to the instrument design, but also requires the implementation of robust statistical and modeling techniques. COM velocities produce Doppler shifts that affect every line identically, while photospheric velocities produce line profile asymmetries with wavelength and temporal dependencies that are different from Keplerian signals. Exoplanets are an important subfield of astronomy and there has been an impressive rate of discovery over the past two decades. However, higher precision RV measurements are required to serve as a discovery technique for potentially habitable worlds, to confirm and characterize detections from transit missions, and to provide mass measurements for other space-based missions. The future of exoplanet science has very different trajectories depending on the precision that can ultimately be achieved with Doppler measurements.
  108. Gagne, J., Plavchan, P., Gao, P., et al., (including von Braun, K., Prato, L.), 2016, ApJ, 822, 40, A High-precision Near-infrared Survey for Radial Velocity Variable Low-mass Stars Using CSHELL and a Methane Gas Cell
    We present the results of a precise near-infrared (NIR) radial velocity (RV) survey of 32 low-mass stars with spectral types K2-M4 using CSHELL at the NASA InfraRed Telescope Facility in the K band with an isotopologue methane gas cell to achieve wavelength calibration and a novel, iterative RV extraction method. We surveyed 14 members of young (25-150 Myr) moving groups, the young field star Eridani, and 18 nearby (<25 pc) low-mass stars and achieved typical single-measurement precisions of 8-15 m s-1with a long-term stability of 15-50 m s-1 over longer baselines. We obtain the best NIR RV constraints to date on 27 targets in our sample, 19 of which were never followed by high-precision RV surveys. Our results indicate that very active stars can display long-term RV variations as low as 25-50 m s-1 at 2.3125 m, thus constraining the effect of jitter at these wavelengths. We provide the first multiwavelength confirmation of GJ 876 bc and independently retrieve orbital parameters consistent with previous studies. We recovered RV variabilities for HD 160934 AB and GJ 725 AB that are consistent with their known binary orbits, and nine other targets are candidate RV variables with a statistical significance of 3-5. Our method, combined with the new iSHELL spectrograph, will yield long-term RV precisions of 5 m s-1 in the NIR, which will allow the detection of super-Earths near the habitable zone of mid-M dwarfs.
  109. Covey, K., Agueros, M., Law, N., et al., 2016, ApJ, 822, 81, Why Are Rapidly Rotating M Dwarfs in the Pleiades so (Infra)red? New Period Measurements Confirm Rotation-dependent Color Offsets From the Cluster Sequence
    Stellar rotation periods (P rot) measured in open clusters have proved to be extremely useful for studying stars angular momentum content and rotationally driven magnetic activity, which are both age- and mass-dependent processes. While P rot measurements have been obtained for hundreds of solar-mass members of the Pleiades, measurements exist for only a few low-mass (<0.5 M ) members of this key laboratory for stellar evolution theory. To fill this gap, we report P rot for 132 low-mass Pleiades members (including nearly 100 with M 0.45 M ), measured from photometric monitoring of the cluster conducted by the Palomar Transient Factory in late 2011 and early 2012. These periods extend the portrait of stellar rotation at 125 Myr to the lowest-mass stars and re-establish the Pleiades as a key benchmark for models of the transport and evolution of stellar angular momentum. Combining our new P rot with precise BVIJHK photometry reported by Stauffer et al. and Kamai et al., we investigate known anomalies in the photometric properties of K and M Pleiades members. We confirm the correlation detected by Kamai et al. between a star's P rot and position relative to the main sequence in the cluster's color-magnitude diagram. We find that rapid rotators have redder (V - K) colors than slower rotators at the same V, indicating that rapid and slow rotators have different binary frequencies and/or photospheric properties. We find no difference in the photometric amplitudes of rapid and slow rotators, indicating that asymmetries in the longitudinal distribution of starspots do not scale grossly with rotation rate.
  110. Ruiz-Velasco, A., Felli, D., Migenes, V., et al., 2016, ApJ, 822, 101, VLBA Surveys of OH Masers in Star-forming Regions. I. Satellite Lines
    Using the Very Long Baseline Array we performed a high-resolution OH maser survey in Galactic star-forming regions (SFRs). We observed all the ground state spectral lines: the main lines at 1665 and 1667 MHz and the satellite lines at 1612 and 1720 MHz. Due to the exceptionality of finding satellite lines in SFRs, we will focus our discussion on those lines. In our sample of 41 OH maser sources, five (12%) showed the 1612 MHz line and ten (24%) showed the 1720 MHz line, with only one source showing both lines. We find that 1720 MHz emission is correlated with the presence of H II regions, suggesting that this emission could be used to diagnose or trace high-mass star formation. We include an analysis of the possible mechanisms that could be causing this correlation as well as assessing the possible relationships between lines in our sample. In particular, the presence of magnetic fields seems to play an important role as we found Zeeman splitting in four of our sources (W75 N, W3(OH), W51 and NGC 7538). Our results have implications for current understanding of the formation of high-mass stars as well as on the masing processes present in SFRs.
  111. Knight, M., Fitzsimmons, A., Kelley, M., et al., 2016, ApJL, 823, L6, Comet 322P/SOHO 1: An Asteroid with the Smallest Perihelion Distance?
    We observed comet 322P/SOHO 1 (P/1999 R1) from the ground and with the Spitzer Space Telescope when it was between 2.2 and 1.2 au from the Sun. These are the first observations of any Solar and Heliospheric Observatory (SOHO)-discovered periodic comet by a non-solar observatory and allow us to investigate its behavior under typical cometary circumstances. 322P appeared inactive in all images. Its light curve suggests a rotation period of 2.8 0.3 hr and has an amplitude 0.3 mag, implying a density of at least 1000 kg m-3, considerably higher than that of any known comet. It has average colors of {g}\prime -{r}\prime =0.52+/- 0.04 and {r}\prime -{I}\prime =0.03+/- 0.06. We converted these to Johnson colors and found that the V - R color is consistent with average cometary colors, but R - I is somewhat bluer; these colors are most similar to V- and Q-type asteroids. Modeling of the optical and IR photometry suggests it has a diameter of 150-320 m and a geometric albedo of 0.09-0.42, with diameter and albedo inversely related. Our upper limits to any undetected coma are still consistent with a sublimation lifetime shorter than the typical dynamical lifetimes for Jupiter-family comets. These results suggest that 322P may be of asteroidal origin and only active in the SOHO fields of view via processes different from the volatile-driven activity of traditional comets. If so, it has the smallest perihelion distance of any known asteroid.

    Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 095.C-0853, with Lowell Observatorys Discovery Channel Telescope, and with Spitzer Space Telescope under program 11104.

  112. Garcia, E., Muterspaugh, M., van Belle, G., et al., (including Strosahl, S., Sanborn, J., Zawicki, S., Sakosky, M.), 2016, PASP, 128, 055004, Vision: A Six-telescope Fiber-fed Visible Light Beam Combiner for the Navy Precision Optical Interferometer
    Visible-light long baseline interferometry holds the promise of advancing a number of important applications in fundamental astronomy, including the direct measurement of the angular diameters and oblateness of stars, and the direct measurement of the orbits of binary and multiple star systems. To advance, the field of visible-light interferometry requires development of instruments capable of combining light from 15 baselines (6 telescopes) simultaneously. The Visible Imaging System for Interferometric Observations at NPOI (VISION) is a new visible light beam combiner for the Navy Precision Optical Interferometer (NPOI) that uses single-mode fibers to coherently combine light from up to six telescopes simultaneously with an image-plane combination scheme. It features a photometric camera for calibrations and spatial filtering from single-mode fibers with two Andor Ixon electron multiplying CCDs. This paper presents the VISION system, results of laboratory tests, and results of commissioning on-sky observations. A new set of corrections have been determined for the power spectrum and bispectrum by taking into account non-Gaussian statistics and read noise present in electron-multipying CCDs to enable measurement of visibilities and closure phases in the VISION post-processing pipeline. The post-processing pipeline has been verified via new on-sky observations of the O-type supergiant binary Orionis A, obtaining a flux ratio of 2.18+/- 0.13 with a position angle of 223.9 1.0 and separation 40.6+/- 1.8 mas over 570-750 nm, in good agreement with expectations from the previously published orbit.
  113. Egeland, R., Soon, W., Baliunas, S., et al., (including Hall, J.), 2016, SPD, 47, 11.03, The Solar Dynamo Zoo
    We present composite time series of Ca II H & K line core emission indices of up to 50 years in length for a set of 27 solar-analog stars (spectral types G0-G5; within ~10% of the solar mass) and the Sun. These unique data are available thanks to the long-term dedicated efforts of the Mount Wilson Observatory HK project, the Lowell Observatory Solar-Stellar Spectrograph, and the National Solar Observatory/Air Force Research Laboratory/Sacremento Peak K-line monitoring program. The Ca II H & K emission originates in the lower chromosphere and is strongly correlated with the presence of magnetic plage regions in the Sun. These synoptic observations allow us to trace the patterns long-term magnetic variability and explore dynamo behavior over a wide range of rotation regimes and stellar evolution timescales.
  114. Egeland, R., Soon, W., Baliunas, S., et al., (including Hall, J.), 2016, SPD, 47, 203.07, Dynamo Sensitivity in Solar Analogs with 50 Years of Ca II H & K Activity
    The Sun has a steady 11-year cycle in magnetic activity most well-known by the rising and falling in the occurrence of dark sunspots on the solar disk in visible bandpasses. The 11-year cycle is also manifest in the variations of emission in the Ca II H & K line cores, due to non-thermal (i.e. magnetic) heating in the lower chromosphere. The large variation in Ca II H & K emission allows for study of the patterns of long-term variability in other stars thanks to synoptic monitoring with the Mount Wilson Observatory HK photometers (1966-2003) and Lowell Observatory Solar-Stellar Spectrograph (1994-present). Overlapping measurements for a set of 27 nearby solar-analog (spectral types G0-G5) stars were used to calibrate the two instruments and construct time series of magnetic activity up to 50 years in length. Precise properties of fundamental importance to the dynamo are available from Hipparcos, the Geneva-Copenhagen Survey, and CHARA interferometry. Using these long time series and measurements of fundamental properties, we do a comparative study of stellar "twins" to explore the sensitivity of the stellar dynamo to small changes to structure, rotation, and composition. We also compare this sample to the Sun and find hints that the regular periodic variability of the solar cycle may be rare among its nearest neighbors in parameter space.
  115. Kiehlmann, S., Savolainen, T., Jorstad, S., et al., (including Taylor, B.), 2016, A&A, 590, A10, Polarization angle swings in blazars: The case of 3C 279
    Context. Over the past few years, on several occasions, large, continuous rotations of the electric vector position angle (EVPA) of linearly polarized optical emission from blazars have been reported. These events are often coincident with high energy -ray flares and they have attracted considerable attention, since they could allow us to probe the magnetic field structure in the -ray emitting region of the jet. The flat-spectrum radio quasar 3C 279 is one of the most prominent examples showing this behaviour.
    Aims: Our goal is to study the observed EVPA rotations and to distinguish between a stochastic and a deterministic origin of the polarization variability.
    Methods: We have combined multiple data sets of R-band photometry and optical polarimetry measurements of 3C 279, yielding exceptionally well-sampled flux density and polarization curves that cover a period of 2008-2012. Several large EVPA rotations are identified in the data. We introduce a quantitative measure for the EVPA curve smoothness, which is then used to test a set of simple random walk polarization variability models against the data.
    Results: 3C 279 shows different polarization variation characteristics during an optical low-flux state and a flaring state. The polarization variation during the flaring state, especially the smooth ~360 rotation of the EVPA in mid-2011, is not consistent with the tested stochastic processes.
    Conclusions: We conclude that, during the two different optical flux states, two different processes govern polarization variation, which is possibly a stochastic process during the low-brightness state and a deterministic process during the flaring activity.

    The measured and processed optical polarization and R-band photometry data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/590/A10

  116. Showalter, M., Weaver, H., Spencer, J., et al., (including Grundy, W.), 2016, DDA, 47, 303.02, Orbital and Rotational Dynamics of Pluto's Small Moons
    Four small moons, Styx, Nix, Kerberos and Hydra, orbit the central binary planet comprising Pluto and Charon. Showalter and Hamilton (Nature 522, 45-49, 2015) analyzed Hubble Space Telescope (HST) data from 2010-2012 to explore some of the dynamical consequences of orbiting a binary planet. They noted evidence for a chaotic rotation of Nix and Hydra, and identified a possible three-body resonance between Styx, Nix and Hydra. We revisit the dynamics of the outer moons based on the data from the New Horizons flyby of July 2015, combined with three more years of HST data. As New Horizons was approaching Pluto, the LORRI camera regularly imaged the moons over a period of approximately 100 days. It also resolved the moons in closeup images, revealing details about the moons' sizes, shapes and surface properties. The LORRI data set has made it possible to derive light curves, rotation rates and pole orientations unambiguously. The moons rotate much faster than they orbit and have high obliquities, suggesting that tidal de-spinning has not played the dominant role in their rotational evolution; impacts may also have played an important role. We will discuss the latest conclusions from a joint analysis of the LORRI and HST data sets, combined with new dynamical simulations. This work was supported by NASA's New Horizons project and by Space Telescope Science Institute.
  117. Showalter, M., Weaver, H., Spencer, J., et al., (including Grundy, W.), 2016, EGUGA, EPSC2016-9490, Orbital and Rotational Dynamics of Pluto's Small Moons
    Four small moons, Styx, Nix, Kerberos and Hydra, orbit the central binary planet comprising Pluto and Charon. Showalter and Hamilton (Nature 522, 45-49, 2015) analyzed Hubble Space Telescope (HST) data from 2010-2012 to explore some of the dynamical consequences of orbiting a binary planet. They noted evidence for a chaotic rotation of Nix and Hydra, and identified a possible three-body resonance between Styx, Nix and Hydra. We revisit the dynamics of the outer moons based on the data from the New Horizons flyby of July 2015, combined with three more years of HST data. As New Horizons was approaching Pluto, the LORRI camera regularly imaged the moons over a period of ~100 days. It also resolved the moons in closeup images, revealing details about the moons' sizes, shapes and surface properties. The LORRI data set has made it possible to derive light curves, rotation rates and pole orientations unambiguously. The moons rotate much faster than they orbit and have high obliquities, suggesting that tidal de-spinning has not played a dominant role in their rotational evolution. We will discuss the latest conclusions from a joint analysis of the LORRI and HST data sets, combined with new dynamical simulations. This work was supported by NASA's New Horizons project and by Space Telescope Science Institute.
  118. Snodgrass, C., Jehin, E., Manfroid, J., et al., (including Knight, M.), 2016, A&A, 588, A80, Distant activity of 67P/Churyumov-Gerasimenko in 2014: Ground-based results during the Rosetta pre-landing phase
    Context. As the ESA Rosetta mission approached, orbited, and sent a lander to comet 67P/Churyumov-Gerasimenko in 2014, a large campaign of ground-based observations also followed the comet.
    Aims: We constrain the total activity level of the comet by photometry and spectroscopy to place Rosetta results in context and to understand the large-scale structure of the comet's coma pre-perihelion.
    Methods: We performed observations using a number of telescopes, but concentrate on results from the 8 m VLT and Gemini South telescopes in Chile. We use R-band imaging to measure the dust coma contribution to the comet's brightness and UV-visible spectroscopy to search for gas emissions, primarily using VLT/FORS. In addition we imaged the comet in near-infrared wavelengths (JHK) in late 2014 with Gemini-S/Flamingos-2.
    Results: We find that the comet was already active in early 2014 at heliocentric distances beyond 4 au. The evolution of the total activity (measured by dust) followed previous predictions. No gas emissions were detected despite sensitive searches.
    Conclusions: The comet maintains a similar level of activity from orbit to orbit, and is in that sense predictable, meaning that Rosetta results correspond to typical behaviour for this comet. The gas production (for CN at least) is highly asymmetric with respect to perihelion, as our upper limits are below the measured production rates for similar distances post-perihelion in previous orbits.

    Based on observations made with ESO telescopes at the La Silla Paranal Observatory under programme IDs 592.C-0924, 093.C-0593, 094.C-0054, and at Gemini South under GS-2014B-Q-15 and GS-2014B-Q-76.

  119. Pasachoff, J., Person, M., Bosh, A., et al., (including Levine, S.), 2016, AJ, 151, 97, Trio of Stellar Occultations by Pluto One Year Prior to New Horizons' Arrival
    We observed occultations by Pluto during a predicted series of events in 2014 July with the 1 m telescope of the Mt. John Observatory in New Zealand. The predictions were based on updated astrometry obtained in the previous months at the USNO, CTIO, and Lowell Observatories. We successfully detected occultations by Pluto of an R = 18 mag star on July 23 (14:23:32 00:00:04 UTC to 14:25:30 00:00:04 UTC), with a drop of 75% of the unocculted stellar signal, and of an R = 17 star on July 24 (11:41:30 00:00:08 UTC to 11:43:28 00:00:08 UTC), with a drop of 80% of the unocculted stellar signal, both with 20 s exposures with our frame-transfer Portable Occultation, Eclipse, and Transit System. Since Pluto had a geocentric velocity of 22.51 km s-1 on July 23 and 22.35 km s-1 on July 24, these intervals yield limits on the chord lengths (surface and lower atmosphere) of 2700 130 km and 2640 250 km, respectively, indicating that the events were near central, and therefore provide astrometric constraints on the prediction method. Our coordinated observations with the 4 m AAT in Australia on July 23 and the 6.5 m Magellan/Clay on Las Campanas, the 4.1 m Southern Astrophysical Research Telescope on Cerro Pachon, the 2.5 m DuPont on Las Campanas (LCO), the 0.6 m SARA-South on Cerro Tololo of the Southeastern Association for Research in Astronomy (SARA), the MPI/ESO 2.2 m on La Silla, and the 0.45 m Cerro Calan telescope and 0.36 telescope in Constitucion in Chile on July 27 and 31, which would have provided higher-cadence observations for studies of Plutos atmosphere, were largely foiled by clouds, but led to detection with the LCO Magellan/Clay and DuPont Telescopes on July 31 of the grazing occultation of a previously unknown 15th-magnitude star, completing the trio of occultations successfully observed and reported in this paper.
  120. Mommert, M., Trilling, D., Borth, D., et al., (including Moskovitz, N.), 2016, AJ, 151, 98, First Results from the Rapid-response Spectrophotometric Characterization of Near-Earth Objects using UKIRT
    Using the Wide Field Camera for the United Kingdom Infrared Telescope (UKIRT), we measure the near-infrared colors of near-Earth objects (NEOs) in order to put constraints on their taxonomic classifications. The rapid-response character of our observations allows us to observe NEOs when they are close to the Earth and bright. Here we present near-infrared color measurements of 86 NEOs, most of which were observed within a few days of their discovery, allowing us to characterize NEOs with diameters of only a few meters. Using machine-learning methods, we compare our measurements to existing asteroid spectral data and provide probabilistic taxonomic classifications for our targets. Our observations allow us to distinguish between S-complex, C/X-complex, D-type, and V-type asteroids. Our results suggest that the fraction of S-complex asteroids in the whole NEO population is lower than the fraction of ordinary chondrites in the meteorite fall statistics. Future data obtained with UKIRT will be used to investigate the significance of this discrepancy.
  121. Haywood, R., Collier Cameron, A., Unruh, Y., et al., (including Llama, J.), 2016, MNRAS, 457, 3637, The Sun as a planet-host star: proxies from SDO images for HARPS radial-velocity variations
    The Sun is the only star whose surface can be directly resolved at high resolution, and therefore constitutes an excellent test case to explore the physical origin of stellar radial-velocity (RV) variability. We present HARPS observations of sunlight scattered off the bright asteroid 4/Vesta, from which we deduced the Sun's activity-driven RV variations. In parallel, the Helioseismic and Magnetic Imager instrument on board the Solar Dynamics Observatory provided us with simultaneous high spatial resolution magnetograms, Dopplergrams and continuum images of the Sun in the Fe I 6173 A line. We determine the RV modulation arising from the suppression of granular blueshift in magnetized regions and the flux imbalance induced by dark spots and bright faculae. The rms velocity amplitudes of these contributions are 2.40 and 0.41 m s-1, respectively, which confirms that the inhibition of convection is the dominant source of activity-induced RV variations at play, in accordance with previous studies. We find the Doppler imbalances of spot and plage regions to be only weakly anticorrelated. Light curves can thus only give incomplete predictions of convective blueshift suppression. We must instead seek proxies that track the plage coverage on the visible stellar hemisphere directly. The chromospheric flux index R^' }_{HK} derived from the HARPS spectra performs poorly in this respect, possibly because of the differences in limb brightening/darkening in the chromosphere and photosphere. We also find that the activity-driven RV variations of the Sun are strongly correlated with its full-disc magnetic flux density, which may become a useful proxy for activity-related RV noise.
  122. Noll, K., Buie, M., Grundy, W., et al., 2016, hst, 14491, Trojan Binary Candidate: A Slow-Rotating Mission Target
    A mission to the unexplored Jupiter Trojans is explicitly called for in the Planetary Decadal and HST observations in early 2016 can influence mission plans for both Discovery and New Frontiers. We propose to observe a Trojan that will be targeted by the step-1 Discovery mission, Lucy. (11351) 1997 TS25 is a Trojan that is notable for having one of the longest known rotation periods of any small body, T=514 h. A possible cause for this long period would be the existence of a tidally locked binary similar to the already-known long-period binary Trojan, (617) Patroclus. If so, the components will be separated by ~0.18 arcsec at lightcurve maximum, resolvable by WFC3. We will coordinate with groundbased observations to schedule near a maximum and thus require only a single orbit to confidently test whether (11351) 1997 TS25 is binary.

    Binary Trojans offer scientific benefits beyond the impact to any specific mission. Orbit-derived mass and density can be used to constrain planetary migration models. Low density is characteristic of bodies found in the dynamically cold Kuiper Belt, a remnant of the solar system's protoplanetary disk. Only one undisputed density has been measured in the Trojans, that of the binary (617) Patroclus, which has a low density of 0.8 g/cm3, similar to the low densities found in the Kuiper Belt. Evidence for or against a possible common origin linking Trojans and KBOs is a key constraint for planetesimal formation and planetary migration models relevant to the solar system and to planetary systems in general.

  123. Polishook, D., Moskovitz, N., Binzel, R., et al., (including Hinkle, M., Thirouin, A.), 2016, Icar, 267, 243, A 2 km-size asteroid challenging the rubble-pile spin barrier - A case for cohesion
    The rubble pile spin barrier is an upper limit on the rotation rate of asteroids larger than 200-300 m. Among thousands of asteroids with diameters larger than 300 m, only a handful of asteroids are known to rotate faster than 2.0 h, all are in the sub-km range (0.6 km). Here we present photometric measurements suggesting that (60716) 2000 GD65, an S-complex, inner-main belt asteroid with a relatively large diameter of 2.3-0.7+0.6km , completes one rotation in 1.9529 0.0002h . Its unique diameter and rotation period allow us to examine scenarios about asteroid internal structure and evolution: a rubble pile bound only by gravity; a rubble-pile with strong cohesion; a monolithic structure; an asteroid experiencing mass shedding; an asteroid experiencing YORP spin-up/down; and an asteroid with a unique octahedron shape results with a four-peak lightcurve and a 3.9 h period. We find that the most likely scenario includes a lunar-like cohesion that can prevent (60716) 2000 GD65 from disrupting without requiring a monolithic structure or a unique shape. Due to the uniqueness of (60716) 2000 GD65, we suggest that most asteroids typically have smaller cohesion than that of lunar regolith.
  124. Holler, B., Young, L., Grundy, W., et al., 2016, Icar, 267, 255, On the surface composition of Triton's southern latitudes
    We present the results of an investigation to determine the longitudinal (zonal) distributions and temporal evolution of ices on the surface of Triton. Between 2002 and 2014, we obtained 63 nights of near-infrared (0.67-2.55 m) spectra using the SpeX instrument at NASA's Infrared Telescope Facility (IRTF). Triton has spectral features in this wavelength region from N2, CO, CH4, CO2, and H2O. Absorption features of ethane (C2H6) and 13CO are coincident at 2.405 m, a feature that we detect in our spectra. We calculated the integrated band area (or fractional band depth in the case of H2O) in each nightly average spectrum, constructed longitudinal distributions, and quantified temporal evolution for each of the chosen absorption bands. The volatile ices (N2, CO, CH4) show significant variability over one Triton rotation and have well-constrained longitudes of peak absorption. The non-volatile ices (CO2, H2O) show poorly-constrained peak longitudes and little variability. The longitudinal distribution of the 2.405 m band shows little variability over one Triton rotation and is 97 44 and 92 44 out of phase with the 1.58 m and 2.35 m CO bands, respectively. This evidence indicates that the 2.405 m band is due to absorption from non-volatile ethane. CH4 absorption increased over the period of the observations while absorption from all other ices showed no statistically significant change. We conclude from these results that the southern latitudes of Triton are currently dominated by non-volatile ices and as the sub-solar latitude migrates northwards, a larger quantity of volatile ice is coming into view.
  125. Mann, A., Feiden, G., Gaidos, E., et al., (including von Braun, K.), 2016, ApJ, 819, 87, Erratum: How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius (ApJ, 804, 64)
    No abstract found.
  126. Weaver, H., Buie, M., Buratti, B., et al., (including Grundy, W.), 2016, Sci, 351, aae0030, The small satellites of Pluto as observed by New Horizons
    The New Horizons mission has provided resolved measurements of Plutos moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of ~40 kilometers for Nix and Hydra and ~10 kilometers for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of ~2. All four moons have high albedos (~50 to 90%) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages of at least 4 billion years. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.
  127. Moore, J., McKinnon, W., Spencer, J., et al., (including Grundy, W.), 2016, Sci, 351, 1284, The geology of Pluto and Charon through the eyes of New Horizons
    NASAs New Horizons spacecraft has revealed the complex geology of Pluto and Charon. Plutos encounter hemisphere shows ongoing surface geological activity centered on a vast basin containing a thick layer of volatile ices that appears to be involved in convection and advection, with a crater retention age no greater than ~10 million years. Surrounding terrains show active glacial flow, apparent transport and rotation of large buoyant water-ice crustal blocks, and pitting, the latter likely caused by sublimation erosion and/or collapse. More enigmatic features include tall mounds with central depressions that are conceivably cryovolcanic and ridges with complex bladed textures. Pluto also has ancient cratered terrains up to ~4 billion years old that are extensionally faulted and extensively mantled and perhaps eroded by glacial or other processes. Charon does not appear to be currently active, but experienced major extensional tectonism and resurfacing (probably cryovolcanic) nearly 4 billion years ago. Impact crater populations on Pluto and Charon are not consistent with the steepest impactor size-frequency distributions proposed for the Kuiper belt.
  128. Grundy, W., Binzel, R., Buratti, B., et al., 2016, Sci, 351, aad9189, Surface compositions across Pluto and Charon
    The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Plutos surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Plutos water ice bedrock was also mapped, with isolated outcrops occurring in a variety of settings. Plutos surface exhibits complex regional color diversity associated with its distinct provinces. Charons color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charons near-infrared spectra reveal highly localized areas with strong ammonia absorption tied to small craters with relatively fresh-appearing impact ejecta.
  129. Kohn, S., Shkolnik, E., Weinberger, A., et al., (including Llama, J.), 2016, ApJ, 820, 2, Searching for Spectroscopic Binaries within Transition Disk Objects
    Transition disks (TDs) are intermediate stage circumstellar disks characterized by an inner gap within the disk structure. To test whether these gaps may have been formed by closely orbiting, previously undetected stellar companions, we collected high-resolution optical spectra of 31 TD objects to search for spectroscopic binaries (SBs). Twenty-four of these objects are in Ophiuchus and seven are within the Coronet, Corona Australis, and Chameleon I star-forming regions. We measured radial velocities for multiple epochs, obtaining a median precision of 400 ms-1. We identified double-lined SB SSTc2d J163154.7-250324 in Ophiuchus, which we determined to be composed of a K7(0.5) and a K9(0.5) star, with orbital limits of a < 0.6 au and P < 150 days. This results in an SB fraction of {0.04}-0.03+0.12 in Ophiuchus, which is consistent with other spectroscopic surveys of non-TD objects in the region. This similarity suggests that TDs are not preferentially sculpted by the presence of close binaries and that planet formation around close binaries may take place over similar timescales to that around single stars.

    This paper is based on data gathered with the 6.5 m Clay Telescope located at Las Campanas Observatory, Chile.

  130. Alvarez-Candal, A., Pinilla-Alonso, N., Ortiz, J., et al., (including Thirouin, A.), 2016, A&A, 586, A155, Absolute magnitudes and phase coefficients of trans-Neptunian objects
    Context. Accurate measurements of diameters of trans-Neptunian objects (TNOs) are extremely difficult to obtain. Thermal modeling can provide good results, but accurate absolute magnitudes are needed to constrain the thermal models and derive diameters and geometric albedos. The absolute magnitude, HV, is defined as the magnitude of the object reduced to unit helio- and geocentric distances and a zero solar phase angle and is determined using phase curves. Phase coefficients can also be obtained from phase curves. These are related to surface properties, but only few are known.
    Aims: Our objective is to measure accurate V-band absolute magnitudes and phase coefficients for a sample of TNOs, many of which have been observed and modeled within the program "TNOs are cool", which is one of the Herschel Space Observatory key projects.
    Methods: We observed 56 objects using the V and R filters. These data, along with those available in the literature, were used to obtain phase curves and measure V-band absolute magnitudes and phase coefficients by assuming a linear trend of the phase curves and considering a magnitude variability that is due to the rotational light-curve.
    Results: We obtained 237 new magnitudes for the 56 objects, six of which were without previously reported measurements. Including the data from the literature, we report a total of 110 absolute magnitudes with their respective phase coefficients. The average value of HV is 6.39, bracketed by a minimum of 14.60 and a maximum of -1.12. For the phase coefficients we report a median value of 0.10 mag per degree and a very large dispersion, ranging from -0.88 up to 1.35 mag per degree.
  131. Hanus, J., Durech, J., Oszkiewicz, D., et al., (including Skiff, B.), 2016, A&A, 586, A108, New and updated convex shape models of asteroids based on optical data from a large collaboration network
    Context. Asteroid modeling efforts in the last decade resulted in a comprehensive dataset of almost 400 convex shape models and their rotation states. These efforts already provided deep insight into physical properties of main-belt asteroids or large collisional families. Going into finer detail (e.g., smaller collisional families, asteroids with sizes 20 km) requires knowledge of physical parameters of more objects.
    Aims: We aim to increase the number of asteroid shape models and rotation states. Such results provide important input for further studies, such as analysis of asteroid physical properties in different populations, including smaller collisional families, thermophysical modeling, and scaling shape models by disk-resolved images, or stellar occultation data. This provides bulk density estimates in combination with known masses, but also constrains theoretical collisional and evolutional models of the solar system.
    Methods: We use all available disk-integrated optical data (I.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. The key ingredient is the support of more that 100 observers who submit their optical data to publicly available databases.
    Results: We present updated shape models for 36 asteroids, for which mass estimates are currently available in the literature, or for which masses will most likely be determined from their gravitational influence on smaller bodies whose orbital deflections will be observed by the ESA Gaia astrometric mission. Moreover, we also present new shape model determinations for 250 asteroids, including 13 Hungarias and three near-Earth asteroids. The shape model revisions and determinations were enabled by using additional optical data from recent apparitions for shape optimization.
  132. Thomas, C., Abell, P., Castillo-Rogez, J., et al., (including Moskovitz, N.), 2016, PASP, 128, 018002, Observing Near-Earth Objects with the James Webb Space Telescope
    The James Webb Space Telescope (JWST) has the potential to enhance our understanding of near-Earth objects (NEOs). We present results of investigations into the observability of NEOs given the nominal observing requirements of JWST on elongation (85-135) and non-sidereal rates (<30 mas s-1). We find that approximately 75% of NEOs can be observed in a given year. However, observers will need to wait for appropriate observing windows. We find that JWST can easily execute photometric observations of meter-sized NEOs that will enhance our understanding of the small NEO population.
  133. Keszthelyi, L., Grundy, W., Stansberry, J., et al., 2016, PASP, 128, 018006, Observing Outer Planet Satellites (Except Titan) with the James Webb Space Telescope: Science Justification and Observational Requirements
    The James Webb Space Telescope (JWST) will allow observations with a unique combination of spectral, spatial, and temporal resolution for the study of outer planet satellites within our Solar System. We highlight the infrared spectroscopy of icy moons and temporal changes on geologically active satellites as two particularly valuable avenues of scientific inquiry. While some care must be taken to avoid saturation issues, JWST has observation modes that should provide excellent infrared data for such studies.
  134. Kelley, M., Woodward, C., Bodewits, D., et al., (including Knight, M.), 2016, PASP, 128, 018009, Cometary Science with the James Webb Space Telescope
    The James Webb Space Telescope (JWST), as the largest space-based astronomical observatory with near- and mid-infrared instrumentation, will elucidate many mysterious aspects of comets. We summarize four cometary science themes especially suited for this telescope and its instrumentation: the drivers of cometary activity, comet nucleus heterogeneity, water ice in comae and on surfaces, and activity in faint comets and main belt asteroids. With JWST, we can expect the most distant detections of gas, especially CO2, in what we now consider to be only moderately bright comets. For nearby comets, coma dust properties can be simultaneously studied with their driving gases, measured simultaneously with the same instrument or contemporaneously with another. Studies of water ice and gas in the distant Solar System will help us test our understanding of cometary interiors, and coma evolution. The question of cometary activity in main belt comets will be further explored with the possibility of a direct detection of coma gas. We explore the technical approaches to these science cases and provide simple tools for estimating comet dust and gas brightness. Finally, we consider the effects of the observatory's non-sidereal tracking limits and provide a list of potential comet targets during the first five years of the mission.
  135. Parker, A., Pinilla-Alonso, N., Santos-Sanz, P., et al., (including Grundy, W.), 2016, PASP, 128, 018010, Physical Characterization of TNOs with the James Webb Space Telescope
    Studies of the physical properties of trans-Neptunian objects (TNOs) are a powerful probe into the processes of planetesimal formation and solar system evolution. James Webb Space Telescope (JWST) will provide unique new capabilities for such studies. Here, we outline where the capabilities of JWST open new avenues of investigation, potentially valuable observations and surveys, and conclude with a discussion of community actions that may serve to enhance the eventual science return of JWST's TNO observations.
  136. Llama, J., Shkolnik, E., 2016, ApJ, 817, 81, Transiting the Sun. II. The Impact of Stellar Activity on Ly Transits
    High-energy observations of the Sun provide an opportunity to test the limits of our ability to accurately measure the properties of transiting exoplanets in the presence of stellar activity. Here we insert the transit of a hot Jupiter into continuous disk integrated data of the Sun in Ly from NASAs Solar Dynamics Observatory/EVE instrument to assess the impact of stellar activity on the measured planet-to-star radius ratio (Rp/R). In 75% of our simulated light curves, we measure the correct radius ratio; however, incorrect values can be measured if there is significant short-term variability in the light curve. The maximum measured value of Rp/R is 50% larger than the input value, which is much smaller than the large Ly transit depths that have been reported in the literature, suggesting that for stars with activity levels comparable to the Sun, stellar activity alone cannot account for these deep transits. We ran simulations without a transit and found that stellar activity cannot mimic the Ly transit of 55 Cancari b, strengthening the conclusion that this planet has a partially transiting exopshere. We were able to compare our simulations to more active stars by artificially increasing the variability in the Solar Ly light curve. In the higher variability data, the largest value of Rp/R we measured is <3 the input value, which again is not large enough to reproduce the Ly transit depth reported for the more active stars HD 189733 and GJ 436, supporting the interpretation that these planets have extended atmospheres and possible cometary tails.
  137. Polishook, D., Moskovitz, N., 2016, IAUS, 318, 193, Searching for color variation on fast rotating asteroids with simultaneous V-J observations
    Boulders, rocks and regolith on fast rotating asteroids (<2.5 hours) are modeled to slide towards the equator due to a strong centrifugal force and a low cohesion force. As a result, regions of fresh subsurface material can be exposed. Therefore, we searched for color variation on small and fast rotating asteroids. We describe a novel technique in which the asteroid is simultaneously observed in the visible and near-IR wavelength range. In this technique, brightness changes due to atmospheric extinction effects can be calibrated across the visible and near-IR images. We use V- and J-band filters since the distinction in color between weathered and unweathered surfaces on ordinary chondrite-like bodies is most prominent at these wavelengths and can reach ~25%. To test our method, we observed 3 asteroids with Cerro Tololo's 1.3 m telescope. We find ~5% variation of the mean V-J color, but do not find any clearly repeating color signature through multiple rotations. This suggests that no landslides occurred within the timescale of space weathering, or that Landslides occurred but the exposed patches are too small for the measurements' uncertainty.
  138. Flagg, L., Shkolnik, E., Weinberger, A., et al., 2016, IAUS, 314, 65, A New, Young, Low-Mass Spectroscopic Binary Without a Home
    We have discovered that 2MASS 08355977-3042306 is an accreting K7, double-lined, spectroscopic binary younger than ~20 Myr. The age of a dispersed young star can best be determined if it is a member of a known young moving group. However, the three dimensional space velocities (UVW) we calculate using radial velocity measurements, proper motions, and plausible photometric distances make membership in any known young moving group unlikely.
  139. Plavchan, P., Gao, P., Gagne, J., et al., (including Prato, L., von Braun, K.), 2016, IAUS, 314, 286, Precise Near-Infrared Radial Velocities
    We present the results of two 2.3 m near-infrared (NIR) radial velocity (RV) surveys to detect exoplanets around 36 nearby and young M dwarfs. We use the CSHELL spectrograph (R ~ 46,000) at the NASA InfraRed Telescope Facility (IRTF), combined with an isotopic methane absorption gas cell for common optical path relative wavelength calibration. We have developed a sophisticated RV forward modeling code that accounts for fringing and other instrumental artifacts present in the spectra. With a spectral grasp of only 5 nm, we are able to reach long-term radial velocity dispersions of ~20-30 m s-1 on our survey targets.
  140. Lorenzi, V., Pinilla-Alonso, N., Licandro, J., et al., (including Grundy, W.), 2016, A&A, 585, A131, The spectrum of Pluto, 0.40-0.93 m. I. Secular and longitudinal distribution of ices and complex organics
    Context. During the past 30 years the surface of Pluto has been characterized and its variability monitored through continuous near-infrared spectroscopic observations. But in the visible range only a few data are available.
    Aims: The aim of this work is to define Pluto's relative reflectance in the visible range to characterize the different components of its surface, and to provide ground based observations in support of the New Horizons mission.
    Methods: We observed Pluto on six nights between May and July 2014 with the imager/spectrograph ACAM at the William Herschel Telescope (La Palma, Spain). The six spectra obtained cover a whole rotation of Pluto (Prot = 6.4 days). For all the spectra, we computed the spectral slope and the depth of the absorption bands of methane ice between 0.62 and 0.90 m. To search for shifts in the center of the methane bands, which are associated with dilution of CH4 in N2, we compared the bands with reflectances of pure methane ice.
    Results: All the new spectra show the methane ice absorption bands between 0.62 and 0.90 m. Computation of the depth of the band at 0.62 m in the new spectra of Pluto and in the spectra of Makemake and Eris from the literature, allowed us to estimate the Lambert coefficient at this wavelength at temperatures of 30 K and 40 K, which has never been measured before. All the detected bands are blueshifted with respect to the position for pure methane ice, with minimum shifts correlated to the regions where the abundance of methane is higher. This could be indicative of a dilution of CH4:N2 that is more saturated in CH4. The longitudinal and secular variations in the parameters measured in the spectra are in accordance with results previously reported in the literature and with the distribution of the dark and bright materials that show the Pluto's color maps from New Horizons.
  141. Cigan, P., Young, L., Cormier, D., et al., (including Hunter, D.), 2016, AJ, 151, 14, Herschel Spectroscopic Observations of Little Things Dwarf Galaxies
    We present far-infrared (FIR) spectral line observations of five galaxies from the Little Things sample: DDO 69, DDO 70, DDO 75, DDO 155, and WLM. While most studies of dwarfs focus on bright systems or starbursts due to observational constraints, our data extend the observed parameter space into the regime of low surface brightness dwarf galaxies with low metallicities and moderate star formation rates. Our targets were observed with Herschel at the [C II] 158 m, [O I] 63 m, [O III] 88 m, and [N II] 122 m emission lines using the PACS Spectrometer. These high-resolution maps allow us for the first time to study the FIR properties of these systems on the scales of larger star-forming complexes. The spatial resolution in our maps, in combination with star formation tracers, allows us to identify separate photodissociation regions (PDRs) in some of the regions we observed. Our systems have widespread [C II] emission that is bright relative to continuum, averaging near 0.5% of the total infrared (TIR) budgethigher than in solar-metallicity galaxies of other types. [N II] is weak, suggesting that the [C II] emission in our galaxies comes mostly from PDRs instead of the diffuse ionized interstellar medium (ISM). These systems exhibit efficient cooling at low dust temperatures, as shown by ([O I]+[C II])/TIR in relation to 60 m/100 m, and low [O I]/[C II] ratios which indicate that [C II] is the dominant coolant of the ISM. We observe [O III]/[C II] ratios in our galaxies that are lower than those published for other dwarfs, but similar to levels noted in spirals.
  142. Elmegreen, B., Hunter, D., Rubio, M., et al., 2016, AAS, 227, 111.06, Star Formation at Low Metallicity in Local Dwarf Irregular Galaxies
    The radial profiles of star formation rates and surface mass densities for gas and stars have been compiled for 20 local dwarf irregular galaxies and converted into disk scale heights and Toomre Q values. The scale heights are relatively large compared to the galaxy sizes (~0.6 times the local radii) and generally increase with radius in a flare. The gaseous Q values are high, ~4, at most radii and even higher for the stars. Star formation proceeds even with these high Q values in a normal exponential disk as viewed in the far ultraviolet. Such normal star formation suggests that Q is not relevant to star formation in dIrrs. The star formation rate per unit area always equals approximately the gas surface density divided by the midplane free fall time with an efficiency factor of about 1% that decreases systematically with radius in approximate proportion to the gas surface density. We view this efficiency variation as a result of a changing molecular fraction in a disk where atomic gas dominates both stars and molecules. In a related study, CO observations with ALMA of star-forming regions at the low metallicities of these dwarfs, which averages 13% solar, shows, in the case of the WLM galaxy, tiny CO clouds inside much larger molecular and atomic hydrogen envelopes. The CO cloud mass fraction within the molecular region is only one percent or so. Nevertheless, the CO clouds have properties that are similar to solar neighborhood clouds: they satisfy the size-linewidth relation observed in the LMC, SMC, and other local dwarfs where CO has been observed, and the same virial mass versus luminosity relation. This uniforming of CO cloud properties seems to be the result of a confining pressure from the weight of the overlying molecular and atomic shielding layers. Star formation at low metallicity therefore appears to be a three dimensional process independent of 2D instabilities involving Q, in highly atomic gas with relatively small CO cores, activated at a rate given by the local average midplane density.
  143. Schindler, K., Nye, R., Rosenthal, P., 2016, AAS, 227, 114.04, Lowell Observatory's 24-inch Clark Refractor: Its History and Renovation
    In 1895, Percival Lowell hired eminent telescope maker Alvan G. Clark to build a 24-inch refractor. Lowell intended the telescope intitally for observing Mars in support of his controversial theories about life on that planet. Clark finished the telescope within a year and at a cost of $20,000. Lowell and his staff of assistants and astronomers began observing through it on July 23, 1896, setting off a long and productive career for the telescope.While Lowell's Mars studies dominated early work with the Clark, V.M. Slipher by the 1910s was using it to observe planetary rotations and atmospheric compositions. He soon revolutionized spectroscopic studies, gathering excruciatingly long spectra - some in excess of 40 hours - of the so-called white nebula and determining startling radial velocities, evidence of an expanding universe. In the 1960s, scientists and artists teamed up on the Clark and created detailed lunar maps in support of the Apollo program.In recent decades, the Clark has played a central role in the education programs at Lowell, with general public audiences, students, and private groups all taking advantage of this unique resource.With this nearly 120 years of contant use, the Clark had been wearing down in recent years. The telescope was becoming more difficult to move, old electrical wiring in the dome was a fire hazard, and many of the telescope's parts needed to be repaired or replaced.In 2013, Lowell Observatory began a fundraising campaign, collecting $291,000 to cover the cost of dome and telescope renovation. Workers removed the entire telescope mount and tube assembly from the dome, examining every part from tube sections to individuals screws. They also stabilized the dome, adding a water vapor barrier and new outer wall while reinforcing the upper dome. The project lasted from January, 2014 through August, 2015. The facility reopened for daytime tours in September, 2015 and evening viewing the following month.
  144. Llama, J., Shkolnik, E., 2016, AAS, 227, 128.01, Stellar activity effects on high energy exoplanet transits
    High energy (X-ray / UV) observations of transiting exoplanets have revealed the presence of extended atmospheres around a number of systems. At such high energies, stellar radiation is absorbed high up in the planetary atmosphere, making X-ray and UV observations a potential tool for investigating the upper atmospheres of exoplanets. At these high energies, stellar activity can dramatically impact the observations. At short wavelengths the stellar disk appears limb-brightened, and active regions appear as extended bright features that evolve on a much shorter timescale than in the optical making it difficult . These features impact both the transit depth and shape, affecting our ability to measure the true planet-to-star radius ratio.I will show results of simulated exoplanet transit light curves using Solar data obtained in the soft X-ray and UV by NASA's Solar Dynamics Observatory to investigate the impact of stellar activity at these wavelengths. By using a limb-brightened transit model coupled with disk resolved Solar images in the X-ray, extreme- and far-UV I will show how both occulted and unocculted active regions can mimic an inflated planetary atmosphere by changing the depth and shape of the transit profile. I will also show how the disk integrated Lyman-alpha Solar irradiance varies on both short and long timescales and how this variability can impact our ability to recover the true radius ratio of a transiting exoplanet.Finally, I will present techniques on how to overcome these effects to determine the true planet-to-star radius in X-ray and UV observations.
  145. Maier, E., Hunter, D., Chien, L., 2016, AAS, 227, 135.13, Turbulence and Star Formation in a Sample of Spiral Galaxies
    We investigate turbulent gas motions in spiral galaxies and their importance to star formation in far outer disks, where the column density is typically far below the critical value for spontaneous gravitational collapse. Following the methods of Burkhart et al. (2010) as applied to the Small Magellanic Cloud, we use the third and fourth statistical moments, skewness and kurtosis, which are indicators of structures caused by turbulence, to examine the integrated neutral hydrogen (H) column density of a sample of spiral galaxies selected from The H Nearby Galaxy Survey (THINGS, Walter et al. 2008). We examine the kurtosis and skewness values of each galaxy as a whole, as well as their variation as a function of radius and in discrete sub-regions defined by a square, moving 'kernel,' essentially splitting each galaxy into a grid. We then create individual grid maps of kurtosis and skewness for each galaxy. To investigate the relation between these moments and star formation, we compare these maps with maps of each galaxy's far-ultraviolet (FUV) image, taken by the Galaxy Evolution Explorer (GALEX) satellite. We find that the moments are largely uniform across the galaxies: the variation does not appear to trace any star forming regions. This may, however, be due to the spatial resolution of our analysis, which could potentially limit the scale of turbulent motions to at most ~700 pc. From our analysis of the comparison between the two moments themselves, we find that the gas motions in our sample galaxies are largely supersonic. This analysis shows that Burkhart et al. (2010)'s methods may be applied not just to dwarf galaxies but normal spiral galaxies as well.We acknowledge the NSF for their funding of this work through their Research Experience for Undergraduates (REU) program (Grant No. AST-1461200).
  146. Adams, A., Boyajian, T., von Braun, K., 2016, AAS, 227, 138.04, Stellar Angular Diameter Relations for Microlensing Surveys
    Determining the physical properties of microlensing events depends on having accurate angular radii of the source star. Using long-baseline optical interferometry we are able to determine the angular sizes of nearby stars with uncertainties less than 2 percent. We present empirical estimates of angular diameters for both dwarfs/subgiants and giant stars as functions of five color indices which are relevant to planned microlensing surveys. We find in all considered colors that metallicity does not play a statistically significant role in predicting stellar size for the samples of stars considered.
  147. Ruiz-Velasco, A., van Belle, G., Creech-Eakman, M., 2016, AAS, 227, 144.18, Direct Measures of Time-Dependent Diameters and Temperatures of Mira Variables
    We examine archival data of the Palomar Testbed Inteferometer (PTI) covering a sample of 85 Mira variable stars. The sample contains the three most common types: 65 oxygen-rich (M-type), 11 carbon-rich (C-type) and 9 of the intermediary S-type; periods ranging from 150 to 600 days. The PTI database spans over nine years of data; up to 80 epochs for individual stars, spanning multiple pulsation cycles per star. These interferometric angular sizes, along with ancillary measures of distance and bolometric flux, can be used to determine linear size and effective temperature, respectively. Additionally, the PTI data can be divided into narrowband data across the K-band (2.0-2.4 m), allowing separate analysis of spatially resolved continuum and prominent molecular-bandhead regions of these stars, which typically pulsate out of phase. Preliminary results show average sizes changes of 40% for the stellar radii and 44 % for the molecular envelopes.
  148. McIntosh, M., de Propris, R., West, M., 2016, AAS, 227, 235.18, Cluster Position Angle Alignments in the CLASH Survey
    There exists strong evidence for nearby brightest cluster galaxies (BCGs) to exhibit preferential orientation with respect to their surroundings. Primarily, we see these bright member galaxies aligning themselves with the cluster's principal axis. We have examined the orientations of the 25 CLASH Survey galaxy clusters to see whether this tendency for BCGs to share the same major axis orientation as their host cluster extends to galaxy clusters at redshifts up to 0.9. We find evidence of preferential orientations existing in clusters at these redshifts. The significance of this finding for theories of the formation of clusters are discussed. Supported by NSF Grant #1358980 and the MA Space Grant Consortium.
  149. Wright-Garba, N., Prato, L., Allen, T., et al., (including Biddle, L., Avilez, I.), 2016, AAS, 227, 236.05, The DF Tau T Tauri Binary
    Most stars form in multiple systems. Despite this, there are observed differences in properties of stars formed within close proximity of each other. This makes obtaining images and spectra of resolved components in systems for individual analysis desirable. DF Tau is a young, low-mass, visual binary in the Taurus star-forming region with a semi-major axis of ~13 AU. With Adaptive Optics, we are able to acquire high-resolution spectroscopic and imaging data of the primary and secondary stars. We find the primary and secondary differ in a number of characteristics, including vsini and disk presence. This is in spite of the stars having identical spectral types. We are in the process of mapping the ~44-year orbit, and here we present our latest imaging and spectroscopic data.
  150. Allen, T., Prchlik, J., Megeath, S., et al., (including Prato, L., Biddle, L., Wright-Garba, N.), 2016, AAS, 227, 236.11, Properties of Young Stars in Nearby SFRs: Cepheus, Ophiuchus and Taurus
    We study the properties of young stars in several nearby star formation regions. Our approach examines both the aggregate properties of large samples of young stars and the detailed properties of a smaller sample of individual stars. The large aggregate sample helps our statistical understanding of how while studying individual young stars in detail informs our interpretation of the larger data set. The specific star formation regions we have been studying include Cep OB3b, a large cluster of thousands of young stars as well as Taurus and Ophiuchus, both smaller star formation regions that are close enough to examine individual stars in detail. We use a number of instruments that span much of the electromagnetic spectrum including the Discovery Channel Telescope in the ultraviolet and visible and Keck in the infrared. For the young stars in the Cep OB3b region we examine the X-ray and accretion properties. For the young stars in Taurus and Ophiuchus, we estimate properties, such as vsini, magnetic field strength, effective temperature and presence (or lack) of a disk.
  151. Evans, K., Massey, P., 2016, AAS, 227, 239.04, A Runaway Red Supergiant in M31
    A significant percentage of OB stars are runaways, so we should expect a similar percentage of their evolved descendants to also be runaways. However, recognizing such stars presents its own set of challenges, as these older, more evolved stars will have drifted further from their birthplace, and thus their velocities might not be obviously peculiar. Several Galactic red supergiants (RSGs) have been described as likely runaways, based upon the existence of bow shocks, including Betelgeuse. Here we announce the discovery of a runaway RSG in M31, based upon a 300 km s-1 discrepancy with M31's kinematics. The star is found about 21 (4.6 kpc) from the plane of the disk, but this separation is consistent with its velocity and likely age (10 Myr). The star, J004330.06+405258.4, is an M2 I, with MV=-5.7, log L/L=4.76, an effective temperature of 3700 K, and an inferred mass of 12-15 M. The star may be a high-mass analog of the hypervelocity stars, given that its peculiar space velocity is probably 400-450 km s-1, comparable to the escape speed from M31's disk. K. A. E.'s work was supported by the NSF's Research Experience for Undergraduates program through AST-1461200, and P. M.'s was partially supported by the NSF through AST-1008020 and through Lowell Observatory.
  152. Karnath, N., Allen, T., Prchlik, J., et al., 2016, AAS, 227, 240.23, A Hectochelle Radial Velocity Survey of Cep OB3b: An ONC like cluster at late gas dispersal phase
    Cep OB3b is a young (~3-5 Myr), late gas dispersal cluster of roughly 3000 members broken into two sub-clusters (Eastern and Western) at a distance of 700pc; it is a rare example of nearby cluster in the late stages of gas dispersal and appears to be a more evolved analog to the Orion Nebular Cluster. As part of an ongoing multi wavelength study, we focus on Hectochelle data from the MMT to measure the radial velocities of 499 stars. After removing binaries, outliers, and imposing a minimum R value to the cross correlation, we obtain radial velocities of 57 previously identified members, with an average error of 1.7 km/s. There is no observed variation in radial velocity across the cluster in right ascension or declination. The preferred mechanism for this type of kinematic evolution is that any initial kinematic structure from formation may have been erased and that minimal or no rotation is present in the cluster. However, the Eastern sub-cluster, containing the most massive star in the field, an O7 star, has a higher velocity dispersion than the Western sub-cluster, which contains several B stars. We will compare these results to CO maps of the residual gas in the cluster and discuss possible reasons for this difference. Finally, we will assess whether the cluster is bound or in a state of expansion.
  153. van Belle, G., Prato, L., 2016, AAS, 227, 247.01, The Lowell Observatory Predoctoral Scholar Program
    Lowell Observatory is pleased to solicit applications for our Predoctoral Scholar Fellowship Program. Now beginning its eighth year, this program is designed to provide unique research opportunities to graduate students in good standing, currently enrolled at Ph.D. granting institutions. Lowell staff research spans a wide range of topics, from astronomical instrumentation, to icy bodies in our solar system, exoplanet science, stellar populations, star formation, and dwarf galaxies. The Observatory's new 4.3 meter Discovery Channel Telescope has successfully begun science operations and we anticipate the commissioning of new instruments in 2015, making this a particularly exciting time in our history. Student research is expected to lead to a thesis dissertation appropriate for graduation at the doctoral level at the student's home institution. The Observatory provides competitive compensation and full benefits to student scholars. For more information, see http://www2.lowell.edu/rsch/predoc.php and links therein. Applications for Fall 2016 are due by May 1, 2016.
  154. Sokal, K., Johnson, K., Indebetouw, R., et al., (including Massey, P.), 2016, AAS, 227, 304.06, An Evolutionary Transition of Massive Star Clusters: Emerging Wolf-Rayet Clusters
    It is not yet well understood how massive star clusters emerge from their natal material, despite huge implications for the fate of the cluster itself and potentially to the entire host galaxy. While this evolutionary transition from embedded natal clusters to cleared-out optical star clusters is clearly the result of the star formation, it is important to understand what physical processes are contributing to this feedback. We highlight an overlooked yet potentially significant source of feedback -- Wolf-Rayet (WR) stars. While a massive star cluster is expected to have cleared out before the WR phase, we have identified an emerging cluster, S26 in NGC 4449, that hosts a substantial population of evolved WRs and shows signs of ongoing feedback. We follow up this significant discovery with an observational survey to search for more sources undergoing this evolutionary phase. We obtain optical spectra of a sample of radio-selected targets (characteristics chosen to identify those early in their evolution) to look for WR signatures; we term successful detections as 'emerging WR clusters'. We evaluate the importance of WR ionization and feedback on massive star cluster evolution and find that while many massive star clusters may emerge quickly, it seems that some might require additional feedback from the WRs.
  155. Person, M., MIT-Williams Occulation Group, HIPO Instrument Group, et al., 2016, AAS, 227, 320.06, Pluto's Atmosphere from the 29 June 2015 Occultation: SOFIA Airborne Results
    After an extensive prediction effort, the 29 June 2015 occultation by Pluto was observed from both airborne (Stratospheric Observatory for Infrared Astronomy - SOFIA) and numerous ground-based telescopes (Bosh et al. 2015, in prep.). Real-time prediction updates allowed placement of the SOFIA telescope with its four detectors deep within the central-flash region of the atmospheric occultation. Fortuitously, the Mount John University Observatory (Lake Tekapo, New Zealand) was also within the central-flash region. This happenstance allowed for direct mutual calibration of the SOFIA data with the ground-based data in multiple central-flash detections in several colors from each facility resulting in a full maping of the central-flash evolute.Combining all of the data allows for a precise measurement of the SOFIA flight path through the shadow, and direct measurement of Pluto's atmospheric shadow size.We will examine and discuss the central-flash signatures from the deepest pass yet recorded through a Pluto central flash. The relative orientations and asymmetries in the various central flash data allow us to use them to tightly constrain the lower atmospheric ellipticity and orientation of likely winds with respect to Pluto's figure. The ratio of the two separate central flashes (airborne and ground-based) is also a strong constraint on the geometric solution for the full occultation data set, and the absolute height of the central flashes with respect to those expected for a clear isothermal atmosphere places constraints on haze densities and thermal gradients in Pluto's lower atmosphere. We can also compare the central-flash signatures in several colors to establish bounds on haze-particle sizes in the lower atmosphere.SOFIA is jointly operated by the Universities Space Research Association, Inc. (USRA), under NASA contract NAS2-97001, and the Deutsches SOFIA Institut (DSI) under DLR contract 50 OK 0901 to the University of Stuttgart. Support for this work was provided, in part, by NASA grants SSO NNX15AJ82G (Lowell Observatory), PA NNX10AB27G (MIT), and PA NNX12AJ29G (Williams College), as well as the National Research Foundation of South Africa, and the NASA SOFIA Cycle 3 grant NAS2-97001 issued by USRA.
  156. Apala, E., Soderberg, A., West, M., 2016, AAS, 227, 340.03, Gamma Ray Burst 150518a measured at different wavelengths
    Gamma Ray Burst (GRB's), extremely energetic flashes of Gamma Rays, are caused by either deaths of massive unstable stars or colliding binary neutron stars. A unique burst, GRB 150518a, had two recorded bursts fifteen minutes apart which is very rare and is considered to be ultra-long, lasting around thirty minutes total and is associated with a Supernova explosion. GBR 150518a is also extremely close compared to the average burst being measured to have a redshift of .2, this is important to note because GRB's measuring less than a redshift of .3 only are seen every ten years. Gamma rays are emitted by supernovae, neutron stars, black holes, and quasars and by studying GRB's it allows us to see more deeply into how these objects function. The first few days of GRB 150518as' detected afterglow was plotted in different wavelengths, including optical, x-ray, radio, and infrared, in flux verses time. Data is continuously being added as time goes on. This research is funded by the NSF, grant number 1358990.
  157. Kerkstra, B., Lomax, J., Bjorkman, K., et al., (including Skiff, B.), 2016, AAS, 227, 343.02, PRISM Polarimetry of Massive Stars
    We present the early results from our long-term, multi-epoch filter polarization survey of massive stars in and around young Galactic clusters. These BVRI polarization data were obtained using the PRISM instrument mounted on the 1.8m Perkins Telescope at Lowell Observatory. We first detail the creation of our new semi-automated polarization data reduction pipeline that we developed to process these data. Next, we present our analysis of the instrumental polarization properties of the PRISM instrument, via observations of polarized and unpolarized standard stars. Finally, we present early results on the total and intrinsic polarization behavior of several isolated, previously suggested classical Be stars, and discuss these results in the context of the larger project.BK acknowledges support from a NSF/REU at the University of Oklahoma. This program was also supported by NSF-AST 11411563, 1412110, and 1412135.
  158. van Belle, G., Pilyavsky, G., von Braun, K., et al., 2016, AAS, 227, 345.12, The PTI Giant Star Angular Size Survey: Effective Temperatures & Linear Radii
    We report new interferometric angular diameter observations of over 200 giant stars observed with the Palomar Testbed Interferometer (PTI). These angular diameters are combined with bolometric fluxes derived from detailed spectral energy distribution (SED) fits, to produce robust estimates of effective temperature (TEFF). These SED fits include reddening estimates and are based upon fits of empirical spectral templates to literature photometry, and narrow-band photometry obtained at the Lowell 31" telescope. The 58 nights of 31" observing have produced over 45,000 new photometric data points on these stars, allowing for flux and reddening determination with unprecident precision. Over the range from G5III to M8III, TEFF estimates are precise to 50K per spectral type. Radius estimates are limited by the improved Hipparcos estimates of van Leeuwen (2007) and are typically ~10% per star.
  159. Garcia, E., Muterspaugh, M., van Belle, G., et al., 2016, AAS, 227, 345.13, VISION: A Six-Telescope Fiber-Fed Visible Light Beam Combiner for the Navy Precision Optical Interferometer
    Visible-light long baseline interferometry holds the promise of advancing a number of important applications in fundamental astronomy, including the direct measurement of the angular diameters and oblateness of stars, and the direct measurement of the orbits of binary and multiple star systems. To advance, the field of visible-light interferometry requires development of instruments capable of combining more than just two or three beams at once. The Visible Imaging System for Interferometric Observations at NPOI (VISION) is a new visible light beam combiner for the Navy Precision Optical Interferometer (NPOI) that uses single-mode fibers to coherently combine light from up to six telescopes simultaneously with an image-plane combination scheme. It features a photometric camera for calibrations, and spatial filtering from single-mode fibers with two Andor Ixon electron multiplying CCDs. Here we present the VISION system, results of laboratory tests, and results of commissioning on-sky observations. We determine a new set of corrections to the power spectrum and bispectrum when using an electron-multipying CCD to measure visibility and closure phase, by taking into account non-Gaussian statistics and read noise, as required by our post-processing pipeline. We verify our post-processing pipeline via new on-sky observations of the O-type supergiant binary Zeta Orionis A, obtaining a flux ratio, position angle and separation in good agreement with expectations from the previously published orbit.

    160. 159 publications and 2581 citations in 2016.

159 publications and 2581 citations total.

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