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Research involving Lowell Observatory staff 2014
(Articles and chapters)

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Years: 2014 Bottom

    2014

  1. Elmegreen, B., Struck, C., Hunter, D., 2014, ApJ, 796, 110, Shrinking Galaxy Disks with Fountain-driven Accretion from the Halo
    Star formation in most galaxies requires cosmic gas accretion because the gas consumption time is short compared to the Hubble time. This accretion presumably comes from a combination of infalling satellite debris, cold flows, and condensation of hot halo gas at the cool disk interface, perhaps aided by a galactic fountain. In general, the accretion will have a different specific angular momentum than the part of the disk that receives it, even if the gas comes from the nearby halo. The gas disk then expands or shrinks over time. Here we show that condensation of halo gas at a rate proportional to the star formation rate in the fountain model will preserve an initial shape, such as an exponential, with a shrinking scale length, leaving behind a stellar disk with a slightly steeper profile of younger stars near the center. This process is slow for most galaxies, producing imperceptible radial speeds, and it may be dominated by other torques, but it could be important for blue compact dwarfs, which tend to have large, irregular gas reservoirs and steep blue profiles in their inner stellar disks.
  2. Gunther, H., Cody, A., Covey, K., Hillenbrand, L., Plavchan, P., Poppenhaeger, K., Rebull, L., Stauffer, J., Wolk, S., Allen, L., Bayo, A., Gutermuth, R., Hora, J., Meng, H., Morales-Calderon, M., Parks, J., Song, I., 2014, AJ, 148, 122, YSOVAR: Mid-infrared Variability in the Star-forming Region Lynds 1688
    The emission from young stellar objects (YSOs) in the mid-infrared (mid-IR) is dominated by the inner rim of their circumstellar disks. We present IR data from the Young Stellar Object VARiability (YSOVAR) survey of ~800 objects in the direction of the Lynds 1688 (L1688) star-forming region over four visibility windows spanning 1.6 yr using the Spitzer Space Telescope in its warm mission phase. Among all light curves, 57 sources are cluster members identified based on their spectral energy distribution and X-ray emission. Almost all cluster members show significant variability. The amplitude of the variability is larger in more embedded YSOs. Ten out of 57 cluster members have periodic variations in the light curves with periods typically between three and seven days, but even for those sources, significant variability in addition to the periodic signal can be seen. No period is stable over 1.6 yr. Nonperiodic light curves often still show a preferred timescale of variability that is longer for more embedded sources. About half of all sources exhibit redder colors in a fainter state. This is compatible with time-variable absorption toward the YSO. The other half becomes bluer when fainter. These colors can only be explained with significant changes in the structure of the inner disk. No relation between mid-IR variability and stellar effective temperature or X-ray spectrum is found.
  3. Ramakrishnan, V., Leon-Tavares, J., Rastorgueva-Foi, E., Wiik, K., Jorstad, S., Marscher, A., Tornikoski, M., Agudo, I., Lahteenmaki, A., Valtaoja, E., Aller, M., Blinov, D., Casadio, C., Efimova, N., Gurwell, M., Gomez, J., Hagen-Thorn, V., Joshi, M., Jarvela, E., Konstantinova, T., Kopatskaya, E., Larionov, V., Larionova, E., Larionova, L., Lavonen, N., MacDonald, N., McHardy, I., Molina, S., Morozova, D., Nieppola, E., Tammi, J., Taylor, B., Troitsky, I., 2014, MNRAS, 445, 1636, The connection between the parsec-scale radio jet and -ray flares in the blazar 1156+295
    The blazar 1156+295 was active at -ray energies, exhibiting three prominent flares during the year 2010. Here, we present results using the combination of broad-band (X-ray through mm single-dish) monitoring data and radio-band imaging data at 43 GHz on the connection of -ray events to the ejections of superluminal components and other changes in the jet of 1156+295. The kinematics of the jet over the interval 2007.0-2012.5 using 43 GHz Very Long Baseline Array observations reveal the presence of four moving and one stationary component in the inner region of the blazar jet. The propagation of the third and fourth components in the jet corresponds closely in time to the active phase of the source in -rays. We briefly discuss the implications of the structural changes in the jet for the mechanism of -ray production during bright flares. To localize the -ray emission site in the blazar, we performed the correlation analysis between the 43 GHz radio core and the -ray light curve. The time lag obtained from the correlation constrains the -ray emitting region in the parsec-scale jet.
  4. Holler, B., Young, L., Grundy, W., Olkin, C., Cook, J., 2014, Icar, 243, 104, Evidence for longitudinal variability of ethane ice on the surface of Pluto
    We present the results of an investigation using near-infrared spectra of Pluto taken on 72 separate nights using SpeX/IRTF. These data were obtained between 2001 and 2013 at various sub-observer longitudes. The aim of this work was to confirm the presence of ethane ice and to determine any longitudinal trends on the surface of Pluto. We computed models of the continuum near the 2.405 m band using Hapke theory and calculated an equivalent width of the ethane absorption feature for six evenly-spaced longitude bins and a grand average spectrum. The 2.405 m band on Pluto was detected at the 7.5- level from the grand average spectrum. Additionally, the band was found to vary longitudinally with the highest absorption occurring in the N2-rich region and the lowest absorption occurring in the visibly dark region. The longitudinal variability of 12CO does not match that of the 2.405 m band, suggesting a minimal contribution to the band by 13CO. We argue for ethane production in the atmosphere and present a theory of volatile transport to explain the observed longitudinal trend.
  5. Polishook, D., Moskovitz, N., DeMeo, F., Binzel, R., 2014, Icar, 243, 222, Rotationally resolved spectroscopy of asteroid pairs: No spectral variation suggests fission is followed by settling of dust
    The fission of an asteroid due to fast rotation can expose sub-surface material that was never previously exposed to any space weathering process. We examine the spectral properties of asteroid pairs that were disrupted in the last 2 million years to examine whether the site of the fission can be revealed. We studied the possibility that the sub-surface material, perhaps on one hemisphere, has spectral characteristics differing from the original weathered surface. This was achieved by performing rotationally-resolved spectroscopic observations to look for local variations as the asteroid rotates.

    We spectrally observed 11 asteroids in pairs in the near-IR and visible wavelength range. Photometric observations were also conducted to derive the asteroid lightcurves and to determine the rotational phases of the spectral observations. We do not detect any rotational spectral variations within the signal-to-noise of our measurements, which allows us to tightly constrain the extent of any existing surface heterogeneity.

    For each observed spectrum of a longitudinal segment of our measured asteroids, we estimate the maximal size of an un-detected ;spot; with a spectral signature different than the average. For five asteroids the maximal diameter of such a ;spot; is smaller by a factor of two than the diameter of the secondary member of the asteroid. Therefore, the site of the fission is larger than any area with a unique spectral parameters. This means the site of the fission does not have a unique spectrum. In the case of an ordinary chondrite asteroid (S-complex), where the site of fission is expected to present non-weathered spectra, a lack of a fission ;spot; (detectable spectroscopically) can be explained if the rotational-fission process is followed by the spread of dust that re-accumulates on the primary asteroid and covers it homogeneously. This is demonstrated for the young Asteroid 6070 that presents an Sq-type spectrum while its inner material, that is presumably revealed on the surface of its secondary member, 54827, has a non-weathered, Q-type spectrum. The spread of dust observed in the disintegration event of the Asteroid P/2013 R3, might be an example of such a process and an indication that P/2013 R3 was indeed formed in a rotational-fission event.

  6. Munari, U., Henden, A., Frigo, A., Zwitter, T., Bienayme, O., Bland-Hawthorn, J., Boeche, C., Freeman, K., Gibson, B., Gilmore, G., Grebel, E., Helmi, A., Kordopatis, G., Levine, S., Navarro, J., Parker, Q., Reid, W., Seabroke, G., Siebert, A., Siviero, A., Smith, T., Steinmetz, M., Templeton, M., Terrell, D., Welch, D., Williams, M., Wyse, R., 2014, AJ, 148, 81, APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings
    We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been 2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B - V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for EpolesB-V = 0.036 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| >= 25.
  7. Rebull, L., Cody, A., Covey, K., Gunther, H., Hillenbrand, L., Plavchan, P., Poppenhaeger, K., Stauffer, J., Wolk, S., Gutermuth, R., Morales-Calderon, M., Song, I., Barrado, D., Bayo, A., James, D., Hora, J., Vrba, F., Alves de Oliveira, C., Bouvier, J., Carey, S., Carpenter, J., Favata, F., Flaherty, K., Forbrich, J., Hernandez, J., McCaughrean, M., Megeath, S., Micela, G., Smith, H., Terebey, S., Turner, N., Allen, L., Ardila, D., Bouy, H., Guieu, S., 2014, AJ, 148, 92, Young Stellar Object VARiability (YSOVAR): Long Timescale Variations in the Mid-infrared
    The YSOVAR (Young Stellar Object VARiability) Spitzer Space Telescope observing program obtained the first extensive mid-infrared (3.6 and 4.5 m) time series photometry of the Orion Nebula Cluster plus smaller footprints in 11 other star-forming cores (AFGL 490, NGC 1333, Mon R2, GGD 12-15, NGC 2264, L1688, Serpens Main, Serpens South, IRAS 20050+2720, IC 1396A, and Ceph C). There are ~29,000 unique objects with light curves in either or both IRAC channels in the YSOVAR data set. We present the data collection and reduction for the Spitzer and ancillary data, and define the "standard sample" on which we calculate statistics, consisting of fast cadence data, with epochs roughly twice per day for ~40 days. We also define a "standard sample of members" consisting of all the IR-selected members and X-ray-selected members. We characterize the standard sample in terms of other properties, such as spectral energy distribution shape. We use three mechanisms to identify variables in the fast cadence datathe Stetson index, a 2 fit to a flat light curve, and significant periodicity. We also identified variables on the longest timescales possible of six to seven years by comparing measurements taken early in the Spitzer mission with the mean from our YSOVAR campaign. The fraction of members in each cluster that are variable on these longest timescales is a function of the ratio of Class I/total members in each cluster, such that clusters with a higher fraction of Class I objects also have a higher fraction of long-term variables. For objects with a YSOVAR-determined period and a [3.6]-[8] color, we find that a star with a longer period is more likely than those with shorter periods to have an IR excess. We do not find any evidence for variability that causes [3.6]-[4.5] excesses to appear or vanish within our data set; out of members and field objects combined, at most 0.02% may have transient IR excesses.
  8. Douglas, S., Agueros, M., Covey, K., Bowsher, E., Bochanski, J., Cargile, P., Kraus, A., Law, N., Lemonias, J., Arce, H., Fierroz, D., Kundert, A., 2014, ApJ, 795, 161, The Factory and the Beehive. II. Activity and Rotation in Praesepe and the Hyades
    Open clusters are collections of stars with a single, well-determined age, and can be used to investigate the connections between angular-momentum evolution and magnetic activity over a star's lifetime. We present the results of a comparative study of the relationship between stellar rotation and activity in two benchmark open clusters: Praesepe and the Hyades. As they have the same age and roughly solar metallicity, these clusters serve as an ideal laboratory for testing the agreement between theoretical and empirical rotation-activity relations at 600 Myr. We have compiled a sample of 720 spectramore than half of which are new observationsfor 516 high-confidence members of Praesepe; we have also obtained 139 new spectra for 130 high-confidence Hyads. We have also collected rotation periods (P rot) for 135 Praesepe members and 87 Hyads. To compare H emission, an indicator of chromospheric activity, as a function of color, mass, and Rossby number Ro , we first calculate an expanded set of values, with which we can obtain the H to bolometric luminosity ratio, L H/L bol, even when spectra are not flux-calibrated and/or stars lack reliable distances. Our values cover a broader range of stellar masses and colors (roughly equivalent to spectral types from K0 to M9), and exhibit better agreement between independent calculations, than existing values. Unlike previous authors, we find no difference between the two clusters in their H equivalent width or L H/L bol distributions, and therefore take the merged H and P rot data to be representative of 600 Myr old stars. Our analysis shows that H activity in these stars is saturated for {R_o} 0.11+0.02-0.03. Above that value activity declines as a power-law with slope =-0.73+0.16-0.12, before dropping off rapidly at Ro 0.4. These data provide a useful anchor for calibrating the age-activity-rotation relation beyond 600 Myr.
  9. Schaefer, G., Brummelaar, T., Gies, D., Farrington, C., Kloppenborg, B., Chesneau, O., Monnier, J., Ridgway, S., Scott, N., Tallon-Bosc, I., McAlister, H., Boyajian, T., Maestro, V., Mourard, D., Meilland, A., Nardetto, N., Stee, P., Sturmann, J., Vargas, N., Baron, F., Ireland, M., Baines, E., Che, X., Jones, J., Richardson, N., Roettenbacher, R., Sturmann, L., Turner, N., Tuthill, P., van Belle, G., von Braun, K., Zavala, R., Banerjee, D., Ashok, N., Joshi, V., Becker, J., Muirhead, P., 2014, Natur, 515, 234, The expanding fireball of Nova Delphini 2013
    A classical nova occurs when material accreting onto the surface of a white dwarf in a close binary system ignites in a thermonuclear runaway. Complex structures observed in the ejecta at late stages could result from interactions with the companion during the common-envelope phase. Alternatively, the explosion could be intrinsically bipolar, resulting from a localized ignition on the surface of the white dwarf or as a consequence of rotational distortion. Studying the structure of novae during the earliest phases is challenging because of the high spatial resolution needed to measure their small sizes. Here we report near-infrared interferometric measurements of the angular size of Nova Delphini 2013, starting one day after the explosion and continuing with extensive time coverage during the first 43 days. Changes in the apparent expansion rate can be explained by an explosion model consisting of an optically thick core surrounded by a diffuse envelope. The optical depth of the ejected material changes as it expands. We detect an ellipticity in the light distribution, suggesting a prolate or bipolar structure that develops as early as the second day. Combining the angular expansion rate with radial velocity measurements, we derive a geometric distance to the nova of 4.54 +/- 0.59 kiloparsecs from the Sun.
  10. Shkolnik, E., Rolph, K., Peacock, S., Barman, T., 2014, ApJL, 796, L20, Predicting Ly and Mg II Fluxes from K and M Dwarfs Using Galaxy Evolution Explorer Ultraviolet Photometry
    A star's ultraviolet (UV) emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Ly emission line at 1216 A, which dominates the far-ultraviolet (FUV) spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Ly, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Ly line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Ly and GALEX far- and near-ultraviolet (NUV) chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Ly to the GALEX fluxes reveal how the relative strength of Ly compared to the broadband fluxes weakens as the FUV and NUV excess flux increase. We also correlate GALEX fluxes with the strong NUV Mg II h+k spectral emission lines formed at lower chromospheric temperatures than Ly. The reported correlations provide estimates of intrinsic Ly and Mg II fluxes for the thousands of K and M stars in the archived GALEX all-sky surveys. These will constrain new stellar upper atmosphere models for cool stars and provide realistic inputs to models describing exoplanetary photochemistry and atmospheric evolution in the absence of UV spectroscopy.

    Based on observations made with the NASA Galaxy Evolution Explorer (GALEX). GALEX was operated for NASA by the California Institute of Technology under NASA contract NAS5-98034.

  11. Cottaar, M., Covey, K., Meyer, M., Nidever, D., Stassun, K., Foster, J., Tan, J., Chojnowski, S., da Rio, N., Flaherty, K., Frinchaboy, P., Skrutskie, M., Majewski, S., Wilson, J., Zasowski, G., 2014, ApJ, 794, 125, IN-SYNC I: Homogeneous Stellar Parameters from High-resolution APOGEE Spectra for Thousands of Pre-main Sequence Stars
    Over two years, 8859 high-resolution H-band spectra of 3493 young (1-10 Myr) stars were gathered by the multi-object spectrograph of the APOGEE project as part of the IN-SYNC ancillary program of the SDSS-III survey. Here we present the forward modeling approach used to derive effective temperatures, surface gravities, radial velocities, rotational velocities, and H-band veiling from these near-infrared spectra. We discuss in detail the statistical and systematic uncertainties in these stellar parameters. In addition, we present accurate extinctions by measuring the E(J - H) of these young stars with respect to the single-star photometric locus in the Pleiades. Finally, we identify an intrinsic stellar radius spread of about 25% for late-type stars in IC 348 using three (nearly) independent measures of stellar radius, namely, the extinction-corrected J-band magnitude, the surface gravity, and the Rsin i from the rotational velocities and literature rotation periods. We exclude that this spread is caused by uncertainties in the stellar parameters by showing that the three estimators of stellar radius are correlated, so that brighter stars tend to have lower surface gravities and larger Rsin i than fainter stars at the same effective temperature. Tables providing the spectral and photometric parameters for the Pleiades and IC 348 have been provided online.
  12. Shkolnik, E., Barman, T., 2014, AJ, 148, 64, HAZMAT. I. The Evolution of Far-UV and Near-UV Emission from Early M Stars
    The spectral energy distribution, variability, and evolution of the high-energy radiation from an M dwarf planet host is crucial in understanding the planet's atmospheric evolution and habitability and in interpreting the planet's spectrum. The star's extreme-UV (EUV), far-UV (FUV), and near-UV (NUV) emission can chemically modify, ionize, and erode the atmosphere over time. This makes determining the lifetime exposure of such planets to stellar UV radiation critical for both the evolution of a planet's atmosphere and our potential to characterize it. Using the early M star members of nearby young moving groups, which sample critical ages in planet formation and evolution, we measure the evolution of the GALEX NUV and FUV flux as a function of age. The median UV flux remains at a "saturated" level for a few hundred million years, analogous to that observed for X-ray emission. By the age of the Hyades Cluster (650 Myr), we measure a drop in UV flux by a factor of 2-3 followed by a steep drop from old (several Gyrs) field stars. This decline in activity beyond 300 Myr follows roughly t -1. Despite this clear evolution, there remains a wide range, of 1-2 orders of magnitude, in observed emission levels at every age. These UV data supply the much-needed constraints to M dwarf upper-atmosphere models, which will provide empirically motivated EUV predictions and more accurate age-dependent UV spectra as inputs to planetary photochemical models.

    Based on observations made with the NASA Galaxy Evolution Explorer (GALEX). GALEX was operated for NASA by the California Institute of Technology under NASA contract NAS5-98034.

  13. Rapson, V., Pipher, J., Gutermuth, R., Megeath, S., Allen, T., Myers, P., Allen, L., 2014, ApJ, 794, 124, A Spitzer View of the Giant Molecular Cloud MON OB1 EAST/NGC 2264
    We present Spitzer 3.6, 4.5, 5.8, 8.0, and 24 m images of the Mon OB1 East giant molecular cloud, which contains the young star forming region NGC 2264, as well as more extended star formation. With Spitzer data and Two Micron All Sky Survey photometry, we identify and classify young stellar objects (YSOs) with dusty circumstellar disks and/or envelopes in Mon OB1 East by their infrared-excess emission and study their distribution with respect to cloud material. We find a correlation between the local surface density of YSOs and column density of molecular gas as traced by dust extinction that is roughly described as a power law in these quantities. NGC 2264 follows a power-law index of ~2.7, exhibiting a large YSO surface density for a given gas column density. Outside of NGC 2264 where the surface density of YSOs is lower, the power law is shallower and the region exhibits a larger gas column density for a YSO surface density, suggesting the star formation is more recent. In order to measure the fraction of cloud members with circumstellar disks/envelopes, we estimate the number of diskless pre-main-sequence stars by statistical removal of background star detections. We find that the disk fraction of the NGC 2264 region is 45%, while the surrounding, more distributed regions show a disk fraction of 19%. This may be explained by the presence of an older, more dispersed population of stars. In total, the Spitzer observations provide evidence for heterogenous, non-coeval star formation throughout the Mon OB1 cloud.
  14. Ishiguro, M., Kuroda, D., Hasegawa, S., Kim, M., Choi, Y., Moskovitz, N., Abe, S., Pan, K., Takahashi, J., Takagi, Y., Arai, A., Tokimasa, N., Hsieh, H., Thomas-Osip, J., Osip, D., Abe, M., Yoshikawa, M., Urakawa, S., Hanayama, H., Sekiguchi, T., Wada, K., Sumi, T., Tristram, P., Furusawa, K., Abe, F., Fukui, A., Nagayama, T., Warjurkar, D., Rau, A., Greiner, J., Schady, P., Knust, F., Usui, F., Muller, T., 2014, ApJ, 792, 74, Optical Properties of (162173) 1999 JU3: In Preparation for the JAXA Hayabusa 2 Sample Return Mission
    We investigated the magnitude-phase relation of (162173) 1999 JU3, a target asteroid for the JAXA Hayabusa 2 sample return mission. We initially employed the International Astronomical Union's H-G formalism but found that it fits less well using a single set of parameters. To improve the inadequate fit, we employed two photometric functions: the Shevchenko and Hapke functions. With the Shevchenko function, we found that the magnitude-phase relation exhibits linear behavior in a wide phase angle range ( = 5-75) and shows weak nonlinear opposition brightening at < 5, providing a more reliable absolute magnitude of H V = 19.25 0.03. The phase slope (0.039 0.001 mag deg-1) and opposition effect amplitude (parameterized by the ratio of intensity at = 0.3 to that at = 5, I(0.3)/I(5) = 1.31 0.05) are consistent with those of typical C-type asteroids. We also attempted to determine the parameters for the Hapke model, which are applicable for constructing the surface reflectance map with the Hayabusa 2 onboard cameras. Although we could not constrain the full set of Hapke parameters, we obtained possible values, w = 0.041, g = -0.38, B 0 = 1.43, and h = 0.050, assuming a surface roughness parameter \bar{ } = 20. By combining our photometric study with a thermal model of the asteroid, we obtained a geometric albedo of p v = 0.047 0.003, phase integral q = 0.32 0.03, and Bond albedo A B = 0.014 0.002, which are commensurate with the values for common C-type asteroids.

    This work was conducted as part of the activities of the JAXA Hayabusa 2 Ground-Based Observation Sub-Group.

  15. Lopez, B., Lagarde, S., Jaffe, W., Petrov, R., Scholler, M., Antonelli, P., Beckmann, U., Berio, P., Bettonvil, F., Glindemann, A., Gonzalez, J., Graser, U., Hofmann, K., Millour, F., Robbe-Dubois, S., Venema, L., Wolf, S., Henning, T., Lanz, T., Weigelt, G., Agocs, T., Bailet, C., Bresson, Y., Bristow, P., Dugue, M., Heininger, M., Kroes, G., Laun, W., Lehmitz, M., Neumann, U., Augereau, J., Avila, G., Behrend, J., van Belle, G., Berger, J., van Boekel, R., Bonhomme, S., Bourget, P., Brast, R., Clausse, J., Connot, C., Conzelmann, R., Cruzalebes, P., Csepany, G., Danchi, W., Delbo, M., Delplancke, F., Dominik, C., van Duin, A., Elswijk, E., Fantei, Y., Finger, G., Gabasch, A., Gay, J., Girard, P., Girault, V., Gitton, P., Glazenborg, A., Gonte, F., Guitton, F., Guniat, S., De Haan, M., Haguenauer, P., Hanenburg, H., Hogerheijde, M., ter Horst, R., Hron, J., Hugues, Y., Hummel, C., Idserda, J., Ives, D., Jakob, G., Jasko, A., Jolley, P., Kiraly, S., Kohler, R., Kragt, J., Kroener, T., Kuindersma, S., Labadie, L., Leinert, C., Le Poole, R., Lizon, J., Lucuix, C., Marcotto, A., Martinache, F., Martinot-Lagarde, G., Mathar, R., Matter, A., Mauclert, N., Mehrgan, L., Meilland, A., Meisenheimer, K., Meisner, J., Mellein, M., Menardi, S., Menut, J., Merand, A., Morel, S., Mosoni, L., Navarro, R., Nussbaum, E., Ottogalli, S., Palsa, R., Panduro, J., Pantin, E., Parra, T., Percheron, I., Duc, T., Pott, J., Pozna, E., Przygodda, F., Rabbia, Y., Richichi, A., Rigal, F., Roelfsema, R., Rupprecht, G., Schertl, D., Schmidt, C., Schuhler, N., Schuil, M., Spang, A., Stegmeier, J., Thiam, L., Tromp, N., Vakili, F., Vannier, M., Wagner, K., Woillez, J., 2014, Msngr, 157, 5, An Overview of the MATISSE Instrument Science, Concept and Current Status
    MATISSE, a second generation Very Large Telescope Interferometer (VLTI) instrument, is a combined imager and spectrograph for interferometry in the 3-5 m region (L- and M-bands) and the 8-13 m window (N-band). MATISSE builds on the experience gained with the VLTI's first generation instruments. It employs multi-axial beam combination while also providing wavelength differential visibility and phase, and closure-phase aperture-synthesis imaging at a range of spectral resolutions. MATISSE is designed for a broad range of science goals, and its potential for studies of the discs around young stars and active galactic nuclei are highlighted. The instrument concept and operating modes are described; construction is in progress towards installation at the VLTI in 2016.
  16. Adams, E., Gulbis, A., Elliot, J., Benecchi, S., Buie, M., Trilling, D., Wasserman, L., 2014, AJ, 148, 55, De-biased Populations of Kuiper Belt Objects from the Deep Ecliptic Survey
    The Deep Ecliptic Survey (DES) was a survey project that discovered hundreds of Kuiper Belt objects from 1998 to 2005. Extensive follow-up observations of these bodies has yielded 304 objects with well-determined orbits and dynamical classifications into one of several categories: Classical, Scattered, Centaur, or 16 mean-motion resonances with Neptune. The DES search fields are well documented, enabling us to calculate the probability on each frame of detecting an object with its particular orbital parameters and absolute magnitude at a randomized point in its orbit. The detection probabilities range from a maximum of 0.32 for the 3:2 resonant object 2002 GF 32 to a minimum of 1.5 10-7 for the faint Scattered object 2001 FU 185. By grouping individual objects together by dynamical classes, we can estimate the distributions of four parameters that define each class: semimajor axis, eccentricity, inclination, and object size. The orbital element distributions (a, e, and i) were fit to the largest three classes (Classical, 3:2, and Scattered) using a maximum likelihood fit. Using the absolute magnitude (H magnitude) as a proxy for the object size, we fit a power law to the number of objects versus H magnitude for eight classes with at least five detected members (246 objects). The Classical objects are best fit with a power-law slope of = 1.02 0.01 (observed from 5 <= H <= 7.2). Six other dynamical classes (Scattered plus five resonances) have consistent magnitude distribution slopes with the Classicals, provided that the absolute number of objects is scaled. Scattered objects are somewhat more numerous than Classical objects, while there are only a quarter as many 3:2 objects as Classicals. The exception to the power law relation is the Centaurs, which are non-resonant objects with perihelia closer than Neptune and therefore brighter and detectable at smaller sizes. Centaurs were observed from 7.5 < H < 11, and that population is best fit by a power law with = 0.42 0.02. This is consistent with a knee in the H-distribution around H = 7.2 as reported elsewhere. Based on the Classical-derived magnitude distribution, the total number of objects (H <= 7) in each class is: Classical (2100 300 objects), Scattered (2800 400), 3:2 (570 80), 2:1 (400 50), 5:2 (270 40), 7:4 (69 9), 5:3 (60 8). The independent estimate for the number of Centaurs in the same H range is 13 5. If instead all objects are divided by inclination into "Hot" and "Cold" populations, following Fraser et al., we find that Hot = 0.90 0.02, while Cold = 1.32 0.02, in good agreement with that work.
  17. Garcia, E., Stassun, K., Pavlovski, K., Hensberge, H., Gomez Maqueo Chew, Y., Claret, A., 2014, AJ, 148, 39, A Strict Test of Stellar Evolution Models: The Absolute Dimensions of the Massive Benchmark Eclipsing Binary V578 Mon
    We determine the absolute dimensions of the eclipsing binary V578 Mon, a detached system of two early B-type stars (B0V + B1V, P = 2.40848 days) in the star-forming region NGC 2244 of the Rosette Nebula. From the light curve analysis of 40 yr of photometry and the analysis of HERMES spectra, we find radii of 5.41 0.04 R and 4.29 0.05 R, and temperatures of 30,000 500 K and 25,750 435 K, respectively. We find that our disentangled component spectra for V578 Mon agree well with previous spectral disentangling from the literature. We also reconfirm the previous spectroscopic orbit of V578 Mon finding that masses of 14.54 0.08 M and 10.29 0.06 M are fully compatible with the new analysis. We compare the absolute dimensions to the rotating models of the Geneva and Utrecht groups and the models of the Granada group. We find that all three sets of models marginally reproduce the absolute dimensions of both stars with a common age within the uncertainty for gravity-effective temperature isochrones. However, there are some apparent age discrepancies for the corresponding mass-radius isochrones. Models with larger convective overshoot, >0.35, worked best. Combined with our previously determined apsidal motion of 0.07089^{+0.00021}_{-0.00013} deg cycle-1, we compute the internal structure constants (tidal Love number) for the Newtonian and general relativistic contribution to the apsidal motion as log k 2 = -1.975 0.017 and log k 2 = -3.412 0.018, respectively. We find the relativistic contribution to the apsidal motion to be small, <4%. We find that the prediction of log k 2, theo = -2.005 0.025 of the Granada models fully agrees with our observed log k 2.
  18. Lanza, A., Shkolnik, E., 2014, MNRAS, 443, 1451, Secular orbital evolution of planetary systems and the dearth of close-in planets around fast rotators
    Recent analyses of Kepler space telescope data reveal that transiting planets with orbital periods shorter than 2-3 d are generally observed around late-type stars with rotation periods longer than 5-10 d. We investigate different explanations for this phenomenon and favour an interpretation based on secular perturbations in multiplanet systems on non-resonant orbits. In those systems, the orbital eccentricity of the innermost planet can reach values close to unity through a process of chaotic diffusion of its orbital elements in the phase space. When the eccentricity of the innermost orbit becomes so high that the periastron gets closer than 0.05 au, tides shrink and circularize the orbit producing a close-in planet on a time-scale 50 Myr. The probability of high eccentricity excitation and subsequent circularization is estimated and is found to increase with the age of the system. Thus, we are able to explain the observed statistical correlation between stellar rotation and minimum orbital period of the innermost planet by using the stellar rotation period as a proxy of its age through gyrochronology. Moreover, our model is consistent with the entire observed distributions of the rotation and orbital periods Porb for 3 Porb 15 d.
  19. Biddle, L., Pearson, K., Crossfield, I., Fulton, B., Ciceri, S., Eastman, J., Barman, T., Mann, A., Henry, G., Howard, A., Williamson, M., Sinukoff, E., Dragomir, D., Vican, L., Mancini, L., Southworth, J., Greenberg, A., Turner, J., Thompson, R., Taylor, B., Levine, S., Webber, M., 2014, MNRAS, 443, 1810, Warm ice giant GJ 3470b - II. Revised planetary and stellar parameters from optical to near-infrared transit photometry
    It is important to explore the diversity of characteristics of low-mass, low-density planets to understand the nature and evolution of this class of planets. We present a homogeneous analysis of 12 new and 9 previously published broad-band photometric observations of the Uranus-sized extrasolar planet GJ 3470b, which belongs to the growing sample of sub-Jovian bodies orbiting M dwarfs. The consistency of our analysis explains some of the discrepancies between previously published results and provides updated constraints on the planetary parameters. Our data are also consistent with previous transit observations of this system. The physical properties of the transiting system can only be constrained as well as the host star is characterized, so we provide new spectroscopic measurements of GJ 3470 from 0.33 to 2.42 m to aid our analysis. We find R* = 0.48 0.04 R, M* = 0.51 0.06 M, and Teff = 3652 50K for GJ 3470, along with a rotation period of 20.70 0.15 d and an R-band amplitude of 0.01 mag, which is small enough that current transit measurements should not be strongly affected by stellar variability. However, to report definitively whether stellar activity has a significant effect on the light curves, this requires future multiwavelength, multi-epoch studies of GJ 3470. We also present the most precise orbital ephemeris for this system: To = 2455983.70472 0.00021BJDTDB, P = 3.336 6487^{+0.000 0043}_{-0.000 0033} d, and we see no evidence for transit timing variations greater than 1 min. Our reported planet to star radius ratio is 0.076 42 0.000 37. The physical parameters of this planet are Rp = 3.88 0.32 R and Mp = 13.73 1.61 M. Because of our revised stellar parameters, the planetary radius we present is smaller than previously reported values. We also perform a second analysis of the transmission spectrum of the entire ensemble of transit observations to date, supporting the existence of an H2-dominated atmosphere exhibiting a strong Rayleigh scattering slope.
  20. Levesque, E., Massey, P., Zytkow, A., Morrell, N., 2014, MNRAS, 443, L94, Discovery of a Thorne-Zytkow object candidate in the Small Magellanic Cloud.
    Thorne-Zytkow objects (TZOs) are a theoretical class of star in which a compact neutron star is surrounded by a large, diffuse envelope. Supergiant TZOs are predicted to be almost identical in appearance to red supergiants (RSGs). The best features that can be used at present to distinguish TZOs from the general RSG population are the unusually strong heavy-element and Li lines present in their spectra, products of the star's fully convective envelope linking the photosphere with the extraordinarily hot burning region in the vicinity of the neutron star core. Here, we present our discovery of a TZO candidate in the Small Magellanic Cloud. It is the first star to display the distinctive chemical profile of anomalous element enhancements thought to be unique to TZOs. The positive detection of a TZO will provide the first direct evidence for a completely new model of stellar interiors, a theoretically predicted fate for massive binary systems, and never-seen-before nucleosynthesis processes that would offer a new channel for Li and heavy-element production in our Universe.
  21. Ricker, G., Winn, J., Vanderspek, R., Latham, D., Bakos, G., Bean, J., Berta-Thompson, Z., Brown, T., Buchhave, L., Butler, N., Butler, R., Chaplin, W., Charbonneau, D., Christensen-Dalsgaard, J., Clampin, M., Deming, D., Doty, J., De Lee, N., Dressing, C., Dunham, E., Endl, M., Fressin, F., Ge, J., Henning, T., Holman, M., Howard, A., Ida, S., Jenkins, J., Jernigan, G., Johnson, J., Kaltenegger, L., Kawai, N., Kjeldsen, H., Laughlin, G., Levine, A., Lin, D., Lissauer, J., MacQueen, P., Marcy, G., McCullough, P., Morton, T., Narita, N., Paegert, M., Palle, E., Pepe, F., Pepper, J., Quirrenbach, A., Rinehart, S., Sasselov, D., Sato, B., Seager, S., Sozzetti, A., Stassun, K., Sullivan, P., Szentgyorgyi, A., Torres, G., Udry, S., Villasenor, J., 2014, SPIE, 9143, 914320, Transiting Exoplanet Survey Satellite (TESS)
    The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with IC (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations.
  22. Biller, B., Liu, M., Wahhaj, Z., Nielsen, E., Hayward, T., Chun, M., Close, L., Ftaclas, C., Males, J., Hartung, M., Reid, I., Shkolnik, E., Skemer, A., Tecza, M., Thatte, N., Clarke, F., Toomey, D., 2014, SPIE, 9148, 91481O, Results from the Gemini NICI Planet-Finding Campaign
    From 2008 December to 2012 September, the NICI (Near-Infrared Coronagraphic Imager at the Gemini-South 8.1-m) Planet-Finding Campaign (Liu et al. 2010) obtained deep, high-contrast AO imaging of a carefully selected sample of over 200 young, nearby stars. In the course of the campaign, we discovered four co-moving brown dwarf companions: PZ Tel B (36+/-6 MJup, 16.4+/-1.0 AU), CD-35 2722B (31+/-8 MJup, 67+/-4 AU), HD 1160B (33+12 -9 MJup, 81+/- AU), and HIP 79797Bb (55+20-19MJup, 3 AU from the previously known brown dwarf companion HIP 79797Ba), as well as numerous stellar binaries. Three survey papers have been published to date, covering: 1) high mass stars (Nielsen et al. 2013), 2) debris disk stars (Wahhaj et al. 2013), and 3) stars which are members of nearby young moving groups (Biller et al. 2013). In addition, the Campaign has yielded new orbital constraints for the ~8-10 MJup planet Pic (Nielsen et al. 2014) and a high precision measurement of the star-disk offset for the well-known disk around HR 4796A (Wahhaj et al. 2014). Here we discuss constraints placed on the distribution of wide giant exoplanets from the NICI Campaign, new substellar companion discoveries, and characterization both of exoplanets and circumstellar disks.
  23. Boyajian, T., von Braun, K., van Belle, G., McAlister, H., ten Brummelaar, T., Kane, S., Muirhead, P., Jones, J., White, R., Schaefer, G., Ciardi, D., Henry, T., Lopez-Morales, M., Ridgway, S., Gies, D., Jao, W., Rojas-Ayala, B., Parks, J., Sturmann, L., Sturmann, J., Turner, N., Farrington, C., Goldfinger, P., Berger, D., 2014, ApJ, 790, 166, Erratum: "Stellar Diameters and Temperatures. II. Main-sequence K- and M-stars" (2012, ApJ, 757, 112)
    No abstract found.
  24. Neugent, K., Massey, P., 2014, ApJ, 789, 10, The Close Binary Frequency of Wolf-Rayet Stars as a Function of Metallicity in M31 and M33
    Massive star evolutionary models generally predict the correct ratio of WC-type and WN-type Wolf-Rayet stars at low metallicities, but underestimate the ratio at higher (solar and above) metallicities. One possible explanation for this failure is perhaps single-star models are not sufficient and Roche-lobe overflow in close binaries is necessary to produce the "extra" WC stars at higher metallicities. However, this would require the frequency of close massive binaries to be metallicity dependent. Here we test this hypothesis by searching for close Wolf-Rayet binaries in the high metallicity environments of M31 and the center of M33 as well as in the lower metallicity environments of the middle and outer regions of M33. After identifying ~100 Wolf-Rayet binaries based on radial velocity variations, we conclude that the close binary frequency of Wolf-Rayets is not metallicity dependent and thus other factors must be responsible for the overabundance of WC stars at high metallicities. However, our initial identifications and observations of these close binaries have already been put to good use as we are currently observing additional epochs for eventual orbit and mass determinations.

    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.

  25. Williamson, K., Jorstad, S., Marscher, A., Larionov, V., Smith, P., Agudo, I., Arkharov, A., Blinov, D., Casadio, C., Efimova, N., Gomez, J., Hagen-Thorn, V., Joshi, M., Konstantinova, T., Kopatskaya, E., Larionova, E., Larionova, L., Malmrose, M., McHardy, I., Molina, S., Morozova, D., Schmidt, G., Taylor, B., Troitsky, I., 2014, ApJ, 789, 135, Comprehensive Monitoring of Gamma-Ray Bright Blazars. I. Statistical Study of Optical, X-Ray, and Gamma-Ray Spectral Slopes
    We present -ray, X-ray, ultraviolet, optical, and near-infrared light curves of 33 -ray bright blazars over 4 years that we have been monitoring since 2008 August with multiple optical, ground-based telescopes and the Swift satellite, and augmented by data from the Fermi Gamma-ray Space Telescope and other publicly available data from Swift. The sample consists of 21 flat-spectrum radio quasars (FSRQs) and 12 BL Lac objects (BL Lacs). We identify quiescent and active states of the sources based on their -ray behavior. We derive -ray, X-ray, and optical spectral indices, , X , and o , respectively (F vprop), and construct spectral energy distributions during quiescent and active states. We analyze the relationships between different spectral indices, blazar classes, and activity states. We find (1) significantly steeper -ray spectra of FSRQs than for BL Lacs during quiescent states, but a flattening of the spectra for FSRQs during active states while the BL Lacs show no significant change; (2) a small difference of X within each class between states, with BL Lac X-ray spectra significantly steeper than in FSRQs; (3) a highly peaked distribution of X-ray spectral slopes of FSRQs at ~ -0.60, but a very broad distribution of X of BL Lacs during active states; (4) flattening of the optical spectra of FSRQs during quiescent states, but no statistically significant change of o of BL Lacs between states; and (5) a positive correlation between optical and -ray spectral slopes of BL Lacs, with similar values of the slopes. We discuss the findings with respect to the relative prominence of different components of high-energy and optical emission as the flux state changes.
  26. Morrell, N., Massey, P., Neugent, K., Penny, L., Gies, D., 2014, ApJ, 789, 139, Photometric and Spectroscopic Studies of Massive Binaries in the Large Magellanic Cloud. II. Three O-type Systems in the 30 Dor Region
    This is the second paper in a series devoted to the study of massive binary systems in the Large Magellanic Cloud (LMC). We mainly aim to provide accurate data that constrains the mass-luminosity relation for the most massive stars but also to address the long lasting problem known as the "mass discrepancy." We present here our results for three binaries (LMC 169782, LMC 171520, and [P93] 921) harboring the earliest O-type componentsranging from O4 V to O6.5 Vamong our sample of 17 systems. Our photometry provided accurate periods for the studied systems, allowing the spectroscopic observations to be performed at selected phases where the radial velocity separation between binary components is larger. Following the procedure outlined in our first paper of this series, after solving the radial velocity curves for orbital parameters, we used tomographic reconstruction to obtain the individual spectra of each star, from which we determined effective temperatures via a model atmosphere fitting with FASTWIND. This information, combined with the light-curve analysis that was performed with GENSYN, enabled the determination of absolute masses, radii, and bolometric luminosities that are compared with those predicted by modern stellar evolutionary models finding that they agree within the uncertainties. Nevertheless, the comparison seems to confirm the small differences found in the first paper of this series in the sense that the evolutionary masses are slightly larger than the Keplerian ones, with differences averaging ~10%, or alternatively, the stellar evolutionary models predict luminosities that are somewhat lower than observed. Still, the overall agreement between the current evolutionary models and the empirically determined stellar parameters is remarkable.

    This paper includes data gathered with the 6.5 m Magellan and 1.0 m Swope Telescopes located at Las Campanas Observatory, Chile, as well as data obtained with the SMARTS Consortium 1.3 and 1.0 m Telescopes located at Cerro Tololo Inter-American Observatory, Chile.

  27. Jorgensen, A., Mozurkewich, D., Schmitt, H., van Belle, G., Hutter, D., Clark, J., Armstrong, J., Baines, E., Newman, K., Landavazo, M., Sun, B., Restaino, S., 2014, SPIE, 9146, 91460A, Progress toward unprecedented imaging of stellar surfaces with the Navy precision optical interferometer
    We present progress on the stellar surface imaging project recently funded by the U. S. National Science Foun- dation. With the unique layout of the Navy Precision Optical Interferometer (NPOI) in combination with data acquisition and fringe-tracking upgrades we expect to be able to substantially exceed the imaging fidelity and resolution of any other interferometer in operation. The project combines several existing advances and infras- tructure at NPOI with modest enhancements. For optimal imaging there are several requirements that should be fulfilled. The observatory should be capable of measuring visibilities on a wide range of baseline lengths and orientations, providing complete Fourier (UV) coverage in a short period of time. It should measure visibility amplitudes with good SNR on all baselines as critical imaging information is often contained in low-amplitude visibilities. It should measure the visibility phase on all baselines. The technologies which can achieve this are the NPOI Y-shaped array with (nearly) equal spacing between telescopes and an ability for rapid configuration. Placing 6-telescopes in a row makes it possible to measure visibilities into the 4th lobe of the visibility function. By arranging the 12 available telescopes carefully we can switch, every few days, between 6 different 6-station chains which provide symmetric coverage in the Fourier plane without moving any telescopes, only by moving beam relay mirrors. The 6-station chains are important to achieve the highest imaging resolution, and switching rapidly between station chains provides uniform coverage. Coherent integration techniques can be used to obtain good SNR on very small visibilities. Coherently integrated visibilities can be used for imaging with standard radio imaging packages such as AIPS. The commissioning of one additional station, the use of new data acqui- sition hardware and fringe tracking algorithms are the enhancements which are making this project a reality. The New Classic data acquisition system, based on a powerful Stratix FPGA and fast Direct Memory Access module, upgrades the existing Classic beam combiner to allow for continuous data recording across all baselines available with 6 telescopes. It also provides the computing power and software environment necessary for im- plementing the 6-station, 5-baseline fringe-tracking algorithms. In separate papers we discuss the New Classic data acquisition system and the fringe-tracking algorithms in greater detail. In this paper we will focus on an overview of the project. We will describe the observation planning, logistics of the observations, and discuss the current status of the project including preliminary results and simulations of expected future results.
  28. Lopez, B., Lagarde, S., Jaffe, W., Petrov, R., Scholler, M., Antonelli, P., Beckman, U., Berio, P., Bettonvil, F., Graser, U., Millour, F., Robbe-Dubois, S., Venema, L., Wolf, S., Bristow, P., Glindemann, A., Gonzalez, J., Lanz, T., Henning, T., Weigelt, G., Agocs, T., Augereau, J., Avila, G., Bailet, C., Behrend, J., Berger, J., von Boekel, R., Bonhomme, S., Bourget, P., Brast, R., Bresson, Y., Clausse, J., Chesneau, O., Csepany, G., Connot, C., Crida, A., Danchi, W., Delbo, M., Delplancke, F., Dominik, C., Dugue, M., Elswijk, E., Fantei, Y., Finger, G., Gabasch, A., Girard, P., Girault, V., Gitton, P., Glazenborg, A., Gonte, F., Guitton, F., Guniat, S., De Haan, M., Haguenauer, P., Hanenburg, H., Heininger, M., Hofmann, K., Hogerheijde, M., ter Horst, R., Hron, J., Hughes, Y., Ives, D., Jakob, G., Jasko, A., Jolley, P., Kragt, J., Kohler, R., Kroener, T., Kroes, G., Labadie, L., Laun, W., Lehmitz, M., Leinert, C., Lizon, J., Lucuix, C., Marcotto, A., Martinache, F., Matter, A., Martinot-Lagarde, G., Mauclert, N., Mehrgan, L., Meilland, A., Mellein, M., Menardi, S., Menut, J., Meisenheimer, K., Morel, S., Mosoni, L., Navarro, R., Neumann, U., Nussbaum, E., Ottogalli, S., Palsa, R., Panduro, J., Pantin, E., Percheron, I., Duc, T., Pott, J., Pozna, E., Przygodda, F., Richichi, A., Rigal, F., Rupprecht, G., Schertl, D., Stegmeier, J., Thiam, L., Tromp, N., Vannier, M., Vakili, F., van Belle, G., Wagner, K., Woillez, J., 2014, SPIE, 9146, 91460M, MATISSE status report and science forecast
    MATISSE is the mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This second generation interferometry instrument will open new avenues in the exploration of our Universe. Mid-infrared interferometry with MATISSE will allow significant advances in various fundamental research fields: studies of disks around young stellar objects where planets form and evolve, surface structures and mass loss of stars in late evolutionary stages, and the environments of black holes in active galactic nuclei. MATISSE is a unique instrument. As a first breakthrough it will enlarge the spectral domain used by optical interferometry by offering the L & M bands in addition to the N band, opening a wide wavelength domain, ranging from 2.8 to 13 m on angular scales of 3 mas (L/M band) / 10 mas (N band). As a second breakthrough, it will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. MATISSE will offer various ranges of spectral resolution between R~30 to ~5000. In this article, we present some of the main science objectives that have driven the instrument design. We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performance and discuss the project status. The operations concept will be detailed in a more specific future article, illustrating the observing templates operating the instrument, the data reduction and analysis, and the image reconstruction software.
  29. Monnier, J., Kraus, S., Buscher, D., Berger, J., Haniff, C., Ireland, M., Labadie, L., Lacour, S., Le Coroller, H., Petrov, R., Pott, J., Ridgway, S., Surdej, J., ten Brummelaar, T., Tuthill, P., van Belle, G., 2014, SPIE, 9146, 914610, Planet formation imager (PFI): introduction and technical considerations
    Complex non-linear and dynamic processes lie at the heart of the planet formation process. Through numerical simulation and basic observational constraints, the basics of planet formation are now coming into focus. High resolution imaging at a range of wavelengths will give us a glimpse into the past of our own solar system and enable a robust theoretical framework for predicting planetary system architectures around a range of stars surrounded by disks with a diversity of initial conditions. Only long-baseline interferometry can provide the needed angular resolution and wavelength coverage to reach these goals and from here we launch our planning efforts. The aim of the Planet Formation Imager" (PFI) project is to develop the roadmap for the construction of a new near-/mid-infrared interferometric facility that will be optimized to unmask all the major stages of planet formation, from initial dust coagulation, gap formation, evolution of transition disks, mass accretion onto planetary embryos, and eventual disk dispersal. PFI will be able to detect the emission of the cooling, newlyformed planets themselves over the first 100 Myrs, opening up both spectral investigations and also providing a vibrant look into the early dynamical histories of planetary architectures. Here we introduce the Planet Formation Imager (PFI) Project (www.planetformationimager.org) and give initial thoughts on possible facility architectures and technical advances that will be needed to meet the challenging top-level science requirements.
  30. Kraus, S., Monnier, J., Harries, T., Dong, R., Bate, M., Whitney, B., Zhu, Z., Buscher, D., Berger, J., Haniff, C., Ireland, M., Labadie, L., Lacour, S., Petrov, R., Ridgway, S., Surdej, J., ten Brummelaar, T., Tuthill, P., van Belle, G., 2014, SPIE, 9146, 914611, The science case for the Planet Formation Imager (PFI)
    Among the most fascinating and hotly-debated areas in contemporary astrophysics are the means by which planetary systems are assembled from the large rotating disks of gas and dust which attend a stellar birth. Although important work has already been, and is still being done both in theory and observation, a full understanding of the physics of planet formation can only be achieved by opening observational windows able to directly witness the process in action. The key requirement is then to probe planet-forming systems at the natural spatial scales over which material is being assembled. By definition, this is the so-called Hill Sphere which delineates the region of influence of a gravitating body within its surrounding environment. The Planet Formation Imager project (PFI; http://www.planetformationimager.org) has crystallized around this challenging goal: to deliver resolved images of Hill-Sphere-sized structures within candidate planethosting disks in the nearest star-forming regions. In this contribution we outline the primary science case of PFI. For this purpose, we briefly review our knowledge about the planet-formation process and discuss recent observational results that have been obtained on the class of transition disks. Spectro-photometric and multi-wavelength interferometric studies of these systems revealed the presence of extended gaps and complex density inhomogeneities that might be triggered by orbiting planets. We present detailed 3-D radiation-hydrodynamic simulations of disks with single and multiple embedded planets, from which we compute synthetic images at near-infrared, mid-infrared, far-infrared, and sub-millimeter wavelengths, enabling a direct comparison of the signatures that are detectable with PFI and complementary facilities such as ALMA. From these simulations, we derive some preliminary specifications that will guide the array design and technology roadmap of the facility.
  31. Rinehart, S., Carpenter, K., van Belle, G., Unwin, S., 2014, SPIE, 9146, 914617, Interferometer evolution: imaging terras after building 'little' experiments (INEVITABLE)
    Perhaps one of the most ambitious long-term goals of the astronomical community is to map distant exoplanets. This will require instruments that provide sufficient angular resolution to place multiple pixels across an image of an exoplanet. Many other science programs also require orders of magnitude improvement in angular resolution, and for all of these, single aperture telescopes are impractical. In fact, the array of scientific goals that require high angular resolution makes interferometry inevitable. Here, we discuss some of the long-term science needs, and the implications for future interferometers, and then talk about some possible paths towards these future missions.
  32. Sun, B., Jorgensen, A., Landavazo, M., Hutter, D., van Belle, G., Mozurkewich, D., Armstrong, J., Schmitt, H., Baines, E., Restaino, S., 2014, SPIE, 9146, 914620, The new classic data acquisition system for NPOI
    The New Classic data acquisition system is an important portion of a new project of stellar surface imaging with the NPOI, funded by the National Science Foundation, and enables the data acquisition necessary for the project. The NPOI can simultaneously deliver beams from 6 telescopes to the beam combining facility, and in the Classic beam combiner these are combined 4 at a time on 3 separate spectrographs with all 15 possible baselines observed. The Classic data acquisition system is limited to 16 of 32 wavelength channels on two spectrographs and limited to 30 s integrations followed by a pause to ush data. Classic also has some limitations in its fringe-tracking capability. These factors, and the fact that Classic incorporates 1990s technology which cannot be easily replaced are motivation for upgrading the data acquisition system. The New Classic data acquisition system is based around modern electronics, including a high-end Stratix FPGA, a 200 MB/s Direct Memory Access card, and a fast modern Linux computer. These allow for continuous recording of all 96 channels across three spectrographs, increasing the total amount of data recorded by a an estimated order of magnitude. The additional computing power on the data acquisition system also allows for the implementation of more sophisticated fringe-tracking algorithms which are needed for the Stellar Surface Imaging project. In this paper we describe the New Classic system design and implementation, describe the background and motivation for the system as well as show some initial results from using it.
  33. Landavazo, M., Jorgensen, A., Sun, B., Newman, K., Mozurkewich, D., van Belle, G., Hutter, D., Schmitt, H., Armstrong, J., Baines, E., Restaino, S., 2014, SPIE, 9146, 914621, 6-station, 5-baseline fringe tracking with the new classic data acquisition system at the Navy Precision Optical Interferometer
    The Navy Precision Optical Interferometer (NPOI) has a station layout which makes it uniquely suited for imaging. Stellar surface imaging requires a variety of baseline lengths and in particular long baselines with resolution much smaller than the diameter of the target star. Because the fringe signal-to-noise ratio (SNR) is generally low on such long baselines, fringe-tracking cannot be carried out on those baselines directly. Instead, baseline bootstrapping must be employed in which the long baseline is composed of a number of connected shorter baselines. When fringes are tracked on all the shorter baselines fringes are also present on the long baseline. For compact sources, such as stellar disks, the shorter baselines generally have higher SNR and making them short enough that the source is unresolved by them is ideal. Thus, the resolution, or number of pixels across a stellar disk, is roughly equal to the ratio of the length of the long baseline to the length of the short baselines. The more bootstrapped baselines, the better the images produced. If there is also a wide wavelength coverage, wavelength bootstrapping can also be used under some circumstances to increase the resolution further. The NPOI is unique in that it allows 6-station, 5-baseline bootstrapping, the most of any currently operating interferometer. Furthermore, the NPOI Classic beam combiner has wavelength coverage from 450 nm to 850 nm. However, until now, this capability has not been fully exploited. The stellar surface imaging project which was recently funded by the National Science Foundation is exploiting this capability. The New Classic data acquisition system, reported separately, is the hardware which delivers the data to the fringe-tracking algorithm. In this paper we report on the development of the fringe-tracking capability with the New Classic data acquisition system. We discuss the design of the fringe tracking algorithm and present performance results from simulations and on sky observation.
  34. Newman, K., Jorgensen, A., Landavazo, M., Sun, B., Hutter, D., Armstrong, J., Mozurkewich, D., Elias, N., van Belle, G., Schmitt, H., Baines, E., 2014, SPIE, 9146, 914630, Design and implementation of the NPOI database and website
    The Navy Precision Optical Interferometer (NPOI) has been recording astronomical observations for nearly two decades, at this point with hundreds of thousands of individual observations recorded to date for a total data volume of many terabytes. To make maximum use of the NPOI data it is necessary to organize them in an easily searchable manner and be able to extract essential diagnostic information from the data to allow users to quickly gauge data quality and suitability for a specific science investigation. This sets the motivation for creating a comprehensive database of observation metadata as well as, at least, reduced data products. The NPOI database is implemented in MySQL using standard database tools and interfaces. The use of standard database tools allows us to focus on top-level database and interface implementation and take advantage of standard features such as backup, remote access, mirroring, and complex queries which would otherwise be time-consuming to implement. A website was created in order to give scientists a user friendly interface for searching the database. It allows the user to select various metadata to search for and also allows them to decide how and what results are displayed. This streamlines the searches, making it easier and quicker for scientists to find the information they are looking for. The website has multiple browser and device support. In this paper we present the design of the NPOI database and website, and give examples of its use.
  35. Cibulkova, H., Durech, J., Kaasalainen, M., Bowell, E., Oszkiewicz, D., 2014, acm, 103, Distribution of spin axes in the asteroid population
    Currently, the main method for determination of shapes and spin states of asteroids is the inversion of their lightcurves (Kaasalainen et al., 2001). The all-sky surveys such as Pan-STARRS, Catalina Sky Survey and LONEOS produce a lot of photometric data, but these data are sparse in time (only few measurements per night). Although we can derive models from sparse data, this requires sufficiently many photometric measurements with good quality (errors < 0.1 mag). With currently available data, the success rate of getting a unique solution of the inverse problem is low. Therefore, we have developed an alternative approach that models asteroids as geometrically scattering triaxial ellipsoids. The model computes mean brightness and the dispersion of brightness for each observed apparition. The parameters are ecliptic longitude, latitude of the pole, and the ratio of axes of the ellipsoid. These parameters are optimized to reach the best agreement with observed mean brightness and dispersion of brightness. To test the reliability and accuracy of our approach we ran set of simulations with synthetic data based on the complex asteroid shapes from the DAMIT database and Hapke's scattering model. We will present the results of simulations with synthetic data and the distribution of poles derived from real data from the Lowell Observatory database and confront our results with the work Bowell et al. (2014), who used a similar approach and revealed the anisotropic distribution of spin-axis longitudes.
  36. DeMeo, F., Binzel, R., Carry, B., Polishook, D., Moskovitz, N., 2014, acm, 131, Unexpected D-type interlopers in the inner main belt
    Very red featureless asteroids (spectroscopic D-types) are expected to have formed in the outer Solar System far from the Sun [1,2]. They comprise the majority of asteroids in the Jupiter Trojan population, and are also commonly found in the outer main belt and among Hildas. The first evidence for D-types in the inner and middle parts of the main belt was seen in the Sloan Digital Sky Survey (SDSS) [3].

    Here we report follow-up observations of SDSS D-type candidates in the near-infrared. Based on follow up observations of 13 SDSS D-type candidates [4], we find a 20 % positive confirmation rate. Known inner belt D-types range in diameter from roughly 7 to 30 km. Based on these detections we estimate there are 100 inner belt D-types with diameters between 2.5 and 20 km. The lower and upper limits for total mass of inner belt D-types is 210^{16} kg to 210^{17} kg which represents 0.01-0.1 % of the mass of the inner belt [5].

    The inner belt D-types have albedos at or above the upper end typical for D-types [6] which raises the question as to whether these inner belt bodies represent only a subset of D-types, they have been altered by external factors such as weathering processes, or if they are compositionally distinct from other D-types. All D-types and candidates have diameters less than 30 km, yet there is no obvious parent body in the inner belt. Dynamical models (e.g., [7]) have yet to show how D-types originating from the outer Solar System could arrive at the inner reaches of the main belt under current scenarios of planet formation and subsequent Yarkovsky drift.

  37. DeMeo, F., Carry, B., Binzel, R., Moskovitz, N., Polishook, D., Burt, B., 2014, acm, 132, The distribution of mantle material in the main belt
    We expect there to have been many differentiated asteroids in the Main Asteroid Belt (MB) earlier in the solar system's history because the diversity of iron meteorites imply the existence of over 60 distinct parent bodies [1]. Searches have been performed to identify basaltic crust material (spectral V-type asteroids) in the outer MB (e.g., [2--5]). Many basaltic bodies distributed throughout the MB have been discovered within the past decade. The olivine-rich mantles of differentiated asteroids should have produced substantially greater volumes (and therefore substantially greater numbers) of remnant asteroids compared with basaltic and iron samples. Yet olivine-rich asteroids (A-types) are one of the rarest asteroid types [6,7].

    An alternative way to search for differentiated bodies that have been heavily or completely disrupted is to identify these spectral A-type asteroids, characterized by a very wide and deep 1-micron absorption indicative of large amounts (> 80 %) of olivine. They are close spectral matches (although much redder due to space weathering) to Brachinite or Pallasite meteorites (e.g., [8]) and are thought to represent mantle material or core-mantle boundary material of disrupted differentiated asteroids. [9] proposed that these asteroids are only found among the largest because most were ''battered to bits'' due to collisions, so smaller A-types were below our detection limit.

    Using the Sloan Digital Sky Survey Moving Object Catalog to select A-type asteroid candidates, we have conducted a near-infrared spectral survey of asteroids over 12 nights in the near-infrared in an effort to determine the distribution and abundance of crustal and mantle material across the MB. From three decades of asteroid spectral observations, only 10 A-type asteroids have been discovered. In our survey, we have detected > 20 new A-type asteroids thus far throughout the belt, tripling the number of known A-types. We present these spectra and their distribution throughout the MB. We estimate the total mass of mantle material present in the belt today and discuss the implications.

  38. French, L., Stephens, R., Coley, D., Wasserman, L., 2014, acm, 169, Lightcurves and rotational periods of comet-sized Jovian Trojan asteroids
    The Jovian Trojans are among the most enigmatic objects in the Solar System. They have been studied less than main-belt asteroids because of their low albedos and greater distance from the Sun. Several lines of evidence support a common origin for the Jovian Trojan asteroids and cometary nuclei. Their spectra and low albedos bear a strong resemblance to those of comets. The Nice Model predicts that the Trojans may well be objects that originated with today's Kuiper Belt Objects which predicts that today's Trojans were trapped in their current locations at Jupiter's L4 and L5 points after Saturn and Jupiter passed through a 2:1 resonance.

    We are surveying Trojan rotation properties to test the Nice Model hypothesis. One approach is a comparison of rotation properties of similar-sized Trojans and comets. We present new lightcurve information for several Trojans 30 km in diameter, more than doubling the number of objects in this size range for which some rotation information is known. The minimum densities for objects with complete lightcurves are estimated and are found to be comparable to those measured for cometary nuclei.

    Observations were obtained using the Cerro Tololo (CTIO) Blanco 4-m telescope, the CTIO 0.9-m telescope, and 0.4-m and 0.35-m telescopes at the Center for Solar System Studies (CS3) from 2011 August to 2014 May. The lower limit of densities of the small Trojans in our study are comparable to the densities for the two Trojans which have been directly measured, and those of similar sized comets. These results suggest these Trojans have an icy composition with significant amount of internal space; they are consistent with a comet-like composition for these bodies.

  39. Knight, M., 2014, acm, 275, Sungrazing comets: Probing the inner extremes of the Solar System
    Comet ISON (C/2012 S1) gained much notoriety as the first known dynamically new sungrazing comet, and was observed extensively leading up to its perihelion passage in November 2013. While ISON's destruction near perihelion was disappointing, its intense study will yield unprecedented insight into the behavior of sungrazing comets. In light of this heightened interest in sungrazing comets, I will present a brief overview of the populations of sungrazing comets and review what their study has revealed about the solar system.

    Our knowledge of the near-Sun environment has been revolutionized over the last few decades by the discovery of thousands of faint comets on sungrazing orbits. The vast majority of these objects are seen only by the telescopes onboard SOlar and Heliospheric Observatory (SOHO) and/or Solar-TErrestrial RElations Observatory (STEREO), with observations typically spanning hours to a few days. About 85 % are dynamically related to each other as members of the Kreutz group, whose members were likely produced by cascading fragmentation from a single parent in the last few thousand years. The Kreutz group was the only group of sungrazing comets known prior to the modern space-based coronagraphic era, and includes such spectacular naked eye objects as Ikeya-Seki (1965f = C/1965 S1) and Lovejoy (C/2011 W3). Kreutz comets are seen in SOHO and STEREO images on average every few days and all but the largest historical comets are destroyed during the tiny perihelion passage (1--2 solar radii). At least three additional groups of near-Sun comets, sometimes termed ''sunskirting'' due to their moderately larger perihelion distances (8--12 solar radii) have been discovered in SOHO and STEREO images. As a result of the decreased insolation and tidal forces sustained during their perihelion passages, many sunskirters survive perihelion. Two sunskirting groups, the Marsden and Kracht groups have short (4--6 yr) orbital periods and are dynamically related to comet 96P/Machholz 1. The third group, Meyer, has not been linked to any known solar system object and has an unknown orbital period. The remaining known sungrazing comets have a variety of orbits and, with the notable exception of ISON, are generally not observed extensively.

    Due to their extreme orbits, sungrazing comets offer unique opportunities for understanding evolutionary processes in our solar system. During their perihelion passages they experience equilibrium temperatures exceeding 1500 K, resulting in sublimation of their dust and potentially allowing the least volatile components of our solar system to be cataloged. In fact, while all of the near-Sun objects discovered by SOHO and STEREO are designated ''comets'', many of those not associated with other known cometary objects may be asteroids or defunct comets whose apparent activity at these distances is due to sublimation of their bare surfaces. Sungrazing comets also experience strong tidal forces, resulting in frequent fragmentation. Such breakups expose the unprocessed interiors, potentially allowing intercomparison of the compositions of discrete fragments and revealing the size distribution of the planetessimals out of which the parent comet formed. Finally, it has recently become possible to use comets as ''solar probes'', treating them as test particles that can reveal properties of the solar environment such as the coronal temperature and density, magnetic field strength, and solar wind speed and direction.

  40. Knight, M., Begun, J., Kelley, M., Battams, K., A'Hearn, M., 2014, acm, 276, The combined SOHO-STEREO dataset: Simultaneous observations of comets from multiple vantage points
    The set of comets observed by Solar and Heliospheric Observatory (SOHO) and Solar-TErrestrial RElations Observatory (STEREO) provides a large (>2500 comets) and unique database for studying cometary properties. Sungrazing comets are discovered in SOHO or STEREO images on average every few days, with individual comets typically observable for up to a few days. We compiled photometry of more than 20 comets observed simultaneously by the same telescope and filter on both STEREO spacecraft to construct the first dust scattering phase function ever directly computed from simultaneous observations of the same object from two vantage points, thus removing uncertainty caused by changing heliocentric distance between observations. The collective dust scattering phase function spans phase angles from 28--153 deg and agrees reasonably well with the theoretical curve from [1]. However, individual comets deviate from the predicted curve by varying amounts during their apparition. This may suggest that the dust properties of individual comets change on the timescale of hours due to the dramatically different heliocentric distance or that the number of dust grains in the coma is changing due to nucleus activity, rotation, and/or erosion. We have also begun a study of the dust tails of selected well-observed comets in our database. This project utilizes the 3-D aspects of the combined SOHO and STEREO dataset to constrain the dust properties and time of release better than is possible with observations from a single location. We will present ongoing results of these investigations and place them into the wider context of sungrazing comet studies, notably by comparison with SOHO and STEREO observations of comet C/2012 S1 ISON [2], the most extensively observed sungrazing comet in history.
  41. Lim, L., Moskovitz, N., Thomas, C., Howell, E., Emery, J., Benner, L., 2014, acm, 318, Thermal emission photometry of three near-Earth asteroids in L' and M'
    We acquired JKL'M' (1.2--4.7 microns; [1]) spectrophotometry of three sub-km near-Earth asteroid radar targets during 2013. Thermal emission measurements in L' and M' were taken in order to characterize the sizes and thermal properties of the targets. Reflectance data in J and K were taken to aid in separating the thermal from the reflected flux in L'. In addition, we used the J band as a reference filter to characterize the rotational variability in the asteroid lightcurves during the thermal observations.

    Asteroid (163249) 2002 GT was observed using NIRI on Gemini North [2]. Numerous coordinating observations of this asteroid were made as part of a campaign to characterize it in advance of a potential spacecraft encounter (e.g. [3]) which resulted in a rotation period of 3.77 h and an S-complex spectral classifcation (likely Sq or Q, [4,5,6]). The H magnitude was determined to be H=18.63 0.04 and the R-band magnitude slope parameter to be G=0.18 0.02 (formal errors; real errors up to 2x higher (P. Pravec, pers. comm.)).

    Potentially-hazardous asteroids (277475) 2005 WK_4 and (137126) 1999 CF_9 were observed with NSFCam2 on the IRTF [7] and were also successfully measured from the Goldstone and/or Arecibo radar observatories. Radar imaging of 2005 WK_4 shows a spheroidal shape and a diameter of 250 20 m. SpeX data indicate that both 2005 WK_4 and 1999 CF_9 are also S-complex objects. Further analysis of these data is in progress.

  42. Moskovitz, N., Manos Team, 2014, acm, 366, The Mission Accessible Near-Earth Object Survey (MANOS)
    Near-Earth objects (NEOs) are essential to understanding the origin of the Solar System through their compositional links to meteorites. As tracers of various regions within the Solar System they can provide insight to more distant, less accessible populations. Their relatively small sizes and complex dynamical histories make them excellent laboratories for studying ongoing Solar System processes such as space weathering, planetary encounters, and non-gravitational dynamics. Knowledge of their physical properties is essential to impact hazard assessment. Finally, the proximity of NEOs to Earth make them favorable targets for robotic and human exploration. However, in spite of their scientific importance, only the largest (km-scale) NEOs have been well studied and a representative sample of physical characteristics for sub-km NEOs does not exist.

    To address these issues we are conducting the Mission Accessible Near-Earth Object Survey (MANOS), a fully allocated multi-year survey of sub-km NEOs that will provide a large, uniform catalog of physical properties including light curves, spectra, and astrometry. From this comprehensive catalog, we will derive global properties of the NEO population, as well as identify individual targets that are of potential interest for exploration. We will accomplish these goals for approximately 500 mission-accessible NEOs across the visible and near-infrared ranges using telescope assets in both the northern and southern hemispheres. MANOS has been awarded large survey status by NOAO to employ Gemini-N, Gemini-S, SOAR, the Kitt Peak 4 m, and the CTIO 1.3 m. Access to additional facilities at Lowell Observatory (DCT 4.3 m, Perkins 72'', Hall 42'', LONEOS), the University of Hawaii, and the Catalina Sky Survey provide essential complements to this suite of telescopes.

    Targets for MANOS are selected based on three primary criteria: mission accessibility (i.e. v < 7 km/s), size (H > 20), and observability. Our telescope assets allow us to obtain rotational light curves for objects down to V22, visible spectra down to V21, and near-IR spectra down to V19. MANOS primarily focuses on targets that are recently discovered. We employ a regular cadence of remote and queue observations to enable follow-up characterization within days or weeks after a target of interest is discovered.

    We will present a MANOS status report with an emphasis on noteworthy observations and ongoing efforts to achieve fully transparency by making target lists and data products publicly available online.

  43. Moskovitz, N., Polishook, D., DeMeo, F., Binzel, R., Endicott, T., Yang, B., Howell, E., Vervack, R., Fernandez, Y., 2014, acm, 367, Detection of aspect-dependent thermal emission as a signature of near-Earth asteroid pole orientation
    Spin vectors are intimately related to the efficiency in which the Yarkovsky and YORP effects can change the orbital, rotational, and physical properties of minor planets (e.g., [1,2]) Despite the importance of spin vectors, only a few dozen asteroids have well constrained pole orientations. This is due to the years or even decades required to constrain spin vectors with astrometric, photometric or radar observations (e.g. [3,4,5]). Here we constrain the spin vector of the near-Earth asteroid (285263) 1998 QE_2 in a single apparition (3 months) by monitoring its thermal emission as a function of phase angle ().

    We obtained near-infrared spectra of QE_2 between May and July of 2013 with SpeX at NASA's Infrared Telescope Facility. The low 6 % albedo of QE_2 [6] enabled the detection of thermal emission at near-IR wavelengths >2 m. We modeled this thermal emission with the near-Earth asteroid thermal model, NEATM [7]. QE_2 is a well-characterized object with known albedo, diameter, spectral type, and absolute magnitude, thus the only free parameter in our NEATM models was the thermal beaming parameter . We find a specific relationship between and phase angle, which is fully consistent with a putative prograde rotation state [8] and a surface thermal inertia of 200 J m^{-2} s^{-0.5} K^{-1} [9]; the latter is in line with expectations for 3 km asteroids like QE_2 [10]. This technique can be applied to low-obliquity near-Earth asteroids smaller than 5 km that are observable across a range of phase angles >30 degrees in a single apparition.

  44. Oszkiewicz, D., Bowell, E., Wasserman, L., Muinonen, K., Penttila, A., 2014, acm, 402, Asteroid taxonomy and the H,G_{12} magnitude system
    We review the asteroid magnitude systems. The conventionally used H,G system (approved by the IAU in 1985) was recently replaced by the H,G_{12} and H,G_1,G_2 systems (approved by the IAU in 2012). The new phase curves were already applied to a large quantity of photometric data (Oszkiewicz et al, 2011). In particular, absolute magnitudes and slope parameters were computed for about half a million asteroids and are publicly available through the Planetary Research Group (University of Helsinki) websites. Several correlations of the shape of the phase curves with asteroid physical parameters were also explored. In general, the steepness of a phase curve relates to the physical properties of an asteroid's surface such as for example composition, porosity, packing density, roughness, and grain size distribution. However, most of those cannot be studied with the currently available data. Some conclusions regarding links to albedo and taxonomy can still be made. First, the G_1 and G_2 parameters correlate with albedo. Generally, the higher the albedo the lower and higher are the G_1 and G_2 parameters, respectively. Second, the G_{12} parameter distributions for the different asteroid taxonomic complexes are statistically different. For example, the C-complex asteroids tend to have high G_{12}'s, S-complex asteroids low G_{12}'s, and objects from the X-complex lean towards average values (Oszkiewicz et al. 2012). Additionally, asteroid families with a few exceptions show homogeneity of the G_{12} parameter (Figure). This is yet another confirmation of homogeneity of asteroid families and therefore the overall tendency to retain the same physical properties across family members.

    We study the usability of the G_{12} parameter in topics such as breaking the X-complex degeneracy and taxonomical classification. In particular, we combine the G_{12}'s with the Sloan Digital Sky Survey (SDSS) and the Wide-Field Infrared Survey Explorer (WISE) data (Oszkiewicz et al. 2014) to investigate the predictability of taxonomic complexes.

  45. Polishook, D., Moskovitz, N., DeMeo, F., Binzel, R., 2014, acm, 421, Rotationally resolved spectroscopy of asteroid pairs: No spectral variation detected
    Introduction: The split of an asteroid due to a fast rotation [1] can expose sub-surface material that was never altered before by the Space Weathering mechanism [2]. We were searching for the ''location of fission'' on asteroid pairs --- asteroids that were disrupted in the last 2 million years [3]. We studied the possibility that the sub-surface material has different spectral characteristics than the original weathered surface, by performing rotationally resolved spectroscopic observations and looking for local variations as the asteroid rotates.

    Method: We spectrally observed 11 asteroids in pairs in near-IR with the IRTF/SpeX and visible range with Magellan/LDSS3. Photometric observations were also conducted at the Wise Observatory (Israel) to derive the asteroid lightcurves and to determine the rotational phases where the spectral observations took place and to verify that the asteroid is not observed pole-on.

    Results: We could not find a single case of a repeating, significant and convincing, spectral variation within the noise of our measurements. For each observed segment of an asteroid we estimate the maximal size of an undetected ''spot'' with a spectral signature different than the average. In some cases (asteroids 2110, 6070, 10484, 25884 and 63440), the maximal diameter of such a ''spot'' is significantly smaller than the diameter of the secondary member of the asteroid. Therefore, we can conclude that at least for these asteroids the ''location of fission'' does not have different spectral signature.

    Discussion: The specific case of asteroid 6070 can reveal the way pairs are formed: The time for its fission (17 kyr [3]) is shorter than any suggested timescale of space weathering [e.g., 4,5,6]; indeed, its secondary member 54827 presents fresh, Q-type, reflectance spectrum [7]. However, 6070 presents more mature reflectance spectrum (Sq-type). Since its ''location of fission'' does not present spectral variation compared to the rest of the surface as demonstrated by our study, we can conclude that the rotational-fission process is followed by the spread of dust, as seen in the disintegration event of the asteroid P/2013 R3 [8], that re-accumulates on the primary asteroid and covers it homogeneously, preventing the appearance of a ''fresh spot'' on its surface.

  46. Schleicher, D., Bair, A., 2014, acm, 475, Chemical and physical properties of comets in the Lowell database: Results from 35 years of narrow-band 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. Consequently, differences in the chemical composition among comets can indicate either differences in protoplanetary material and primordial conditions in our solar system or subsequent evolutionary effects. By gathering chemical and physical data on a large sample of comets and correlating these with dynamical properties, we can perform statistical analyses to determine the actual cause of a specific difference in properties. We have recently completed a new uniform reduction and set of analyses of the Lowell comet database, which includes 35 years of narrowband photometry of 167 comets. To minimize uncertainties due to too few data points or other systematics, a restricted subset of the database was created for chemical compositional studies, and mean abundance ratios were computed for each of these 101 comets. We used a variety of taxonomic techniques to identify seven compositional classes and to determine the membership of each class. Several classes are simply sub-groups of the original carbon-chain depleted class as defined by A'Hearn et al. (1995); 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. Among the other new classes is one containing five comets that are depleted in ammonia but are not depleted in carbon-chain molecules, but it is unclear if this compositional class is primordial or not.

    Other, non-compositional analyses were performed, using appropriate sub-sets of the entire database for each investigation. These included active areas, active fractions, and the behavior of the dust-to-gas ratio. Regarding the dust-to-gas ratio, we observed trends with respect to both perihelion distance and to age, implying an evolution of the surface of the nucleus associated with the peak temperature attained and how often it has been reached. Details of these and other results will be presented.

  47. Scott, E., Goldstein, J., Asphaug, E., Bottke, W., Moskovitz, N., Keil, K., 2014, acm, 483, Origin of igneous meteorites and differentiated asteroids
    Introduction: Igneously formed meteorites and asteroids provide major challenges to our understanding of the formation and evolution of the asteroid belt. The numbers and types of differentiated meteorites and non-chondritic asteroids appear to be incompatible with an origin by fragmentation of numerous Vesta-like bodies by hypervelocity impacts in the asteroid belt over 4 Gyr. We lack asteroids and achondrites from the olivine-rich mantles of the parent bodies of the 12 groups of iron meteorites and the 70 ungrouped irons, the 2 groups of pallasites and the 4--6 ungrouped pallasites. We lack mantle and core samples from the parent asteroids of the basaltic achondrites that do not come from Vesta, viz., angrites and the ungrouped eucrites like NWA 011 and Ibitira. How could core samples have been extracted from numerous differentiated bodies when Vesta's basaltic crust was preserved? Where is the missing Psyche family of differentiated asteroids including the complementary mantle and crustal asteroids [1]? Why are meteorites derived from far more differentiated parent bodies than chondritic parent bodies even though C and S class chondritic asteroids dominate the asteroid belt?

    New paradigm. Our studies of meteorites, impact modeling, and dynamical studies suggest a new paradigm in which differentiated asteroids accreted at 1--2 au less than 2 Myr after CAI formation [2]. They were rapidly melted by 26Al and disrupted by hit-and-run impacts [3] while still molten or semi-molten when planetary embryos were accreting. Metallic Fe-Ni bodies derived from core material cooled rapidly with little or no silicate insulation less than 4 Myr after CAI formation [4]. Fragments of differentiated planetesimals were subsequently tossed into the asteroid belt.

    Meteorite evidence for early disruption of differentiated asteroids. If iron meteorites were samples of Fe-Ni cores of bodies that cooled slowly inside silicate mantles over 50--100 Myr, irons from each core would have almost indistinguishable cooling rates as thermal gradients across cores would have been minimal. Irons in groups IIIAB, IVA, and IVB have chemical crystallization trends showing that they cooled in three separate bodies. However, each shows a wide range of cooling rates [4]. Group IVA irons cooled through 500C at 6600--100 C/Myr in a metallic body of radius 150 50 km with scarcely any silicate insulation [5]. The Pb-Pb age of 4565.3 0.1 Myr for a IVA iron [6] confirms that these irons cooled to 300C only 2--3 Myr after CAI formation. Multiple hit-and-run impacts may have separated core and mantle material during accretion [7] as hypervelocity impacts do not efficiently separate cores from mantles. Thermal histories and magnetic properties of main group pallasites also require early catastrophic disruption of their primary parent body [8,9].

    Conclusions. The anomalous properties of differentiated asteroids and meteorites cannot be explained by concealing differentiated planetesimals under chondritic crusts [10] as meteorite breccias and the apparent compositional homogeneity of asteroid families are inconsistent with this model. Like Burbine et al. [11], we attribute the lack of olivine mantle meteorites and asteroids to collisional grinding of weaker silicate and the preferential survival of stronger metallic Fe,Ni fragments. But we infer that asteroid break up occurred very early inside 2 au, not in the asteroid belt over 4 Gyr. Vesta may have preserved its crust due to early ejection into the asteroid belt. It is the smallest terrestrial planet --- not an archetypal differentiated asteroid.

  48. Thomas, C., Rivkin, A., Trilling, D., Moskovitz, N., 2014, acm, 525, Spectra of small Koronis family members
    The space-weathering process and its implications for the relationships between S- and Q-type asteroids and ordinary chondrite meteorites are long-standing problems in asteroid science. Although the visible and near-infrared spectra of S- and Q-type objects qualitatively show the same absorption features and quantitatively show evidence of the same minerals, the S types display increased spectral slopes and muted absorption features compared to the Q types. This spectral mismatch is consistent with the effects of the space weathering process. Binzel et al. provided the missing link between Q- and S-type bodies in near-Earth space by showing a reddening of spectral slope in objects from 0.1 to 5 km that corresponded to the transition from Q- to S-type spectra. This result implied that size, and therefore age, is related to the relationship between Q- and S-type. The existence of Q-type objects in the main belt was not confirmed until Mothe-Diniz and Nesvorny (2008) found them in young S-type clusters. To investigate the trend from Q to S in the main belt, we examined space weathering within the old main-belt Koronis family using a spectrophotometric survey (Rivkin et al. 2011, Thomas et al. 2011). Rivkin et al. (2011) identified several potential Q-type objects within the Koronis family.

    Our Q-type candidates were identified using broad-band spectrophotometry and could not be taxonomically classified on that basis alone. We obtained follow-up visible and near-infrared spectral observations of our potential Q-type objects, (26970) Elias, (45610) 2000 DJ_{48}, and (37411) 2001 XF_{152}, using Gemini and Magellan. We will present the results of these spectral follow-up observations. Observations of (26970) Elias demonstrate that the object is more consistent with the average Q-type spectrum than the average S-type spectrum.

  49. Lacasse, M., Lotz, P., 2014, SPIE, 9152, 915205, Discovery Channel Telescope software progress report: addressing early commissioning and operations challenges
    The Discovery Channel Telescope is a 4.3m astronomical research telescope in northern Arizona constructed through a partnership between Discovery Communications and Lowell Observatory. In transition from construction phase to commissioning and operations, we faced a variety of software challenges, both foreseen and unforeseen, and addressed those with a variety of solutions including, isolation of the control systems network, development of an Operations Log application, extension of the interface to instrumentation software, improvements to engineering data analysis, provisions to avoid failure modes, and enhanced user experience. We describe these solutions and present an overview of the current project status.
  50. DeGroff, W., Levine, S., Bida, T., Cornelius, F., Collins, P., Dunham, E., Hardesty, B., Lacasse, M., Sweaton, M., Venetiou, A., Zoonemat Kermani, S., Massey, P., Foley, M., Larson, H., Sanborn, J., Strosahl, S., Winner, R., Pugh, T., 2014, SPIE, 9145, 91452C, Status and performance of the Discovery Channel Telescope from commissioning into early science operations
    Lowell Observatory's Discovery Channel Telescope is a 4.3m telescope designed and constructed for optical and near infrared astronomical observation. It is equipped with a cube capable of carrying five instruments and the wave front sensing and guider systems at the f/6.1 RC focus. We report on the overall operations methods for the facility, including coordination of day and night activities, and then cover pointing, and unguided and guided tracking performance of the mount. We also discuss the implementation and performance of the open loop model for, and manual wavefront sensing and correction with the active optics system. We conclude with a report on the early integrated image quality and science performance of the facility using the first science instrument, the Large Monolithic Imager.
  51. Smith, E., Miles, J., Helton, L., Sankrit, R., Andersson, B., Becklin, E., De Buizer, J., Dowell, C., Dunham, E., Gusten, R., Harper, D., Herter, T., Keller, L., Klein, R., Krabbe, A., Logsdon, S., Marcum, P., McLean, I., Reach, W., Richter, M., Roellig, T., Sandell, G., Savage, M., Temi, P., Vacca, W., Vaillancourt, J., Van Cleve, J., Young, E., 2014, SPIE, 9147, 914706, SOFIA science instruments: commissioning, upgrades and future opportunities
    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is the world's largest airborne observatory, featuring a 2.5 meter effective aperture telescope housed in the aft section of a Boeing 747SP aircraft. SOFIA's current instrument suite includes: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), a 5-40 m dual band imager/grism spectrometer developed at Cornell University; HIPO (High-speed Imaging Photometer for Occultations), a 0.3-1.1m imager built by Lowell Observatory; GREAT (German Receiver for Astronomy at Terahertz Frequencies), a multichannel heterodyne spectrometer from 60-240 m, developed by a consortium led by the Max Planck Institute for Radio Astronomy; FLITECAM (First Light Infrared Test Experiment CAMera), a 1-5 m wide-field imager/grism spectrometer developed at UCLA; FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), a 42-200 m IFU grating spectrograph completed by University Stuttgart; and EXES (Echelon-Cross-Echelle Spectrograph), a 5-28 m highresolution spectrometer designed at the University of Texas and being completed by UC Davis and NASA Ames Research Center. HAWC+ (High-resolution Airborne Wideband Camera) is a 50-240 m imager that was originally developed at the University of Chicago as a first-generation instrument (HAWC), and is being upgraded at JPL to add polarimetry and new detectors developed at Goddard Space Flight Center (GSFC). SOFIA will continually update its instrument suite with new instrumentation, technology demonstration experiments and upgrades to the existing instrument suite. This paper details the current instrument capabilities and status, as well as the plans for future instrumentation.
  52. Dunham, E., Bida, T., Collins, P., Mandushev, G., Zoonematkermani, S., Van Cleve, J., Angerhausen, D., Mandell, A., 2014, SPIE, 9147, 91470H, HIPO in-flight performance improvements
    The High-speed Imaging Photometer for Occultations (HIPO) is a special purpose science instrument for SOFIA. HIPO can be co-mounted with FLITECAM in the so-called FLIPO configuration for stellar occultation or extrasolar planet transit observations. We gained some flight experience with HIPO and FLITECAM in 2011 as described in a previous publication (Dunham, et al., Proc SPIE, 8446-42, 2012). Since that time a number of improvements to HIPO have been made and a deeper understanding of the airborne environment's impact on photometric precision at optical wavelengths has been obtained. The improvements to HIPO include an improved beamsplitter for the FLIPO configuration, adding deep depletion CCDs as a detector option, expanding the filter set to include a Sloan Digital Sky Survey filter set as well as two custom filters for transit work, and an ability to guide the SOFIA telescope using HIPO data being acquired for science purposes. We now understand that variations in PSF size due to varying static air density has a noticeable impact on photometric stability while the related effect of Mach number is unimportant. The seriousness of ozone absorption in the Chappuis band is now understood and an approach to avoid this has been found. Finally we present demonstration transit data to illustrate our current transit photometry capability.
  53. Bida, T., Dunham, E., Massey, P., Roe, H., 2014, SPIE, 9147, 91472N, First-generation instrumentation for the Discovery Channel Telescope
    The 4.3m Discovery Channel Telescope (DCT) has been conducting part-time science operations since January 2013. The f/6.1, 0.5 field-of-view at the RC focus is accessible through the Cassegrain instrument cube assembly, which can support 5 co-mounted instruments with rapid feed selection via deployable fold mirrors. Lowell Observatory has developed the Large Monolithic Imager (LMI), a 12.3' FOV 6K x 6K single CCD camera with a dual filter wheel, and installed at the straight-through, field-corrected RC focal station, which has served as the primary early science DCT instrument. Two low-resolution facility spectrographs are currently under development with first light for each anticipated by early 2015: the upgraded DeVeny Spectrograph, to be utilized for single object optical spectroscopy, and the unique Near-Infrared High-Throughput Spectrograph (NIHTS), optimized for single-shot JHK spectroscopy of faint solar system objects. These spectrographs will be mounted at folded RC ports, and the NIHTS installation will feature simultaneous optical imaging with LMI through use of a dichroic fold mirror. We report on the design, construction, commissioning, and progress of these 3 instruments in detail. We also discuss plans for installation of additional facility instrumentation on the DCT.
  54. Logsdon, S., McLean, I., Becklin, E., Dunham, E., Hamilton, R., Johnson, C., Milburn, J., Savage, M., Shenoy, S., Smith, E., Vacca, W., 2014, SPIE, 9147, 91472Y, FLITECAM: early commissioning results
    We present a status report and early commissioning results for FLITECAM, the 1-5 micron imager and spectrometer for SOFIA (the Stratospheric Observatory for Infrared Astronomy). In February 2014 we completed six flights with FLITECAM mounted in the FLIPO configuration, a co-mounting of FLITECAM and HIPO (High-speed Imaging Photometer for Occultations; PI Edward W. Dunham, Lowell Observatory). During these flights, the FLITECAM modes from ~1-4 m were characterized. Since observatory verification flights in 2011, several improvements have been made to the FLITECAM system, including the elimination of a light leak in the FLITECAM filter wheel enclosure, and updates to the observing software. We discuss both the improvements to the FLITECAM system and the results from the commissioning flights, including updated sensitivity measurements. Finally, we discuss the utility of FLITECAM in the FLIPO configuration for targeting exoplanet transits.
  55. Muirhead, P., Becker, J., Feiden, G., Rojas-Ayala, B., Vanderburg, A., Price, E., Thorp, R., Law, N., Riddle, R., Baranec, C., Hamren, K., Schlawin, E., Covey, K., Johnson, J., Lloyd, J., 2014, ApJS, 213, 5, Characterizing the Cool KOIs. VI. H- and K-band Spectra of Kepler M Dwarf Planet-candidate Hosts
    We present H- and K-band spectra for late-type Kepler Objects of Interest (the "Cool KOIs"): low-mass stars with transiting-planet candidates discovered by NASA's Kepler Mission that are listed on the NASA Exoplanet Archive. We acquired spectra of 103 Cool KOIs and used the indices and calibrations of Rojas-Ayala et al. to determine their spectral types, stellar effective temperatures, and metallicities, significantly augmenting previously published values. We interpolate our measured effective temperatures and metallicities onto evolutionary isochrones to determine stellar masses, radii, luminosities, and distances, assuming the stars have settled onto the main sequence. As a choice of isochrones, we use a new suite of Dartmouth predictions that reliably include mid-to-late M dwarf stars. We identify five M4V stars: KOI-961 (confirmed as Kepler 42), KOI-2704, KOI-2842, KOI-4290, and the secondary component to visual binary KOI-1725, which we call KOI-1725 B. We also identify a peculiar star, KOI-3497, which has Na and Ca lines consistent with a dwarf star but CO lines consistent with a giant. Visible-wavelength adaptive optics imaging reveals two objects within a 1 arcsec diameter; however, the objects' colors are peculiar. The spectra and properties presented in this paper serve as a resource for prioritizing follow-up observations and planet validation efforts for the Cool KOIs and are all available for download online using the "data behind the figure" feature.
  56. Guilloteau, S., Simon, M., Pietu, V., Di Folco, E., Dutrey, A., Prato, L., Chapillon, E., 2014, A&A, 567, A117, The masses of young stars: CN as a probe of dynamical masses

    Aims: We attempt to determine the masses of single or multiple young T Tauri and HAeBe stars from the rotation of their Keplerian disks.
    Methods: We used the IRAM PdBI interferometer to perform arcsecond resolution images of the CN N = 2-1 transition with good spectral resolution. Integrated spectra from the 30 m radiotelescope show that CN is relatively unaffected by contamination from the molecular clouds. Our sample includes 12 sources, among which isolated stars like DM Tau and MWC 480 are used to demonstrate the method and its accuracy. We derive the dynamical mass by fitting a disk model to the emission, a process giving M/D, the mass-to-distance ratio. We also compare the CN results with higher resolution CO data, that are however affected by contamination.
    Results: All disks are found in nearly perfect Keplerian rotation. We determine accurate masses for 11 stars, in the mass range 0.5 to 1.9 M. The remaining one, DG Tau B, is a deeply embedded object for which CN emission partially arises from the outflow. With previous determinations, this leads to 14 (single) stars with dynamical masses. Comparison with evolutionary tracks, in a distance independent modified HR diagram, show good overall agreement (with one exception, CW Tau), and indicate that measurement of effective temperatures are the limiting factor. The lack of low mass stars in the sample does not allow to distinguish between alternate tracks.

    Based on observations carried out with the IRAM Plateau de Bure interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).Appendices are available in electronic form at http://www.aanda.org

  57. Paust, N., Wilson, D., van Belle, G., 2014, AJ, 148, 19, Reinvestigating the Clusters Koposov 1 and 2
    We investigate the fundamental parameters of age, distance, and mass function slope for the poorly studied clusters Koposov 1 and Koposov 2. These clusters were discovered recently and tentatively classified as globular clusters. Using the Large Monolithic Imager on Lowell Observatory's Discovery Channel Telescope, we present photometry extending to V = 25, three to four magnitudes below the main sequence turnoffs for the clusters. We find the clusters have tidal radii of 15 pc and 10.7 pc and distances of 34.9 kpc and 33.3 kpc for Koposov 1 and Koposov 2, respectively. Studying the stellar content of the clusters, we use completeness-corrected star counts to reveal extremely faint total magnitudes of 2.01 and 0.03 in V, and steep Salpeter-like present-day mass functions. Finally, we show that the spatial positions of the clusters agree well with the position of the Sagittarius stream and conclude that these two objects are open clusters removed from the Sagittarius galaxy.
  58. Kelly, P., Fox, O., Filippenko, A., Cenko, S., Prato, L., Schaefer, G., Shen, K., Zheng, W., Graham, M., Tucker, B., 2014, ApJ, 790, 3, Constraints on the Progenitor System of the Type Ia Supernova 2014J from Pre-explosion Hubble Space Telescope Imaging
    We constrain the properties of the progenitor system of the highly reddened Type Ia supernova (SN Ia) 2014J in Messier 82 (M82; d 3.5 Mpc). We determine the supernova (SN) location using Keck-II K-band adaptive optics images, and we find no evidence for flux from a progenitor system in pre-explosion near-ultraviolet through near-infrared Hubble Space Telescope (HST) images. Our upper limits exclude systems having a bright red giant companion, including symbiotic novae with luminosities comparable to that of RS Ophiuchi. While the flux constraints are also inconsistent with predictions for comparatively cool He-donor systems (T <~ 35,000 K), we cannot preclude a system similar to V445 Puppis. The progenitor constraints are robust across a wide range of RV and AV values, but significantly greater values than those inferred from the SN light curve and spectrum would yield proportionally brighter luminosity limits. The comparatively faint flux expected from a binary progenitor system consisting of white dwarf stars would not have been detected in the pre-explosion HST imaging. Infrared HST exposures yield more stringent constraints on the luminosities of very cool (T < 3000 K) companion stars than was possible in the case of SN Ia 2011fe.
  59. Grundy, W., Benecchi, S., Porter, S., Noll, K., 2014, Icar, 237, 1, The orbit of transneptunian binary Manwe and Thorondor and their upcoming mutual events
    A new Hubble Space Telescope observation of the 7:4 resonant transneptunian binary system (385446) Manwe has shown that, of two previously reported solutions for the orbit of its satellite Thorondor, the prograde one is correct. The orbit has a period of 110.18 0.02 days, semimajor axis of 6670 40 km, and an eccentricity of 0.563 0.007. It will be viewable edge-on from the inner Solar System during 2015-2017, presenting opportunities to observe mutual occultation and eclipse events. However, the number of observable events will be small, owing to the long orbital period and expected small sizes of the bodies relative to their separation. This paper presents predictions for events observable from Earth-based telescopes and discusses the associated uncertainties and challenges.
  60. Rabinowitz, D., Benecchi, S., Grundy, W., Verbiscer, A., 2014, Icar, 236, 72, The rotational light curve of (79360) Sila-Nunam, an eclipsing binary in the Kuiper Belt
    We combine long-term photometric observations in multiple band passes to determine the rotational light curve for the binary Kuiper-Belt object (79360) Sila-Nunam. We measure an unambiguous fundamental period of 6.2562 0.002 d, within 0.02% of half the orbital period (Porb = 12.50995 0.00036 d) determined earlier from HST observations resolving the binary. The light curve is double-peaked, and well fit by the sum of two sinusoids: a primary with period Porb/2 and peak-to-peak amplitude 0.120 0.012 mag and a secondary with period Porb and peak-to-peak amplitude 0.044 0.010 mag. Excluding observations within 0.1 deg of opposition, we measure a linear solar phase dependence with slope 0.147 0.018 mag deg-1 and a mean absolute magnitude in the Gunn g band of 6.100 0.006 mag. There is no rotational color variation exceeding 4%. We also observe that eclipses occur centered on light curve minima to within 0.3%, requiring the long axis of at least one of the two bodies to point precisely toward the other. Assuming the binary is doubly synchronous and both rotation axes are aligned with the orbital angular momentum vector, our observations jointly constrain triaxial shape models for Sila and Nunam such that the product of their long-to-intermediate axes ratios is 1.120 0.01. Hence both bodies are elongated by 6%, or else one is elongated by 6-12%, and the other by less than 6%.
  61. Temi, P., Marcum, P., Young, E., Adams, J., Adams, S., Andersson, B., Becklin, E., Boogert, A., Brewster, R., Burgh, E., Cobleigh, B., Culp, S., De Buizer, J., Dunham, E., Engfer, C., Ediss, G., Fujieh, M., Grashuis, R., Gross, M., Harmon, E., Helton, A., Hoffman, D., Homan, J., Hutwohl, M., Jakob, H., Jensen, S., Kaminski, C., Kozarsky, D., Krabbe, A., Klein, R., Lammen, Y., Lampater, U., Latter, W., Le, J., McKown, N., Melchiorri, R., Meyer, A., Miles, J., Miller, W., Miller, S., Moore, E., Nickison, D., Opshaug, K., Pfueller, E., Radomski, J., Rasmussen, J., Reach, W., Reinacher, A., Roellig, T., Sandell, G., Sankrit, R., Savage, M., Shenoy, S., Schonfeld, J., Shuping, R., Smith, E., Talebi, E., Teufel, S., Tseng, T., Vacca, W., Vaillancourt, J., Van Cleve, J., Wiedemann, M., Wolf, J., Zavala, E., Zeile, O., Zell, P., Zinnecker, H., 2014, ApJS, 212, 24, The SOFIA Observatory at the Start of Routine Science Operations: Mission Capabilities and Performance
    The Stratospheric Observatory for Infrared Astronomy (SOFIA) has recently concluded a set of engineering flights for observatory performance evaluation. These in-flight opportunities are viewed as the first comprehensive assessment of the observatory's performance and are used to guide future development activities, as well as to identify additional observatory upgrades. Pointing stability was evaluated, including the image motion due to rigid-body and flexible-body telescope modes as well as possible aero-optical image motion. We report on recent improvements in pointing stability by using an active mass damper system installed on the telescope. Measurements and characterization of the shear layer and cavity seeing, as well as image quality evaluation as a function of wavelength have also been performed. Additional tests targeted basic observatory capabilities and requirements, including pointing accuracy, chopper evaluation, and imager sensitivity. This paper reports on the data collected during these flights and presents current SOFIA observatory performance and characterization.
  62. Massey, P., Neugent, K., Morrell, N., Hillier, D., 2014, ApJ, 788, 83, A Modern Search for Wolf-Rayet Stars in the Magellanic Clouds: First Results
    Over the years, directed surveys and incidental spectroscopy have identified 12 Wolf-Rayet (WR) stars in the Small Magellanic Cloud (SMC) and 139 in the Large Magellanic Cloud (LMC), numbers which are often described as "essentially complete." Yet, new WRs are discovered in the LMC almost yearly. We have therefore initiated a new survey of both Magellanic Clouds using the same interference-filter imaging technique previously applied to M31 and M33. We report on our first observing season, in which we have successfully surveyed ~15% of our intended area of the SMC and LMC. Spectroscopy has confirmed nine newly found WRs in the LMC (a 6% increase), including one of WO-type, only the third known in that galaxy and the second to be discovered recently. The other eight are WN3 stars that include an absorption component. In two, the absorption is likely from an O-type companion, but the other six are quite unusual. Five would be classified naively as "WN3+O3 V," but such a pairing is unlikely given the rarity of O3 stars, the short duration of this phase (which is incommensurate with the evolution of a companion to a WN star), and because these stars are considerably fainter than O3 V stars. The sixth star may also fall into this category. CMFGEN modeling suggests these stars are hot, bolometrically luminous, and N-rich like other WN3 stars, but lack the strong winds that characterize WNs. Finally, we discuss two rare Of?p stars and four Of supergiants we found, and propose that the B[e] star HD 38489 may have a WN companion.

    This paper includes data gathered with the 1 m Swope and 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

  63. Schaefer, G., Prato, L., Simon, M., Patience, J., 2014, AJ, 147, 157, Orbital Motion in Pre-main Sequence Binaries
    We present results from our ongoing program to map the visual orbits of pre-main sequence (PMS) binaries in the Taurus star forming region using adaptive optics imaging at the Keck Observatory. We combine our results with measurements reported in the literature to analyze the orbital motion for each binary. We present preliminary orbits for DF Tau, T Tau S, ZZ Tau, and the Pleiades binary HBC 351. Seven additional binaries show curvature in their relative motion. Currently, we can place lower limits on the orbital periods for these systems; full solutions will be possible with more orbital coverage. Five other binaries show motion that is indistinguishable from linear motion. We suspect that these systems are bound and might show curvature with additional measurements in the future. The observations reported herein lay critical groundwork toward the goal of measuring precise masses for low-mass PMS stars.
  64. Kraus, A., Shkolnik, E., Allers, K., Liu, M., 2014, AJ, 147, 146, A Stellar Census of the Tucana-Horologium Moving Group
    We report the selection and spectroscopic confirmation of 129 new late-type (SpT = K3-M6) members of the Tucana-Horologium moving group, a nearby (d ~ 40 pc), young ( ~ 40 Myr) population of comoving stars. We also report observations for 13 of the 17 known Tuc-Hor members in this spectral type range, and that 62 additional candidates are likely to be unassociated field stars; the confirmation frequency for new candidates is therefore 129/191 = 67%. We have used radial velocities, H emission, and Li6708 absorption to distinguish between contaminants and bona fide members. Our expanded census of Tuc-Hor increases the known population by a factor of ~3 in total and by a factor of ~8 for members with SpT >= K3, but even so, the K-M dwarf population of Tuc-Hor is still markedly incomplete. Our expanded census allows for a much more detailed study of Tuc-Hor than was previously feasible. The spatial distribution of members appears to trace a two-dimensional sheet, with a broad distribution in X and Y, but a very narrow distribution (5 pc) in Z. The corresponding velocity distribution is very small, with a scatter of 1.1 km s-1 about the mean UVW velocity for stars spanning the entire 50 pc extent of Tuc-Hor. We also show that the isochronal age ( ~ 20-30 Myr) and the lithium depletion boundary age ( ~ 40 Myr) disagree, following the trend in other pre-main-sequence populations for isochrones to yield systematically younger ages. The H emission line strength follows a trend of increasing equivalent width with later spectral type, as is seen for young clusters. We find that moving group members have been depleted of measurable lithium for spectral types of K7.0-M4.5. None of our targets have significant infrared excesses in the WISE W3 band, yielding an upper limit on warm debris disks of F < 0.7%. Finally, our purely kinematic and color-magnitude selection procedure allows us to test the efficiency and completeness for activity-based selection of young stars. We find that 60% of K-M dwarfs in Tuc-Hor do not have ROSAT counterparts and would have been omitted in X-ray-selected samples. In contrast, GALEX UV-selected samples using a previously suggested criterion for youth achieve completeness of 77% and purity of 78%, and we suggest new SpT-dependent selection criteria that will yield >95% completeness for ~ 40 Myr populations with GALEX data available.
  65. Harris, A., Pravec, P., Galad, A., Skiff, B., Warner, B., Vilagi, J., Gajdos, S., Carbognani, A., Hornoch, K., Kusnirak, P., Cooney, W., Gross, J., Terrell, D., Higgins, D., Bowell, E., Koehn, B., 2014, Icar, 235, 55, On the maximum amplitude of harmonics of an asteroid lightcurve
    Most asteroid lightcurves are dominated by the second harmonic of the rotation period, caused by elongated shape. However, if the shape is not very elongate, other harmonics may dominate, leading to ambiguity of which is the true rotation period. We argue from geometry that at low phase angle, harmonics other than the second with amplitude exceeding 0.4 magnitude are nearly impossible, so lightcurves with larger amplitude than that suggest a unique period dominated by the second harmonic, unless the spin is complex, non-principal axis rotation. On the other hand, lightcurves with amplitude less than 0.2-0.3 magnitudes can be dominated by other harmonics, especially the 4th and 6th, so the period may be ambiguous unless odd harmonics can be found to identify the true rotation period. We present examples of each, low and high amplitude ambiguities.
  66. Grundy, W., Olkin, C., Young, L., Holler, B., 2014, Icar, 235, 220, Near-infrared spectral monitoring of Pluto's ices II: Recent decline of CO and N2 ice absorptions
    IRTF/SpeX observations of Pluto's near-infrared reflectance spectrum during 2013 show vibrational absorption features of CO and N2 ices at 1.58 and 2.15 m, respectively, that are weaker than had been observed during the preceding decade. To reconcile declining volatile ice absorptions with a lack of decline in Pluto's atmospheric pressure, we suggest these ices could be getting harder to see because of increasing scattering by small CH4 crystals, rather than because they are disappearing from the observed hemisphere.
  67. Davenport, J., Ivezic, Z., Becker, A., Ruan, J., Hunt-Walker, N., Covey, K., Lewis, A., AlSayyad, Y., Anderson, L., 2014, MNRAS, 440, 3430, The SDSS-2MASS-WISE 10-dimensional stellar colour locus
    We present the fiducial main-sequence stellar locus traced by 10 photometric colours observed by Sloan Digital Sky Survey (SDSS), Two Micron All Sky Survey (2MASS), and Wide-field Infrared Survey Explorer (WISE). Median colours are determined using 1052 793 stars with r-band extinction less than 0.125. We use this locus to measure the dust extinction curve relative to the r band, which is consistent with previous measurements in the SDSS and 2MASS bands. The WISE band extinction coefficients are larger than predicted by standard extinction models. Using 13 lines of sight, we find variations in the extinction curve in H, Ks, and WISE bandpasses. Relative extinction decreases towards Galactic anticentre, in agreement with prior studies. Relative extinction increases with Galactic latitude, in contrast to previous observations. This indicates a universal mid-IR extinction law does not exist due to variations in dust grain size and chemistry with Galactocentric position. A preliminary search for outliers due to warm circumstellar dust is also presented, using stars with high signal-to-noise ratio in the W3 band. We find 199 such outliers, identified by excess emission in Ks - W3. Inspection of SDSS images for these outliers reveals a large number of contaminants due to nearby galaxies. Six sources appear to be genuine dust candidates, yielding a fraction of systems with infrared excess of 0.12 0.05 per cent.
  68. Boyajian, T., von Braun, K., van Belle, G., Farrington, C., Schaefer, G., Jones, J., White, R., McAlister, H., ten Brummelaar, T., Ridgway, S., Gies, D., Sturmann, L., Sturmann, J., Turner, N., Goldfinger, P., Vargas, N., 2014, ApJ, 787, 92, Erratum: "Stellar Diameters and Temperatures. III. Main Sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations" (2013, ApJ, 771, 40)
    No abstract found.
  69. Elmegreen, D., Elmegreen, B., Adamo, A., Aloisi, A., Andrews, J., Annibali, F., Bright, S., Calzetti, D., Cignoni, M., Evans, A., Gallagher, J., Gouliermis, D., Grebel, E., Hunter, D., Johnson, K., Kim, H., Lee, J., Sabbi, E., Smith, L., Thilker, D., Tosi, M., Ubeda, L., 2014, ApJL, 787, L15, Hierarchical Star Formation in Nearby LEGUS Galaxies
    Hierarchical structure in ultraviolet images of 12 late-type LEGUS galaxies is studied by determining the numbers and fluxes of nested regions as a function of size from ~1 to ~200 pc, and the number as a function of flux. Two starburst dwarfs, NGC 1705 and NGC 5253, have steeper number-size and flux-size distributions than the others, indicating high fractions of the projected areas filled with star formation. Nine subregions in seven galaxies have similarly steep number-size slopes, even when the whole galaxies have shallower slopes. The results suggest that hierarchically structured star-forming regions several hundred parsecs or larger represent common unit structures. Small galaxies dominated by only a few of these units tend to be starbursts. The self-similarity of young stellar structures down to parsec scales suggests that star clusters form in the densest parts of a turbulent medium that also forms loose stellar groupings on larger scales. The presence of super star clusters in two of our starburst dwarfs would follow from the observed structure if cloud and stellar subregions more readily coalesce when self-gravity in the unit cell contributes more to the total gravitational potential.
  70. Bodewits, D., Farnham, T., A'Hearn, M., Feaga, L., McKay, A., Schleicher, D., Sunshine, J., 2014, ApJ, 786, 48, The Evolving Activity of the Dynamically Young Comet C/2009 P1 (Garradd)
    We used the Ultraviolet-Optical Telescope on board Swift to observe the dynamically young comet C/2009 P1 (Garradd) from a heliocentric distance of 3.5 AU pre-perihelion until 4.0 AU outbound. At 3.5 AU pre-perihelion, comet Garradd had one of the highest dust-to-gas ratios ever observed, matched only by comet Hale-Bopp. The evolving morphology of the dust in its coma suggests an outburst that ended around 2.2 AU pre-perihelion. Comparing slit-based measurements and observations acquired with larger fields of view indicated that between 3 AU and 2 AU pre-perihelion a significant extended source started producing water in the coma. We demonstrate that this source, which could be due to icy grains, disappeared quickly around perihelion. Water production by the nucleus may be attributed to a constantly active source of at least 75 km2, estimated to be >20% of the surface. Based on our measurements, the comet lost 4 1011 kg of ice and dust during this apparition, corresponding to at most a few meters of its surface. Even though this was likely not the comet's first passage through the inner solar system, the activity of Garradd was complex and changed significantly during the time it was observed.
  71. Hoard, D., Long, K., Howell, S., Wachter, S., Brinkworth, C., Knigge, C., Drew, J., Szkody, P., Kafka, S., Belle, K., Ciardi, D., Froning, C., van Belle, G., Pretorius, M., 2014, ApJ, 786, 68, Nova-like Cataclysmic Variables in the Infrared
    Nova-like (NL) cataclysmic variables have persistently high mass transfer rates and prominent steady state accretion disks. We present an analysis of infrared observations of 12 NLs obtained from the Two Micron All Sky Survey, the Spitzer Space Telescope, and the Wide-field Infrared Survey Explorer All Sky Survey. The presence of an infrared excess at >~ 3-5 m over the expectation of a theoretical steady state accretion disk is ubiquitous in our sample. The strength of the infrared excess is not correlated with orbital period, but shows a statistically significant correlation (but shallow trend) with system inclination that might be partially (but not completely) linked to the increasing view of the cooler outer accretion disk and disk rim at higher inclinations. We discuss the possible origin of the infrared excess in terms of emission from bremsstrahlung or circumbinary dust, with either mechanism facilitated by the mass outflows (e.g., disk wind/corona, accretion stream overflow, and so on) present in NLs. Our comparison of the relative advantages and disadvantages of either mechanism for explaining the observations suggests that the situation is rather ambiguous, largely circumstantial, and in need of stricter observational constraints.
  72. van Belle, G., von Braun, K., Boyajian, T., Schaefer, G., 2014, IAUS, 293, 378, Direct Imaging of Planet Transit Events
    Exoplanet transit events are attractive targets for the ultrahigh-resolution capabilities afforded by optical interferometers. The intersection of two developments in astronomy enable direct imaging of exoplanet transits: first, improvements in sensitivity and precision of interferometric instrumentation; and second, identification of ever-brighter host stars. Efforts are underway for the first direct high-precision detection of closure phase signatures with the CHARA Array and Navy Precision Optical Interferometer. When successful, these measurements will enable recovery of the transit position angle on the sky, along with characterization of other system parameters, such as stellar radius, planet radius, and other parameters of the transit event. This technique can directly determine the planet's radius independent of any outside observations, and appears able to improve substantially upon other determinations of that radius; it will be possible to extract wavelength dependence of that radius determination, for connection to characterization of planetary atmospheric composition & structure. Additional directly observed parameters - also not dependent on transit photometry or spectroscopy - include impact parameter, transit ingress time, and transit velocity.
  73. van Belle, G., Ridgway, S., ten Brummelaar, T., 2014, ipco, 7, 2013 Interferometry Forum Report
    The 2013 Interferometry Forum was organized around a list of topics - each topic had a moderator and an archivist. Each participant in the forum had one or more assignments - this was not a meeting for passive participation. The following summaries are a slightly edited version of those notes; conclusions and recommendations are presented at the end of the document(An expanded version of the Forum Report may be found online at the IAU Commission 54 website, http://iau-c54.wikispaces.com/2013+Interferometry+Forum).
  74. Cody, A., Stauffer, J., Baglin, A., Micela, G., Rebull, L., Flaccomio, E., Morales-Calderon, M., Aigrain, S., Bouvier, J., Hillenbrand, L., Gutermuth, R., Song, I., Turner, N., Alencar, S., Zwintz, K., Plavchan, P., Carpenter, J., Findeisen, K., Carey, S., Terebey, S., Hartmann, L., Calvet, N., Teixeira, P., Vrba, F., Wolk, S., Covey, K., Poppenhaeger, K., Gunther, H., Forbrich, J., Whitney, B., Affer, L., Herbst, W., Hora, J., Barrado, D., Holtzman, J., Marchis, F., Wood, K., Medeiros Guimaraes, M., Lillo Box, J., Gillen, E., McQuillan, A., Espaillat, C., Allen, L., D'Alessio, P., Favata, F., 2014, AJ, 147, 82, CSI 2264: Simultaneous Optical and Infrared Light Curves of Young Disk-bearing Stars in NGC 2264 with CoRoT and SpitzerEvidence for Multiple Origins of Variability
    We present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30 day multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes and assess the fractional representation within each class. The largest category (>20%) are optical "dippers" with discrete fading events lasting ~1-5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with H emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk.

    Based on data from the Spitzer and CoRoT missions. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain.

  75. Stauffer, J., Cody, A., Baglin, A., Alencar, S., Rebull, L., Hillenbrand, L., Venuti, L., Turner, N., Carpenter, J., Plavchan, P., Findeisen, K., Carey, S., Terebey, S., Morales-Calderon, M., Bouvier, J., Micela, G., Flaccomio, E., Song, I., Gutermuth, R., Hartmann, L., Calvet, N., Whitney, B., Barrado, D., Vrba, F., Covey, K., Herbst, W., Furesz, G., Aigrain, S., Favata, F., 2014, AJ, 147, 83, CSI 2264: Characterizing Accretion-burst Dominated Light Curves for Young Stars in NGC 2264
    Based on more than four weeks of continuous high-cadence photometric monitoring of several hundred members of the young cluster NGC 2264 with two space telescopes, NASA's Spitzer and the CNES CoRoT (Convection, Rotation, and planetary Transits), we provide high-quality, multi-wavelength light curves for young stellar objects whose optical variability is dominated by short-duration flux bursts, which we infer are due to enhanced mass accretion rates. These light curves show many briefseveral hours to one daybrightenings at optical and near-infrared wavelengths with amplitudes generally in the range of 5%-50% of the quiescent value. Typically, a dozen or more of these bursts occur in a 30 day period. We demonstrate that stars exhibiting this type of variability have large ultraviolet (UV) excesses and dominate the portion of the u - g versus g - r color-color diagram with the largest UV excesses. These stars also have large H equivalent widths, and either centrally peaked, lumpy H emission profiles or profiles with blueshifted absorption dips associated with disk or stellar winds. Light curves of this type have been predicted for stars whose accretion is dominated by Rayleigh-Taylor instabilities at the boundary between their magnetosphere and inner circumstellar disk, or where magneto-rotational instabilities modulate the accretion rate from the inner disk. Among the stars with the largest UV excesses or largest H equivalent widths, light curves with this type of variability greatly outnumber light curves with relatively smooth sinusoidal variations associated with long-lived hot spots. We provide quantitative statistics for the average duration and strength of the accretion bursts and for the fraction of the accretion luminosity associated with these bursts.

    Based on data from the Spitzer and CoRoT missions, as well as the Canada-France-Hawaii Telescope (CFHT) MegaCam CCD, and the European Southern Observatory Very Large Telescope, Paranal Chile, under program 088.C-0239. The CoRoT space mission was developed and is operated by the French space agency CNES, with participation of ESA's RSSD and Science Programmes, Austria, Belgium, Brazil, Germany, and Spain. MegaCam is a joint project of CFHT and CEA/DAPNIA, which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.

  76. Shkolnik, E., Barman, T., 2014, ebi, 2.3, HAZMAT I: The Evolution of X-ray, Far-UV and Near-UV Emission from Early M Stars
    With the recent discoveries of several super-earths orbiting M dwarfs well within their habitable zones (0.1 to 0.4 AU), and with many more such planets to come, it is critical to assess the evolution of the high-energy radiation environment of these systems. We have begun the HAZMAT (HAbitable Zones and M dwarf Activity across Time) program by first measuring the drop in near-UV and far-UV flux in early M stars from 10 Myr to several Gyr using photometry from NASA's Galaxy Evolution Explorer (GALEX). We focus this study on the confirmed low-mass members of nearby young moving groups, the Hyades cluster, and old field stars. We show a relatively slow decline in UV flux up until at least 650 Myr with a sharper drop in the old M dwarfs. Yet without confirmed M dwarfs in nearby star clusters with ages of 1-2 Gyr, mapping the precise evolution at these older ages is not currently possible. The UV data also provide much-needed constraints to M dwarf upper-atmosphere models, which are currently insufficient for predicting UV emission from M dwarfs. Our analysis will aid empirically motivated upper-atmospheric modeling for the young and old M stars, which can then be used to predict the extreme-UV fluxes most critical to the evolution of a planetary atmosphere. (See HAZMAT II abstract by Peacock et al.) The HAZMAT program is the first comprehensive study of the UV history of M stars.
  77. Peacock, S., Barman, T., Shkolnik, E., 2014, ebi, P2.33, HAZMAT II: Modeling the Evolution of Extreme--UV Radiation from M Stars
    M dwarf stars make up nearly 75% of the Milky Way's stellar population. Due to their low luminosities, the habitable zones around these stars are very close in (~0.1--0.4 AU), which makes it easier to find terrestrial planets located in these regions. Stars emit their highest levels of extreme ultraviolet (EUV) radiation in the earliest stages of their evolution while planets are simultaneously forming and accumulating their atmospheres. High levels of EUV radiation can alter the abundance of important molecules such as H2O, changing the chemistry in extrasolar planet atmospheres. This research is the next major step in the HAZMAT (HAbitable Zones and M dwarf Activity across Time) project to analyze how the habitable zone evolves with the evolving properties of stellar and planetary atmospheres. Most previous stellar atmosphere models under--predict far ultraviolet (FUV) emission from M dwarfs; here we present new models for M stars that include prescriptions for the hot, lowest density, atmospheric layers (chromosphere, transition region and corona). By comparing our model spectra to GALEX near and far ultraviolet fluxes (see HAZMAT 1 abstract by Shkolnik et al.), we are able to predict the evolution of EUV radiation for M dwarfs from 10 Myr -- 1 Gyr. The results of the HAZMAT project will tell if a planet in the canonical habitable zone is truly habitable by understanding the evolution of planetary atmospheres as they are subject to large amounts of high--energy radiation.
  78. van Eyken, J., Ciardi, D., Barnes, J., Brown, T., Dragomir, D., Eastman, J., Beichman, C., Belle, G., Braun, K., Carey, S., Crockett, C., Fortney, J., Howell, S., Jackson, B., Johns-Krull, C., Kane, S., Lister, T., Mazin, B., McLane, J., Plavchan, P., Prato, L., Shporer, A., Stauffer, J., PTF Collaboration, 2014, ebi, P3.57, PTFO 8-8695b: An Extremely Young T-Tauri-Transiting Planet
    Estimated at only ~3Myr old, PTFO 8-8695b is a candidate for the youngest transiting planet yet found, and presents a potentially valuable snapshot of a close-in pre-main-sequence planet still in its infancy. Ongoing investigation is painting an unusual but increasingly compelling picture: orbiting a rapidly-rotating T-Tauri star at just under a half-day period, it appears the planet's orbit may be inclined and precessing on timescales as short as ~hundreds of days - a timescale easily accessible to observation. The star shows substantial flaring activity, and the planet's measured radius suggests that it may be actively be losing mass. The unusual properties of this object make it particularly interesting for continued investigation. We present some of our current observations and our interpretation of the data.
  79. von Braun, K., Boyajian, T., van Belle, G., Kane, S., Jones, J., Farrington, C., Schaefer, G., Vargas, N., Scott, N., ten Brummelaar, T., Kephart, M., Gies, D., Ciardi, D., Lopez-Morales, M., Mazingue, C., McAlister, H., Ridgway, S., Goldfinger, P., Turner, N., Sturmann, L., 2014, MNRAS, 438, 2413, Stellar diameters and temperatures - V. 11 newly characterized exoplanet host stars
    We use near-infrared interferometric data coupled with trigonometric parallax values and spectral energy distribution fitting to directly determine stellar radii, effective temperatures and luminosities for the exoplanet host stars 61 Vir, CrB, GJ 176, GJ 614, GJ 649, GJ 876, HD 1461, HD 7924, HD 33564, HD 107383 and HD 210702. Three of these targets are M dwarfs. Statistical uncertainties in the stellar radii and effective temperatures range from 0.5 to 5 per cent and from 0.2 to 2 per cent, respectively. For eight of these targets, this work presents the first directly determined values of radius and temperature; for the other three, we provide updates to their properties. The stellar fundamental parameters are used to estimate stellar mass and calculate the location and extent of each system's circumstellar habitable zone. Two of these systems have planets that spend at least parts of their respective orbits in the system habitable zone: two of GJ 876's four planets and the planet that orbits HD 33564. We find that our value for GJ 876's stellar radius is more than 20 per cent larger than previous estimates and frequently used values in the astronomical literature.
  80. Boyajian, T., van Belle, G., von Braun, K., 2014, AJ, 147, 47, Stellar Diameters and Temperatures. IV. Predicting Stellar Angular Diameters
    The number of stellar angular diameter measurements has greatly increased over the past few years due to innovations and developments in the field of long baseline optical interferometry. We use a collection of high-precision angular diameter measurements for nearby, main-sequence stars to develop empirical relations that allow the prediction of stellar angular sizes as a function of observed photometric color. These relations are presented for a combination of 48 broadband color indices. We empirically show for the first time a dependence on metallicity of these relations using Johnson (B - V) and Sloan (g - r) colors. Our relations are capable of predicting diameters with a random error of less than 5% and represent the most robust and empirical determinations of stellar angular sizes to date.
  81. Benecchi, S., Noll, K., Thirouin, A., Ryan, E., Grundy, W., Verbiscer, A., Doressoundiram, A., Hestroffer, D., Beaton, R., Rabinowitz, D., Chanover, N., 2014, Icar, 229, 423, The UT 7/8 February 2013 Sila-Nunam mutual event & future predictions
    A superior mutual event of the Kuiper Belt binary system (79360) Sila-Nunam was observed over 15.47 h on UT 7/8 February 2013 by a coordinated effort at four different telescope facilities; it started 1.5 h earlier than anticipated, the duration was 9.5 h (about 10% longer than predicted), and was slightly less deep than predicted. It is the first full event observed for a comparably sized binary Kuiper Belt object. We provide predictions for future events refined by this and other partial mutual event observations obtained since the mutual event season began.
  82. Bonnefoy, M., Currie, T., Marleau, G., Schlieder, J., Wisniewski, J., Carson, J., Covey, K., Henning, T., Biller, B., Hinz, P., Klahr, H., Marsh Boyer, A., Zimmerman, N., Janson, M., McElwain, M., Mordasini, C., Skemer, A., Bailey, V., Defrere, D., Thalmann, C., Skrutskie, M., Allard, F., Homeier, D., Tamura, M., Feldt, M., Cumming, A., Grady, C., Brandner, W., Helling, C., Witte, S., Hauschildt, P., Kandori, R., Kuzuhara, M., Fukagawa, M., Kwon, J., Kudo, T., Hashimoto, J., Kusakabe, N., Abe, L., Brandt, T., Egner, S., Guyon, O., Hayano, Y., Hayashi, M., Hayashi, S., Hodapp, K., Ishii, M., Iye, M., Knapp, G., Matsuo, T., Mede, K., Miyama, M., Morino, J., Moro-Martin, A., Nishimura, T., Pyo, T., Serabyn, E., Suenaga, T., Suto, H., Suzuki, R., Takahashi, Takami, M., Takato, N., Terada, H., Tomono, D., Turner, E., Watanabe, M., Yamada, T., Takami, H., Usuda, T., 2014, A&A, 562, A111, Characterization of the gaseous companion Andromedae b. New Keck and LBTI high-contrast observations
    Context. We previously reported the direct detection of a low-mass companion at a projected separation of 55 2 AU around the B9-type star Andromedae. The properties of the system (mass ratio, separation) make it a benchmark for understanding the formation and evolution of gas giant planets and brown dwarfs on wide orbits.
    Aims: We present new angular differential imaging (ADI) images of the system at 2.146 (Ks), 3.776 (L'), 4.052 (NB_4.05), and 4.78 m (M') obtained with Keck/NIRC2 and LBTI/LMIRCam, as well as more accurate near-infrared photometry of the star with the MIMIR instrument. We aim to determine the near-infrared spectral energy distribution of the companion and use it to characterize the object.
    Methods: We used analysis methods adapted to ADI to extract the companion flux. We compared the photometry of the object to reference young, and old objects and to a set of seven PHOENIX-based atmospheric models of cool objects accounting for the formation of dust. We used evolutionary models to derive mass estimates considering a wide range of plausible initial conditions. Finally, we used dedicated formation models to discuss the possible origin of the companion.
    Results: We derive a more accurate J = 15.86 0.21, H = 14.95 0.13, Ks = 14.32 0.09 mag for And b. We detect the companion in all our high-contrast observations. We confirm previous contrasts obtained at Ks and L' band. We derive NB_4.05 = 13.0 0.2, and M' = 13.3 0.3 mag and estimate log 10(L/L) = -3.76 0.06. Atmospheric models yield Teff = 1900+100-200 K. They do not set any constraint on the surface gravity. "Hot-start" evolutionary models predict masses of 14+25-2 MJup based on the luminosity and temperature estimates, and when considering a conservative age range for the system (30+120-10 Myr), "warm-start" evolutionary tracks constrain the mass to M 10MJup.
    Conclusions: The mass of Andromedae b mostly falls in the brown-dwarf regime, owing to remaining uncertainties in age and in mass-luminosity models. According to the formation models, disk instability in a primordial disk may account for the position and a wide range of plausible masses of And b.

    The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Instituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of the University of Notre Dame, University of Minnesota, and University of Virginia.Appendices are available in electronic form at http://www.aanda.org

  83. Knight, M., Battams, K., 2014, ApJL, 782, L37, Preliminary Analysis of SOHO/STEREO Observations of Sungrazing Comet ISON (C/2012 S1) around Perihelion
    We present photometric and morphological analysis of the behavior of sungrazing comet C/2012 S1 ISON in Solar and Heliospheric Observatory (SOHO) and Solar TErrestrial RElations Observatory (STEREO) images around its perihelion on 2013 November 28.779 UT. ISON brightened gradually November 20-26 with a superimposed outburst on November 21.3-23.5. The slope of brightening changed about November 26.7 and was significantly steeper in SOHO's orange and clear filter images until November 27.9 when it began to flatten out, reaching a peak about November 28.1 (r H 17 R ), then fading before brightening again from November 28.6 (r H 5 R ) until disappearing behind the occulting disk. ISON brightened continuously as it approached perihelion while visible in all other telescopes/filters. The central condensation disappeared about November 28.5 and the leading edge became progressively more elongated until perihelion. These photometric and morphological behaviors are reminiscent of the tens of meter-sized Kreutz comets regularly observed by SOHO and STEREO and strongly suggest that the nucleus of ISON was destroyed prior to perihelion. This is much too small to support published gas production rates and implies significant mass loss and/or disruption in the days and weeks leading up to perihelion. No central condensation was seen post-perihelion. The post-perihelion lightcurve was nearly identical in all telescopes/filters and fell slightly steeper than r_{H}^{-2}. This implies that the brightness was dominated by reflected solar continuum off of remnant dust in the coma/tail and that any remaining active nucleus was <10 m in radius.
  84. Caballero-Nieves, S., Nelan, E., Gies, D., Wallace, D., DeGioia-Eastwood, K., Herrero, A., Jao, W., Mason, B., Massey, P., Moffat, A., Walborn, N., 2014, AJ, 147, 40, A High Angular Resolution Survey of Massive Stars in Cygnus OB2: Results from the Hubble Space Telescope Fine Guidance Sensors
    We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the fine guidance sensor 1R (FGS1r) on the Hubble Space Telescope. FGS1r is able to resolve binary systems with a magnitude difference V < 4 down to separations as small as 0.''01. The sample includes 58 of the brighter members of Cyg OB2, one of the closest examples of an environment containing a large number of very young and massive stars. We resolved binary companions for 12 targets and confirmed the triple nature of one other target, and we offer evidence of marginally resolved companions for two additional stars. We confirm the binary nature of 11 of these systems from complementary adaptive optics imaging observations. The overall binary frequency in our study is 22% to 26% corresponding to orbital periods ranging from 20 to 20,000 yr. When combined with the known short-period spectroscopic binaries, the results support the hypothesis that the binary fraction among massive stars is >60%. One of the new discoveries is a companion to the hypergiant star MT 304 = Cyg OB2-12, and future measurements of orbital motion should provide mass estimates for this very luminous star.
  85. Baines, E., Armstrong, J., Schmitt, H., Benson, J., Zavala, R., van Belle, G., 2014, ApJ, 781, 90, Navy Precision Optical Interferometer Measurements of 10 Stellar Oscillators
    Using the Navy Precision Optical Interferometer, we measured the angular diameters of 10 stars that have previously measured solar-like oscillations. Our sample covered a range of evolutionary stages but focused on evolved subgiant and giant stars. We combined our angular diameters with Hipparcos parallaxes to determine the stars' physical radii, and used photometry from the literature to calculate their bolometric fluxes, luminosities, and effective temperatures. We then used our results to test the scaling relations used by asteroseismology groups to calculate radii and found good agreement between the radii measured here and the radii predicted by stellar oscillation studies. The precision of the relations is not as well constrained for giant stars as it is for less evolved stars.
  86. Clark, R., Swayze, G., Carlson, R., Grundy, W., Noll, K., 2014, RMGeo, 78, 399, Spectroscopy from Space
    This chapter reviews detection of materials on solid and liquid (lakes and ocean) surfaces in the solar system using ultraviolet to infrared spectroscopy from space, or near space (high altitude aircraft on the Earth), or in the case of remote objects, earth-based and earth-orbiting telescopes. Point spectrometers and imaging spectrometers have been probing the surfaces of our solar system for decades. Spacecraft carrying imaging spectrometers are currently in orbit around Mercury, Venus, Earth, Mars, and Saturn, and systems have recently visited Jupiter, comets, asteroids, and one spectrometer-carrying spacecraft is on its way to Pluto. Together these systems are providing a wealth of data that will enable a better understanding of the composition of condensed matter bodies in the solar system.

    Minerals, ices, liquids, and other materials have been detected and mapped on the Earth and all planets and/or their satellites where the surface can be observed from space, with the exception of Venus whose thick atmosphere limits surface observation. Basaltic minerals (e.g., pyroxene and olivine) have been detected with spectroscopy on the Earth, Moon, Mars and some asteroids. The greatest mineralogic diversity seen from space is observed on the Earth and Mars. The Earth, with oceans, active tectonic and hydrologic cycles, and biological processes, displays the greatest material diversity including the detection of amorphous and crystalline inorganic materials, organic compounds, water and water ice.

    Water ice is a very common mineral throughout the Solar System and has been unambiguously detected or inferred in every planet and/or their moon(s) where good spectroscopic data has been obtained.

    In addition to water ice, other molecular solids have been observed in the solar system using spectroscopic methods. Solid carbon dioxide is found on all systems beyond the Earth except Pluto, although CO2 sometimes appears to be trapped in other solids rather than as an ice on some objects. The largest deposits of carbon dioxide ice are found on Mars. Sulfur dioxide ice is found in the Jupiter system. Nitrogen and methane ices are common beyond the Uranian system.

    Saturn's moon Titan probably has the most complex active extra-terrestrial surface chemistry involving organic compounds. Some of the observed or inferred compounds include ices of benzene (C6H6), cyanoacetylene (HC3N), toluene (C7H8), cyanogen (C2N2), acetonitrile (CH3CN), water (H2O), carbon dioxide (CO2), and ammonia (NH3). Confirming compounds on Titan is hampered by its thick smoggy atmosphere, where in relative terms the atmospheric interferences that hamper surface characterization lie between that of Venus and Earth.

    In this chapter we exclude discussion of the planets Jupiter, Saturn, Uranus, and Neptune because their thick atmospheres preclude observing the surface, even if surfaces exist. However, we do discuss spectroscopic observations on a number of the extra-terrestrial satellite bodies. Ammonia was predicted on many icy moons but is notably absent among the definitively detected ices with possible exceptions on Charon and possible trace amounts on some of the Saturnian satellites. Comets, storehouses of many compounds that could exist as ices in their nuclei, have only had small amounts of water ice definitively detected on their surfaces from spectroscopy. Only two asteroids have had a direct detection of surface water ice, although its presence can be inferred in others.

  87. Price-Whelan, A., Agueros, M., Fournier, A., Street, R., Ofek, E., Covey, K., Levitan, D., Laher, R., Sesar, B., Surace, J., 2014, ApJ, 781, 35, Statistical Searches for Microlensing Events in Large, Non-uniformly Sampled Time-Domain Surveys: A Test Using Palomar Transient Factory Data
    Many photometric time-domain surveys are driven by specific goals, such as searches for supernovae or transiting exoplanets, which set the cadence with which fields are re-imaged. In the case of the Palomar Transient Factory (PTF), several sub-surveys are conducted in parallel, leading to non-uniform sampling over its ~20,000 deg2 footprint. While the median 7.26 deg2 PTF field has been imaged ~40 times in the R band, ~2300 deg2 have been observed >100 times. We use PTF data to study the trade off between searching for microlensing events in a survey whose footprint is much larger than that of typical microlensing searches, but with far-from-optimal time sampling. To examine the probability that microlensing events can be recovered in these data, we test statistics used on uniformly sampled data to identify variables and transients. We find that the von Neumann ratio performs best for identifying simulated microlensing events in our data. We develop a selection method using this statistic and apply it to data from fields with >10 R-band observations, 1.1 109 light curves, uncovering three candidate microlensing events. We lack simultaneous, multi-color photometry to confirm these as microlensing events. However, their number is consistent with predictions for the event rate in the PTF footprint over the survey's three years of operations, as estimated from near-field microlensing models. This work can help constrain all-sky event rate predictions and tests microlensing signal recovery in large data sets, which will be useful to future time-domain surveys, such as that planned with the Large Synoptic Survey Telescope.
  88. Bowell, E., Oszkiewicz, D., Wasserman, L., Muinonen, K., Penttila, A., Trilling, D., 2014, M&PS, 49, 95, Asteroid spin-axis longitudes from the Lowell Observatory database
    By analyzing brightness variation with ecliptic longitude and using the Lowell Observatory photometric database, we estimate spin-axis longitudes for more than 350,000 asteroids. Hitherto, spin-axis longitude estimates have been made for fewer than 200 asteroids. We investigate longitude distributions in different dynamical groups and asteroid families. We show that asteroid spin-axis longitudes are not isotropically distributed as previously considered. We find that the spin-axis longitude distribution for Main Belt asteroids is clearly nonrandom, with an excess of longitudes from the interval 30-110 and a paucity between 120 and 180. The explanation of the nonisotropic distribution is unknown at this point. Further studies have to be conducted to determine if the shape of the distribution can be explained by observational bias, selection effects, a real physical process, or other mechanism.
  89. Le Bouquin, J., Monin, J., Berger, J., Prato, L., Benisty, M., Schaefer, G., 2014, A&A, 561, A101, Refined masses and distance of the young binary Haro 1-14 C

    Aims: We aim to refine the dynamical masses of the individual component of the low-mass pre-main sequence binary Haro 1-14C.
    Methods: We combine the data of the preliminary orbit presented previously with new interferometric observations obtained with the four 8 m telescopes of the Very Large Telescope Interferometer.
    Results: The derived masses are Ma = 0.905 0.043 M and Mb = 0.308 0.011 M for the primary and secondary components, respectively. This is about five times better than the uncertainties of the preliminary orbit. Moreover, the possibility of larger masses is now securely discarded. The new dynamical distance, d = 96 9 pc, is smaller than the distance to the Ophiuchus core with a significance of 2.6. Fitting the spectral energy distribution yields apparent diameters of a = 0.13 0.01 mas and b = 0.10 0.01 mas (corresponding to Ra = 1.50 R and Rb = 1.13 R) and a visual extinction of Av 1.75. Although the revised orbit has a nearly edge-on geometry, the system is unlikely to be a long-period eclipsing binary.
    Conclusions: The secondary in Haro 1-14C is one of the few low-mass, pre-main sequence stars with an accurately determined dynamical mass and distance.

    Based on observations collected under program 091.C-0093(A) with the PIONIER/VLTI instrument at the European Southern Observatory, Paranal, Chile.

  90. Konopacky, Q., Barman, T., Macintosh, B., Marois, C., 2014, IAUS, 299, 297, Carbon and Oxygen in the Spectrum of HR 8799c
    The field of exoplanet spectroscopy has grown tremendously in the last decade. With the discovery of gas giant planets at wide separations from their host stars via direct imaging, it is now possible to obtain exoplanet spectra with unprecedented spectral resolution. We present a medium resolution spectrum of the directly imaged exoplanet HR 8799c. This K-band spectrum was obtained using the integral field spectrograph OSIRIS on the Keck II telescope. Our spectrum shows numerous, well-resolved molecular lines from water and carbon monoxide (CO). There is no clear evidence for methane absorption, in spite of a best fit temperature of ~1100 K. We find a best fit surface gravity log(g) ~ 4.0, consistent with the inferred young age for the system (~30 Myr), and a continuum morphology consistent with previously-inferred dust clouds. Using the water and CO lines, we are able to estimate the C/O ratio for this planet. We find a ratio slightly higher than stellar (~0.65), which provides hints about the planet's formation.
  91. Newton, E., Charbonneau, D., Irwin, J., Berta-Thompson, Z., Rojas-Ayala, B., Covey, K., Lloyd, J., 2014, AJ, 147, 20, Near-infrared Metallicities, Radial Velocities, and Spectral Types for 447 Nearby M Dwarfs
    We present metallicities, radial velocities, and near-infrared (NIR) spectral types for 447 M dwarfs determined from moderate resolution (R 2000) NIR spectra obtained with the NASA Infrared Telescope Facility (IRTF)/SpeX. These M dwarfs are primarily targets of the MEarth Survey, a transiting planet survey searching for super Earths around mid-to-late M dwarfs within 33 pc. We present NIR spectral types for each star and new spectral templates for the IRTF in the Y, J, H, and K-bands, created using M dwarfs with near-solar metallicities. We developed two spectroscopic distance calibrations that use NIR spectral type or an index based on the curvature of the K-band continuum. Our distance calibration has a scatter of 14%. We searched 27 NIR spectral lines and 10 spectral indices for metallicity sensitive features, taking into account correlated noise in our estimates of the errors on these parameters. We calibrated our relation using 36 M dwarfs in common proper pairs with an F-, G-, or K-type star of known metallicity. We validated the physical association of these pairs using proper motions, radial velocities, and spectroscopic distance estimates. Our resulting metallicity calibration uses the sodium doublet at 2.2 m as the sole indicator for metallicity. It has an accuracy of 0.12 dex inferred from the scatter between the metallicities of the primaries and the estimated metallicities of the secondaries. Our relation is valid for NIR spectral types from M1V to M5V and for -1.0 dex < [Fe/H] < +0.35 dex. We present a new color-color metallicity relation using J - H and J - K colors that directly relates two observables: the distance from the M dwarf main sequence and equivalent width of the sodium line at 2.2 m. We used radial velocities of M dwarf binaries, observations at different epochs, and comparison between our measurements and precisely measured radial velocities to demonstrate a 4 km s-1 accuracy.
  92. Feaga, L., A'Hearn, M., Farnham, T., Bodewits, D., Sunshine, J., Gersch, A., Protopapa, S., Yang, B., Drahus, M., Schleicher, D., 2014, AJ, 147, 24, Uncorrelated Volatile Behavior during the 2011 Apparition of Comet C/2009 P1 Garradd
    The High Resolution Instrument Infrared Spectrometer (HRI-IR) on board the Deep Impact Flyby spacecraft detected H2O, CO2, and CO in the coma of the dynamically young Oort Cloud comet C/2009 P1 (Garradd) post-perihelion at a heliocentric distance of 2 AU. Production rates were derived for the parent volatiles, Q H2O = 4.6 0.8 1028, Q CO2 = 3.9 0.7 1027, and Q CO = 2.9 0.8 1028 molecules s-1, and are consistent with the trends seen by other observers and within the error bars of measurements acquired during a similar time period. When compiled with other observations of Garradd's dominant volatiles, unexpected behavior was seen in the release of CO. Garradd's H2O outgassing, increasing and peaking pre-perihelion and then steadily decreasing, is more typical than that of CO, which monotonically increased throughout the entire apparition. Due to the temporal asymmetry in volatile release, Garradd exhibited the highest CO to H2O abundance ratio ever observed for any comet inside the water snow line at ~60% during the HRI-IR observations. Also, the HRI-IR made the only direct measurement of CO2, giving a typical cometary abundance ratio of CO2 to H2O of 8% but, with only one measurement, no sense of how it varied with orbital position.
  93. Hines, D., Videen, G., Zubko, E., Muinonen, K., Shkuratov, Y., Kaydash, V., Knight, M., Sitko, M., Lisse, C., Mutchler, M., Hammer, D., Yanamandra-Fisher, P., 2014, ApJL, 780, L32, Hubble Space Telescope Pre-perihelion ACS/WFC Imaging Polarimetry of Comet Ison (c/2012 s1) at 3.81 AU
    We present polarization images of Comet ISON (C/2012 S1) taken with the Hubble Space Telescope (HST) on UTC 2013 May 8 (r h = 3.81 AU, = 4.34 AU), when the phase angle was 12.16. This phase angle is approximately centered in the negative polarization branch for cometary dust. The region beyond 1000 km (~0.32 arcsec 6 pixels) from the nucleus shows a negative polarization amplitude of p% ~ -1.6%. Within 1000 km of the nucleus, the polarization position angle rotates to be approximately perpendicular to the scattering plane, with an amplitude p% ~ +2.5%. Such positive polarization has been observed previously as a characteristic feature of cometary jets, and we show that Comet ISON does indeed harbor a jet-like feature. These HST observations of Comet ISON represent the first visible light, imaging polarimetry with subarcsecond spatial resolution of a Nearly Isotropic Comet beyond 3.8 AU from the Sun at a small phase angle. The observations provide an early glimpse of the properties of the cometary dust preserved in this Oort-Cloud comet.
  94. Margutti, R., Milisavljevic, D., Soderberg, A., Chornock, R., Zauderer, B., Murase, K., Guidorzi, C., Sanders, N., Kuin, P., Fransson, C., Levesque, E., Chandra, P., Berger, E., Bianco, F., Brown, P., Challis, P., Chatzopoulos, E., Cheung, C., Choi, C., Chomiuk, L., Chugai, N., Contreras, C., Drout, M., Fesen, R., Foley, R., Fong, W., Friedman, A., Gall, C., Gehrels, N., Hjorth, J., Hsiao, E., Kirshner, R., Im, M., Leloudas, G., Lunnan, R., Marion, G., Martin, J., Morrell, N., Neugent, K., Omodei, N., Phillips, M., Rest, A., Silverman, J., Strader, J., Stritzinger, M., Szalai, T., Utterback, N., Vinko, J., Wheeler, J., Arnett, D., Campana, S., Chevalier, R., Ginsburg, A., Kamble, A., Roming, P., Pritchard, T., Stringfellow, G., 2014, ApJ, 780, 21, A Panchromatic View of the Restless SN 2009ip Reveals the Explosive Ejection of a Massive Star Envelope
    The double explosion of SN 2009ip in 2012 raises questions about our understanding of the late stages of massive star evolution. Here we present a comprehensive study of SN 2009ip during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from the GeV to the radio band obtained from a variety of ground-based and space facilities (including the Very Large Array, Swift, Fermi, Hubble Space Telescope, and XMM) constrain SN 2009ip to be a low energy (E ~ 1050 erg for an ejecta mass ~0.5 M ) and asymmetric explosion in a complex medium shaped by multiple eruptions of the restless progenitor star. Most of the energy is radiated as a result of the shock breaking out through a dense shell of material located at ~5 1014 cm with M ~ 0.1 M , ejected by the precursor outburst ~40 days before the major explosion. We interpret the NIR excess of emission as signature of material located further out, the origin of which has to be connected with documented mass-loss episodes in the previous years. Our modeling predicts bright neutrino emission associated with the shock break-out if the cosmic-ray energy is comparable to the radiated energy. We connect this phenomenology with the explosive ejection of the outer layers of the massive progenitor star, which later interacted with material deposited in the surroundings by previous eruptions. Future observations will reveal if the massive luminous progenitor star survived. Irrespective of whether the explosion was terminal, SN 2009ip brought to light the existence of new channels for sustained episodic mass loss, the physical origin of which has yet to be identified.
  95. Sheehan, W., 2014, bea, 163, Barnard, Edward Emerson
    No abstract found.
  96. Sheehan, W., 2014, bea, 261, Boltzmann, Ludwig Eduard
    No abstract found.
  97. Sheehan, W., Dobbins, T., 2014, bea, 309, Brenner, Leo
    No abstract found.
  98. Sheehan, W., 2014, bea, 317, Brooks, William Robert
    No abstract found.
  99. Sheehan, W., 2014, bea, 347, Burton, Charles Edward
    No abstract found.
  100. Sheehan, W., 2014, bea, 373, Carrington, Richard Christopher
    No abstract found.
  101. Sheehan, W., 2014, bea, 394, Cerulli, Vincenzo
    No abstract found.
  102. Sheehan, W., 2014, bea, 397, Challis, James
    No abstract found.
  103. Sheehan, W., 2014, bea, 480, Crew, Henry
    No abstract found.
  104. Sheehan, W., 2014, bea, 742, Fournier, Georges
    No abstract found.
  105. Sheehan, W., 2014, bea, 765, Frost, Edwin Brant
    No abstract found.
  106. Sheehan, W., 2014, bea, 960, Hind, John Russell
    No abstract found.
  107. Giclas, H., 2014, bea, 1234, Lampland, Carl Otto
    No abstract found.
  108. Sheehan, W., Dobbins, T., 2014, bea, 1242, Kozyrev, Nikolai Alexandrovich
    No abstract found.
  109. Sheehan, W., 2014, bea, 1376, Maggini, Mentore
    No abstract found.
  110. Sheehan, W., 2014, bea, 1520, Morgan, William Wilson
    No abstract found.
  111. Sheehan, W., 2014, bea, 1575, Ney, Edward Purdy
    No abstract found.
  112. Sheehan, W., 2014, bea, 1801, Ranyard, Arthur Cowper
    No abstract found.
  113. Sheehan, W., Dobbins, T., 2014, bea, 1944, Schmidt, Johann Friedrich Julius
    No abstract found.
  114. Sheehan, W., 2014, bea, 1959, Schwabe, Samuel Heinrich
    No abstract found.
  115. Giclas, H., 2014, bea, 2015, Slipher, Earl Carl
    No abstract found.
  116. Giclas, H., 2014, bea, 2016, Slipher, Vesto Melvin
    No abstract found.
  117. Sheehan, W., 2014, bea, 2111, Swift, Lewis
    No abstract found.
  118. Giclas, H., 2014, bea, 2163, Todd, David Peck
    No abstract found.
  119. Sheehan, W., 2014, bea, 2188, Tuttle, Horace Parnell
    No abstract found.
  120. Sheehan, W., 2014, bea, 2212, van de Hulst, Hendrik Christoffel
    No abstract found.
  121. Sheehan, W., Dobbins, T., 2014, bea, 2300, Webb, Thomas William
    No abstract found.
  122. Sheehan, W., 2014, bea, 83, Antoniadi, Eugene Michael
    No abstract found.

    123. 122 publications and 4262 citations in 2014.

122 publications and 4262 citations total.

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