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Research involving Lowell Observatory staff 2013
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Years: 2013 Bottom

    2013

  1. Ten Brummelaar, T., Tuthill, P., van Belle, G., 2013, JAI, 2, 1303001, Introduction
    After nearly one and a half centuries of effort, one of the most pernicious problems in observational astronomy obtaining resolved images of the stars is finally yielding to advances in modern instrumentation. The exquisite precision delivered by today's interferometric observatories is rapidly being applied to more and more branches of optical astronomy. The most capable interferometers in the Northern Hemisphere, both located in the United States are the Navy Precision Optical Interferometer (NPOI) in Arizona and the Center for High Angular Resolution Astronomy Array (CHARA) run by Georgia State University and located in California. In early 2013 these two groups held a joint meeting hosted by the Lowell Observatory in Flagstaff. All major groups working in the field were represented at this meeting and it was suggested to us by this Journal that this was an excellent opportunity to put together a special issue on interferometry. In order to be as broad as possible, those who did not attend the CHARA/NPOI meeting were also solicited to make a contribution. The result is this collection of papers representing a snap shot of the state of the art of ground based optical and near infrared interferometry.
  2. Armstrong, J., Hutter, D., Baines, E., et al., (including Hall, J., van Belle, G.), 2013, JAI, 2, 1340002, The Navy Precision Optical Interferometer (npoi): AN Update
    The Navy Precision Optical Interferometer (NPOI) has two purposes: wide angle precise astrometry and high-resolution imaging, both at visible wavelengths. It operates with up to six 12-cm diameter apertures simultaneously, with baseline lengths (distances between array elements) from 16 m to 79 m, and disperses the combined light into 16 spectral channels. It has been operational since first fringes were found in 1994; six-beam operations began in 2001. The NPOI is undergoing upgrades in numerous areas: control system and data acquisition improvements, a second beam combiner, additional array stations for both longer and shorter baselines, and supplemental delay lines to improve sky coverage for the longer baselines. Future possibilities include the installation of four fixed 1.8 m telescopes as well as up to six moveable lightweight 1.4 m telescopes. Observing programs, including programs led by outside investigators, cover a broad range of stellar astrophysics as well as observations of geostationary satellites.
  3. Horch, E., van Belle, G., Genet, R., et al., 2013, JAI, 2, 1340009, Intensity Interferometry for the 21ST Century
    Advances in detector technology and electronic timing capabilities in recent years have resulted in a new opportunity for ultra-high resolution in astronomy using intensity interferometry. We have been working with this technology and describe here the potential as we see it. Two separate opportunities exist at present: the use of Single Photon Avalanche Diode (SPAD) detectors with existing research-grade telescopes and photomultipliers coupled with light bucket telescopes. In the future, there may also be potential for space-based intensity interferometry. While intensity interferometry is not likely to replace amplitude-based interferometry, it does have certain advantages in terms of portability, use of large baselines, narrow-band imaging, and imaging in the blue. We see a new possibility for its use particularly in stellar astrophysics for these reasons.
  4. Li, J., Kelley, M., Farnham, T., et al., (including Knight, M.), 2013, AGUFM, 2013, P24A-02, Pre-perihelion characterization of Comet C/2012 S1 (ISON)
    Comet C/2012 S1 (ISON) is a dynamically new comet on a sungrazing orbit. As such, C/ISON represents a unique opportunity to study both the cosmic-ray-irradiated surface, produced during the comet's long residence in the Oort cloud, and much deeper layers in the nucleus, exposed when the comet passes within 2 solar radii of the Sun at perihelion. During the first phase of our investigation, we collected broadband images of C/ISON on April 10, 2012 at a heliocentric distance of 4.15 AU, using the Hubble Space Telescope WFC3/UVIS. We used the F606W and F438W filters in three HST orbits covering a total span of ~19 hrs. The comet shows a well delineated coma in the sunward direction extending about 2" from the nucleus, and a dust tail at least 25" long. The coma has an average red color of 5%/0.1 micron within 1.6" from the nucleus, becoming redder towards the tail. Both the color and the size of the coma in the sunward direction are consistent with outflow of micron sized dust. Broadband photometry yielded Af of 1376 cm at 589 nm, and 1281 cm at 433 nm, measured with a 1.6" radius aperture. The total brightness of the comet within a 0.12" radius aperture remained unchanged within 0.03 mag for the entire duration of the observations. A well defined sunward jet is visible after removing the 1/ brightness distribution. The jet is centered at position angle 290 deg (E of Celestial N), with a cone angle of 45 deg, a projected length of 1.6", and a slight curvature towards the north near the end. No temporal change in the morphology is observed, suggesting the jet is circumpolar. Under this assumption, the jet's apparent position constrains the rotational pole to lie within 30 deg of (RA, Dec) = (330, 0), and an obliquity of 50-80 deg. Preliminary analysis using a coma-nucleus separation technique suggests a nuclear radius less than 2 km. The survival of such a small nucleus during its perihelion at 2.7 solar radii is certainly questionable.
  5. Hines, D., Videen, G., Zubko, E., et al., (including Knight, M.), 2013, AGUFM, 2013, P24A-03, Hubble Space Telescope ACS/WFC Imaging Polarimetry of Comet ISON (C/2012 S1) (Invited)
    We present the first polarization images of Comet ISON (C/2012 S1) taken with the Hubble Space Telescope (HST) on UTC 2013 May 8 (r = 3.81 AU, Delta = 4.34 AU), when the phase angle was = 12.25 degrees. Although this phase angle is approximately centered in the negative polarization branch for cometary dust, there is no evidence of a negative polarization circumnucleus halo region that has been observed in previous polarimetric images of short-period comets. Instead, the central region (~ 0.32 arcseconds = 6 pixels 1000 km) of the image shows a polarization amplitude p% = 2.0 - 2.5%, and a polarization direction that is approximately perpendicular to the scattering plane. Such positive polarization has been observed previously as a characteristic feature of cometary jets. The region beyond 1000 km, with sufficient signal-to-noise to make a polarization measurement ( 5000 km), shows a negative polarization amplitude p% ~ -1.8% that varies only slightly. Our results provide the first polarimetric observations of such a distant NIC at a small phase angle with sub-arcsecond spatial resolution
  6. Lisse, C., Vervack, R., Weaver, H., et al., (including Knight, M.), 2013, AGUFM, 2013, P24A-04, Observing Comet C/2012 S1 (ISON) With the Spitzer Space Telescope
    In this talk we discuss the design, implementation, and reduction of observations of Comet ISON from space using the Spitzer Space Telescope on 13.00 - 23.12 Jun UT and from the ground at Lowell Observatory on Jun 11.16 UT and from APO on 14.13 Jun UT. The comet was at distance r_h = 3.34 AU from the Sun, distance _Spitzer = 3.29 AU and 17.4 deg phase from SST, and distance _Earth = 4.25 AU and 6.8 - 7.3 deg phase at the time of observation. Preliminary analyses show ISON's Spitzer coma morphology was relatively compact and simple, with a linear anti-solar dust tail > 3x10**5 km in length and a 1/p profile gas coma extending > 10**5 km from the nucleus. Afp values in an 18,200 km radius aperture of 840, 890, and 840 80 cm were found at VRI, and 650 100 cm were found at 3.6 micron. Together, the ground-based and Spitzer photometry imply near-neutral dust scattering from the visual through the infrared. An excess at 4.5 m due to emission from a neutral gas coma is clearly found both morphologically and photometrically. The gas coma total flux and spatial profile and ISON's discovery distance imply a coma dominated by the stronger CO_2 line emission at 4.67 m, but we cannot rule out a preponderance of CO emission at 4.26 m. No variability in our Spitzer photometry at the 0.03 mag level over 24 hrs was seen. We present our imagery, spectrophotometry, and lightcurves, and discuss the physical implications of these observations of the comet made well outside the water ice line.
  7. Wooden, D., Woodward, C., Harker, D., et al., (including Knight, M.), 2013, AGUFM, 2013, P24A-07, Comet C/2012 S1 (ISON): Observations of the Dust Grains from SOFIA and of the Atomic Gas from NSO Dunn and McMath-Pierce Solar Telescopes (Invited)
    Comet C/2012 S1 (ISON) is unique in that it is a dynamically new comet derived from the Oort cloud reservoir of comets with a sun-grazing orbit. Infrared (IR) and visible wavelength observing campaigns were planned on NASA's Stratospheric Observatory For Infrared Astronomy (SOFIA) and on National Solar Observatory Dunn (DST) and McMath-Pierce Solar Telescopes, respectively. We highlight our early results. SOFIA (+FORCAST [1]) mid- to far-IR images and spectroscopy (~5-35 m) of the dust in the coma of ISON are to be obtained by the ISON-SOFIA Team during a flight window 2013 Oct 21-23 UT (r_h1.18 AU). Dust characteristics, identified through the 10 m silicate emission feature and its strength [2], as well as spectral features from cometary crystalline silicates (Forsterite) at 11.05-11.2 m, and near 16, 19, 23.5, 27.5, and 33 m are compared with other Oort cloud comets that span the range of small and/or highly porous grains (e.g., C/1995 O1 (Hale-Bopp) [3,4,5] and C/2001 Q4 (NEAT) [6]) to large and/or compact grains (e.g., C/2007 N4 (Lulin) [7] and C/2006 P1 (McNaught) [8]). Measurement of the crystalline peaks in contrast to the broad 10 and 20 m amorphous silicate features yields the cometary silicate crystalline mass fraction [9], which is a benchmark for radial transport in our protoplanetary disk [10]. The central wavelength positions, relative intensities, and feature asymmetries for the crystalline peaks may constrain the shapes of the crystals [11]. Only SOFIA can look for cometary organics in the 5-8 m region. Spatially resolved measurements of atoms and simple molecules from when comet ISON is near the Sun (r_h< 0.4 AU, near Nov-20--Dec-03 UT) were proposed for by the ISON-DST Team. Comet ISON is the first comet since comet Ikeya-Seki (1965f) [12,13] suitable for studying the alkalai metals Na and K and the atoms specifically attributed to dust grains including Mg, Si, Fe, as well as Ca. DST's Horizontal Grating Spectrometer (HGS) measures 4 settings: Na I, K, C2 to sample cometary organics (along with Mg I), and [O I] as a proxy for activity from water [14] (along with Si I and Fe I). State-of-the-art instruments that will also be employed include IBIS [15], which is a Fabry-Perot spectral imaging system that concurrently measures lines of Na, K, Ca II, or Fe, and ROSA (CSUN/QUB) [16], which is a rapid imager that simultaneously monitors Ca II or CN. From McMath-Pierce, the Solar-Stellar Spectrograph also will target ISON (320-900 nm, R~21,000, r_h<0.3 AU). Assuming survival, the intent is to target ISON over r_h<0.4 AU, characteristic of prior Na detections [12,13,17,18,19]. References: [1] Adams, J.D., et al. 2012, SPIE, 8446, 16; [2] Kelley, M.S., Wooden, D.H. 2009, PSS, 57, 1133; [3] Harker et al. 2002, ApJ, 580, 579; [4] Hayward et al. 2000, ApJ, 538, 428; [5] Hadamcik, E., Levasseur-Regourd, A.C. 2003, JQSRT, 79-80, 661; [6] Wooden, D.H. 2004, ApJL, 612, L77; [7] Woodward et al. 2011, AJ, 141, 181; [8] Kelley et al. 2010, LPSC, 41, #2375; [9] Kelley, M.S. et al. 2011, AAS, 211, 560; [10] Wooden, D.H. 2008, SSRv, 138, 75; [11] Lindsay et al. 2013, ApJ, 766, 54; [12] Preston, G. W. 1967, ApJ, 147, 718; [13] Slaughter, C.D. 1969, AJ, 74, 929; [14] McKay et al. 2012, Icarus, 222, 684; [15] Cavallini, F., 2006, Solar Phys., 236, 415; [16] Jess et al., 2010, Solar Phys, 261, 363; [17] Watanabe, J-I. et al. 2003, ApJ, 585, L159; [18] Leblanc, F. et al. 2008, A&A, 482, 293; [19] Fulle, M. et al. 2013, ApJL, 771, L21
  8. Videen, G., Zubko, E., Hines, D., et al., (including Knight, M.), 2013, AGUFM, 2013, P31A-1788, Analysis of HST pre-perihelion imaging polarimetry of Comet ISON
    We analyze the first polarization images of Comet ISON (C/2012 S1) taken during the measurement campaign of the Hubble Space Telescope (HST) on UTC 2013 May 8, when the phase angle of Comet ISON was = 12.25 degrees. We model the particles in the coma using highly irregular agglomerated debris particles. Two different polarimetric features were observed in the coma. The high positive polarization measured for the region very near the nucleus places a tight constraint on these particles. Modelling suggests that these particles are small, highly absorbing particles. The intermediate negative polarization background places a very weak constraint on the remaining particles within the coma.
  9. Kiehlmann, S., Savolainen, T., Jorstad, S., et al., (including Taylor, B.), 2013, EPJWC, 61, 06003, Analyzing polarization swings in 3C 279
    Quasar 3C 279 is known to exhibit episodes of optical polarization angle rotation. We present new, well-sampled optical polarization data for 3C 279 and introduce a method to distinguish between random and deterministic electric vector position angle (EVPA) variations. We observe EVPA rotations in both directions with different amplitudes and find that the EVPA variation shows characteristics of both random and deterministic cases. Our analysis indicates that the EVPA variation is likely dominated by a random process in the low brightness state of the jet and by a deterministic process in the flaring state.
  10. Harris, H., Dahn, C., Dupuy, T., et al., (including Levine, S.), 2013, ApJ, 779, 21, The Binary White Dwarf LHS 3236
    The white dwarf LHS 3236 (WD1639+153) is shown to be a double-degenerate binary, with each component having a high mass. Astrometry at the U.S. Naval Observatory gives a parallax and distance of 30.86 0.25 pc and a tangential velocity of 98 km s-1, and reveals binary orbital motion. The orbital parameters are determined from astrometry of the photocenter over more than three orbits of the 4.0 yr period. High-resolution imaging at the Keck Observatory resolves the pair with a separation of 31 and 124 mas at two epochs. Optical and near-IR photometry give a set of possible binary components. Consistency of all data indicates that the binary is a pair of DA stars with temperatures near 8000 and 7400 K and with masses of 0.93 and 0.91 M also possible is a DA primary and a helium DC secondary with temperatures near 8800 and 6000 K and with masses of 0.98 and 0.69 M . In either case, the cooling ages of the stars are ~3 Gyr and the total ages are <4 Gyr. The combined mass of the binary (1.66-1.84 M ) is well above the Chandrasekhar limit; however, the timescale for coalescence is long.

    Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

  11. Li, J., Kelley, M., Knight, M., et al., 2013, ApJL, 779, L3, Characterizing the Dust Coma of Comet C/2012 S1 (ISON) at 4.15 AU from the Sun
    We report results from broadband visible images of comet C/2012 S1 (ISON) obtained with the Hubble Space Telescope Wide Field Camera 3 on 2013 April 10. C/ISON's coma brightness follows a 1/ (where is the projected distance from the nucleus) profile out to 5000 km, consistent with a constant speed dust outflow model. The turnaround distance in the sunward direction suggests that the dust coma is composed of sub-micron-sized particles emitted at speeds of tens of m s-1. A()f, which is commonly used to characterize the dust production rate, was 1340 and 1240 cm in the F606W and F438W filters, respectively, in apertures <1.''6 in radius. The dust colors are slightly redder than solar, with a slope of 5.0% 0.2% per 100 nm, increasing to >10% per 100 nm 10,000 km down the tail. The colors are similar to those of comet C/1995 O1 (Hale-Bopp) and other long-period comets, but somewhat bluer than typical values for short-period comets. The spatial color variations are also reminiscent of C/Hale-Bopp. A sunward jet is visible in enhanced images, curving to the north and then tailward in the outer coma. The 1.''6 long jet is centered at a position angle of 291, with an opening angle of ~45. The jet morphology remains unchanged over 19 hr of our observations, suggesting that it is near the rotational pole of the nucleus, and implying that the pole points to within 30 of (R.A., decl.) = (330, 0). This pole orientation indicates a high obliquity of 50-80.
  12. Buie, M., Grundy, W., Tholen, D., 2013, AJ, 146, 152, Astrometry and Orbits of Nix, Kerberos, and Hydra
    We present new Hubble Space Telescope observations of three of Pluto's outer moons, Nix, Kerberos, and Hydra. This work revises previously published astrometry of Nix and Hydra from 2002 to 2003. New data from a four-month span during 2007 include observations designed to better measure the positions of Nix and Hydra. A third data set from 2010 also includes data on Nix and Hydra as well as some pre-discovery observations of Kerberos. The data were fitted using numerical point-spread function (PSF) fitting techniques to get accurate positions but also to remove the extended wings of the Pluto and Charon PSFs when working on these faint satellites. The resulting astrometric data were fitted with two-body Keplerian orbits that are useful for short-term predictions of the future positions of these satellites for stellar occultation and for guiding encounter planning for the upcoming New Horizons flyby of the Pluto system. The mutual inclinations of the satellites are all within 0.2 of the plane of Charon's orbit. The periods for all continue to show that their orbits are near but distinct from integer period ratios relative to Charon. Based on our results, the period ratios are Hydra:Charon = 5.98094 0.00001, Kerberos:Charon = 5.0392 0.0003, and Nix:Charon = 3.89135 0.00001. Based on period ratios alone, there is a trend of increased distance from an integer period ratio with decreasing distance from Charon. Our analysis shows that orbital uncertainties for Nix and Hydra are now low enough to permit useful stellar occultation predictions and for New Horizons encounter planning. In 2015 July, our orbits predict a position error of 60 km for Nix and 38 km for Hydra, well below other limiting errors that affect targeting. The orbit for Kerberos, however, still needs a lot of work as its uncertainty in 2015 is quite large at 22,000 km based on these data.
  13. Raiteri, C., Villata, M., D'Ammando, F., et al., (including Taylor, B.), 2013, MNRAS, 436, 1530, The awakening of BL Lacertae: observations by Fermi, Swift and the GASP-WEBT
    Since the launch of the Fermi satellite, BL Lacertae has been moderately active at -rays and optical frequencies until 2011 May, when the source started a series of strong flares. The exceptional optical sampling achieved by the GLAST-AGILE Support Program of the Whole Earth Blazar Telescope in collaboration with the Steward Observatory allows us to perform a detailed comparison with the daily -ray observations by Fermi. Discrete correlation analysis between the optical and -ray emission reveals correlation with a time lag of 0 1 d, which suggests cospatiality of the corresponding jet emitting regions. A better definition of the time lag is hindered by the daily gaps in the sampling of the extremely fast flux variations. In general, optical flares present more structure and develop on longer time-scales than corresponding -ray flares. Observations at X-rays and at millimetre wavelengths reveal a common trend, which suggests that the region producing the mm and X-ray radiation is located downstream from the optical and -ray-emitting zone in the jet. The mean optical degree of polarization slightly decreases over the considered period and in general it is higher when the flux is lower. The optical electric vector polarization angle (EVPA) shows a preferred orientation of about 15, nearly aligned with the radio core EVPA and mean jet direction. Oscillations around it increase during the 2011-2012 outburst. We investigate the effects of a geometrical interpretation of the long-term flux variability on the polarization. A helical magnetic field model predicts an evolution of the mean polarization that is in reasonable agreement with the observations. These can be fully explained by introducing slight variations in the compression factor in a transverse shock waves model.
  14. Karnath, N., Prato, L., Wasserman, L., et al., (including Skiff, B.), 2013, AJ, 146, 149, Orbital Parameters for the Two Young Binaries VSB 111 and VSB 126
    We report orbital parameters for two low-mass, pre-main-sequence, double-lined spectroscopic binaries: VSB 111 and VSB 126. These systems were originally identified as single-lined on the basis of visible-light observations. We obtained high-resolution infrared spectra with the 10 m Keck II telescope, detected absorption lines of the secondary stars, and measured radial velocities of both components in the systems. The visible-light spectra were obtained with the 1.5 m Wyeth reflector at the Oak Ridge Observatory, the 1.5 m Tillinghast reflector at the F. L. Whipple Observatory, and the 4.5 m equivalent Multiple Mirror Telescope. The combination of our visible and infrared observations of VSB 111 leads to a period of 902.1 0.9 days, an eccentricity of 0.788 0.008, and a mass ratio of 0.52 0.05. VSB 126 has a period of 12.9244 0.0002 days, an eccentricity of 0.18 0.02, and a mass ratio of 0.29 0.02. Visible-light photometry, using the 0.8 m telescope at Lowell Observatory, provided rotation periods for the primary stars in both systems: 3.74 0.02 days for VSB 111 and 5.71 0.07 days for VSB 126. Both binaries are located in the young, active star-forming cluster NGC 2264 at a distance of ~800 pc. The difference in the center-of-mass velocities of the two systems is consistent with the radial velocity gradient seen across NGC 2264. To test the evolutionary models for accuracy and consistency, we compare the stellar properties derived from several sets of theoretical calculations for pre-main-sequence evolution with our dynamical results.
  15. Landolt, A., 2013, AJ, 146, 131, UBVRI Photometric Standard Stars around the Sky at +50 deg Declination
    U BV RI photoelectric observations have been made of 335 stars around the sky, and centered approximately at +50 deg declination. The majority of the stars fall in the magnitude range 9 < V < 16, and in the color range -0.3 < (B - V) < +1.8. Those 243 stars best suited as new broadband photometric standard stars average 12.5 measures each from data taken on 98 different nights over a period of 17 years at the Kitt Peak National and Lowell Observatories.
  16. Crossfield, I., Barman, T., Hansen, B., et al., 2013, A&A, 559, A33, Warm ice giant GJ 3470b. I. A flat transmission spectrum indicates a hazy, low-methane, and/or metal-rich atmosphere
    We report our spectroscopic investigation of the transiting ice giant GJ 3470b's atmospheric transmission, and the first results of extrasolar planet observations from the new Keck/MOSFIRE spectrograph. We measure a planet/star radius ratio of 0.0789+0.0021-0.0019 in a bandpass from 2.09-2.36 m and in six narrower bands across this wavelength range. When combined with existing broadband photometry, these measurements rule out cloud-free atmospheres in chemical equilibrium assuming either solar abundances (5.4 confidence) or a moderate level of metal enrichment (50 solar abundances, 3.8), confirming previous results that such models are not representative for cool, low-mass, externally irradiated extrasolar planets. Current measurements are consistent with a flat transmission spectrum, which suggests that the atmosphere is explained by high-altitude clouds and haze, disequilibrium chemistry, unexpected abundance patterns, or the atmosphere is extremely metal-rich (200 solar). Because GJ 3470b's low bulk density sets an upper limit on the planet's atmospheric enrichment of 300 solar, the atmospheric mean molecular weight must be 9. Thus, if the atmosphere is cloud-free its spectral features should be detectable with future observations. Transit observations at shorter wavelengths will provide the best opportunity to discriminate between plausible scenarios. We obtained optical spectroscopy with the GMOS spectrograph, but these observations exhibit large systematic uncertainties owing to thin, persistent cirrus conditions. Finally, we also provide the first detailed look at the steps necessary for well-calibrated MOSFIRE observations, and provide advice for future observations with this instrument.

    Light curves are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/559/A33

  17. Biller, B., Liu, M., Wahhaj, Z., et al., (including Shkolnik, E.), 2013, ApJ, 777, 160, The Gemini/NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars
    We report results of a direct imaging survey for giant planets around 80 members of the Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of H = 13.9 mag at 1'' in combined CH4 narrowband ADI+SDI mode and median contrasts of H = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 6 M Jup, 16.4 1.0 AU), CD-35 2722B (31 8 M Jup, 67 4 AU), HD 12894B (0.46 0.08 M , 15.7 1.0 AU), and BD+07 1919C (0.20 0.03 M , 12.5 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars.

    Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministerio da Ciencia e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina).

  18. Schleicher, D., Knight, M., Levine, S., 2013, AJ, 146, 137, The Nucleus of Comet 10P/Tempel 2 in 2013 and Consequences Regarding its Rotational State: Early Science from the Discovery Channel Telescope
    We present new lightcurve measurements of Comet 10P/Tempel 2 carried out with Lowell Observatory's Discovery Channel Telescope in early 2013 when the comet was at aphelion. These data represent some of the first science obtained with this new 4.3 m facility. With Tempel 2 having been observed to exhibit a small but ongoing spin-down in its rotation period for over two decades, our primary goals at this time were two-fold. First, to determine its current rotation period and compare it to that measured shortly after its most recent perihelion passage in 2010, and second, to disentangle the spin-down from synodic effects due to the solar day and Earth's orbital motion and to determine the sense of rotation, i.e., prograde or retrograde. At our midpoint of 2013 February 24, the observed synodic period is 8.948 0.001 hr, exactly matching the predicted prograde rotation solution based on 2010 results, and yields a sidereal period of the identical value due to the solar and Earth synodic components just canceling out during the interval of the 2013 observations. The retrograde solution is ruled out because the associated sidereal periods in 2010 and 2013 are quite different even though we know that extremely little outgassing, needed to produce torques, occurred in this interval. With a definitive sense of rotation, the specific amounts of spin-down to the sidereal period could be assessed. The nominal values imply that the rate of spin-down has decreased over time, consistent with the secular drop in water production since 1988. Our data also exhibited an unexpectedly small lightcurve amplitude which appears to be associated with viewing from a large, negative sub-Earth latitude, and a lightcurve shape deviating from a simple sinusoid implying a highly irregularly shaped nucleus.
  19. Moses, J., Line, M., Visscher, C., et al., (including Barman, T.), 2013, ApJ, 777, 34, Compositional Diversity in the Atmospheres of Hot Neptunes, with Application to GJ 436b
    Neptune-sized extrasolar planets that orbit relatively close to their host starsoften called "hot Neptunes"are common within the known population of exoplanets and planetary candidates. Similar to our own Uranus and Neptune, inefficient accretion of nebular gas is expected produce hot Neptunes whose masses are dominated by elements heavier than hydrogen and helium. At high atmospheric metallicities of 10-10,000 times solar, hot Neptunes will exhibit an interesting continuum of atmospheric compositions, ranging from more Neptune-like, H2-dominated atmospheres to more Venus-like, CO2-dominated atmospheres. We explore the predicted equilibrium and disequilibrium chemistry of generic hot Neptunes and find that the atmospheric composition varies strongly as a function of temperature and bulk atmospheric properties such as metallicity and the C/O ratio. Relatively exotic H2O, CO, CO2, and even O2-dominated atmospheres are possible for hot Neptunes. We apply our models to the case of GJ 436b, where we find that a CO-rich, CH4-poor atmosphere can be a natural consequence of a very high atmospheric metallicity. From comparisons of our results with Spitzer eclipse data for GJ 436b, we conclude that although the spectral fit from the high-metallicity forward models is not quite as good as the best fit obtained from pure retrieval methods, the atmospheric composition predicted by these forward models is more physically and chemically plausible in terms of the relative abundance of major constituents. High-metallicity atmospheres (orders of magnitude in excess of solar) should therefore be considered as a possibility for GJ 436b and other hot Neptunes.
  20. Herrmann, K., Hunter, D., Elmegreen, B., 2013, AJ, 146, 104, Surface Brightness Profiles of Dwarf Galaxies. I. Profiles and Statistics
    Radial surface brightness profiles of spiral galaxies are classified into three types: (I) single exponential, or the light falls off with one exponential to a break before falling off (II) more steeply, or (III) less steeply. Profile breaks are also found in dwarf disks, but some dwarf Type IIs are flat or increasing out to a break before falling off. Here we re-examine the stellar disk profiles of 141 dwarfs: 96 dwarf irregulars (dIms), 26 Blue Compact Dwarfs (BCDs), and 19 Magellanic-type spirals (Sms). We fit single, double, or even triple exponential profiles in up to 11 passbands: GALEX FUV and NUV, ground-based UBVJHK and H, and Spitzer 3.6 and 4.5 m. We find that more luminous galaxies have brighter centers, larger inner and outer scale lengths, and breaks at larger radii; dwarf trends with MB extend to spirals. However, the V-band break surface brightness is independent of break type, MB , and Hubble type. Dwarf Type II and III profiles fall off similarly beyond the breaks but have different interiors and IIs break ~twice as far as IIIs. Outer Type II and III scale lengths may have weak trends with wavelength, but pure Type II inner scale lengths clearly decrease from the FUV to visible bands whereas Type III inner scale lengths increase with redder bands. This suggests the influence of different star formation histories on profile type, but nonetheless the break location is approximately the same in all passbands. Dwarfs continue trends between profile and Hubble types such that later-type galaxies have more Type II but fewer Type I and III profiles than early-type spirals. BCDs and Sms are over-represented as Types III and II, respectively, compared to dIms.
  21. Grundy, W., 2013, hst, 13404, Mutual Orbits and Physical Properties of Binary Transneptunian Objects
    Intriguing patterns are evident in both the orbits of transneptunian objects and in their observable external characteristics {colors, spectral features, etc.}. Bulk physical properties are needed to make sense of these observations and exploit them to constrain conditions in the protoplanetary disk where they formed. The key to obtaining bulk properties of transneptunian objects is that a sizeable proportion of them are binaries. Binary mutual orbits provide dynamical masses that can in turn be used to compute bulk densities, and a statistical sample of binary orbits offers powerful constraints on formation mechanisms as well as subsequent evolution. This proposal seeks to continue a multi-year campaign to obtain orbits for as large of a sample of binary transneptunian objects as possible. We seek to make efficient use of HST by targeting only the systems where we can obtain a dramatic improvement in orbital knowledge from just one or two visits, and only those where the secondary is too faint to pursue with ground-based near-IR adaptive optics techniques.
  22. French, L., Stephens, R., Coley, D., et al., (including Wasserman, L.), 2013, DPS, 45, 112.13, A Troop of Trojans: Photometry of 24 Jovian Trojan Asteroids
    Because of their greater distance from the Sun, the Jovian Trojans have been less studied than main belt asteroids. Although they are numerous (nearly 6000 have well determined orbits as of July 2013), the Trojans remain mysterious in many ways. Their spectra are unlike those of any meteorites in terrestrial collections. The spectra and the low albedos of Trojans, however, bear a strong resemblance to those of cometary nuclei (Abell et al. 2005; Fornasier et al. 2007; Emery et al. 2011). The Nice Model (Morbidelli et al. 2005; 2009) predicts that the Trojans may well be objects that originated with today's Kuiper Belt Objects. The rotation of asteroids larger than ~50 km in diameter seems to be determined largely by collisions, while that of smaller bodies is shaped primarily by YORP forces and torques (Pravec et al. 2008). We are surveying the rotation properties of Trojans to see whether similar trends are present. We find an abundance of slow rotators, including the first documented tumbler among the Trojans. We present 24 new Trojan lightcurves, mostly from objects ranging from 30-50 km in diameter. We also discuss observations of five sub-20 km Trojans, whose rotation properties are consistent with cometary densities. This research was supported by National Science Foundation Grant AST-1212115, by NASA Grant NNX-08AO29G, and by an American Astronomical Society Small Research Grant.
  23. Knight, M., 2013, DPS, 45, 116.01, A Review of Historical Naked-Eye Sungrazing Comets
    With the upcoming perihelion passage of Comet ISON (C/2012 S1) in November 2013, there is considerable interest in sungrazing comets at present. However, given the infrequency with which such comets appear, there have been few systematic studies of their behavior near perihelion. Bright, sometimes even daytime-observable comets have been recorded by observers around the world for more than 2000 years. A number of authors have compiled records of possible historical sungrazing comets, e.g., Hasegawa 1979, Kronk 1999, Hasegawa & Nakano 2001, England 2002, and Strom 2002. We review this literature to estimate the frequency of arrival of naked-eye sungrazing comets and investigate if there are any trends in their behavior, such as between peak brightness and length of time a comet is observable. We will also review the modern observations of naked-eye sungrazing comets (primarily Kreutz group comets observed since 1800) to investigate the frequency of fragmentation near the Sun and the dependence of survivability on size (as inferred from brightness) and/or perihelion distance.
  24. Plavchan, P., Anglada-Escude, G., White, R., et al., (including Prato, L.), 2013, DPS, 45, 204.02, Precision Near-Infrared Radial Velocities
    We have built a single gas absorption cell for precision spectroscopic radial velocity measurements in the near-infrared. We will present radial velocity time-series from a 2.3 micron pilot survey with the CSHELL spectrograph at the NASA InfraRed Telescope Facility to detect exoplanets around red, low mass, and young stars. We will present first light data at 1.6 microns from a near-infrared fiber scrambler used in tandem with our gas cell and CSHELL at IRTF. The fiber scrambler makes use of non-circular core fibers to stabilize the illumination of the slit and echelle grating against changes in seeing, focus, guiding and other sources of systematic radial velocity noise, complementing the wavelength calibration of a gas cell.
  25. Abell, P., Moskovitz, N., Trilling, D., et al., (including Grundy, W., Roe, H.), 2013, DPS, 45, 208.30, The Mission Accessible Near-Earth Objects Survey (MANOS)
    Near-Earth objects (NEOs) are essential to understanding the origin of the Solar System. Their relatively small sizes and complex dynamical histories make them excellent laboratories for studying ongoing Solar System processes. The proximity of NEOs to Earth makes them favorable targets for space missions. In addition, knowledge of their physical properties is crucial for impact hazard assessment. However, in spite of their importance to science, exploration, and planetary defense, a representative sample of physical characteristics for sub-km NEOs does not exist. Here we present the Mission Accessible Near-Earth Objects Survey (MANOS), a multi-year survey of sub-km NEOs that will provide a large, uniform catalog of physical properties (light curves + colors + spectra + astrometry), representing a 100-fold increase over the current level of NEO knowledge within this size range. This survey will ultimately characterize more than 300 mission-accessible NEOs across the visible and near-infrared ranges using telescopes in both the northern and southern hemispheres. MANOS has been awarded 24 nights per semester for the next three years on NOAO facilities including Gemini North and South, the Kitt Peak Mayall 4m, and the SOAR 4m. Additional telescopic assets available to our team include facilities at Lowell Observatory, the University of Hawaii 2.2m, NASAs IRTF, and the Magellan 6.5m telescopes. Our focus on sub-km sizes and mission accessibility (dv < 7 km/s) is a novel approach to physical characterization studies and is possible through a regular cadence of observations designed to access newly discovered NEOs within days or weeks of first detection before they fade beyond observational limits. The resulting comprehensive catalog will inform global properties of the NEO population, advance scientific understanding of NEOs, produce essential data for robotic and spacecraft exploration, and develop a critical knowledge base to address the risk of NEO impacts. We intend to conduct this survey with complete transparency, publicly sharing our target lists and survey progress. We invite collaborative uses for these data as a way to broaden the scientific impact of this survey.
  26. Grundy, W., Olkin, C., Young, L., et al., 2013, DPS, 45, 303.01, Heterogeneous and Evolving Distributions of Pluto's Volatile Surface Ices
    We report observations of Pluto's 0.8 to 2.4 m reflectance spectrum with IRTF/SpeX on 70 nights over the 13 years from 2001 to 2013. The spectra show numerous vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH4 ice that are offset by roughly 90 from the longitude of maximum CO and N2 absorption. In addition to the diurnal/longitudinal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH4 absorption bands have deepened, while the amplitude of their diurnal variation has diminished, consistent with additional CH4 absorption by high northern latitude regions rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH4 absorptions, Pluto's CO and N2 absorptions are declining over time, suggesting more equatorial or southerly distributions of those species. The authors gratefully thank the staff of IRTF for their tremendous assistance over the dozen+ years of this project. The work was funded in part by NSF grants AST-0407214 and AST-0085614 and NASA grants NAG5-4210 and NAG5-12516.
  27. Protopapa, S., Grundy, W., Tegler, S., et al., 2013, DPS, 45, 303.03, Absorption Coefficients of the Methane-Nitrogen Binary Ice System: Implications for Pluto
    Near infrared spectroscopic measurements of Pluto display methane (CH4) ice absorption bands shifted toward shorter wavelengths compared to the central wavelengths of pure CH4 obtained in the laboratory. This shift, described by Schmitt and Quirico (1992), occurs when CH4 is dissolved at low concentrations in a matrix of solid N2, and the magnitude of the shift varies from one CH4 band to another. This is the main argument behind the modeling analysis of Plutos spectra available in literature, employing pure CH4 and CH4 diluted at low concentrations in N2. However, the nitrogen-methane binary phase diagram generated from X-ray diffraction studies by Prokhvatilov & Yantsevich (1983) indicates that at temperatures relevant to the surfaces of icy dwarf planets, like Pluto, two phases contribute to the absorptions: methane ice saturated with nitrogen and nitrogen ice saturated with methane. No optical constants are available so far for the latter component, limiting this way the knowledge of the methane-nitrogen mixing ratio across and into the surface of Pluto and other dwarf planets. New infrared absorption coefficient spectra of CH4-I diluted in -N2 and -N2 diluted in CH4-I were measured at temperatures between 40 and 90 K, in the wavelength range 0.8-2.5 m at different mixing ratios. The spectra were derived from transmission measurements of crystals grown from the liquid phase in closed cells. In particular, a systematic study of the changes in CH4:N2 mixtures spectral behavior with mixing ratio is presented for the first time, in order to understand whether the peak frequencies of the CH4-ice bands correlate with the amount of N2-ice. We report a linear trend of the blueshifts of the CH4-ice bands vs CH4 abundance. This trend varies from band to band, while it is fairly constant with temperature. These data are applied to interpret unpublished high dispersion H and K bands spectra of Pluto acquired with the NACO instrument at the ESO VLT on 27 June 2008. Acknowledgments: This work was supported in part by grant number NNX11AM53G from NASA's Outer Planets Research Program.
  28. Porter, S., Grundy, W., 2013, DPS, 45, 303.07, Ejecta Transfer within the Pluto System
    The small satellites of Pluto have sufficiently low surface gravity that micrometeorite impacts can easily produce ejecta that escapes from their surfaces. This ejecta can either escape from the Pluto system or be swept up by Pluto or its satellites. We show through n-body integrations that Charon primarily sweeps up lower velocity ejecta, while Pluto is impacted by dust that is ejected at higher velocities. The dust also impacts Pluto in different locations depending on its ejection velocity. We show that the albedo features of Pluto and Charon correspond well to the expected distribution of impacts from higher velocity small satellite ejecta.
  29. Noll, K., Ryan, E., Grundy, W., et al., 2013, DPS, 45, 304.03, Ultra-Slow Rotating Outer Main Belt and Trojan Asteroids: Search for Binaries
    Binaries are already known to exist in the Outer Main Belt, Hilda, and Trojan (OMB+) populations and appear to fall into two main categories. The first are objects like 624 Hektor, 121 Hermione, 107 Camilla, and 87 Sylvia which contain elongated/bilobed primaries with small satellites, a rapidly rotating primary, and densities greater than 1000 kg/m3. On the other hand, 617 Patroclus, 17365, and 29314 have have similar-sized components, are synchronously locked (or in contact), and have densities below 1000 kg/m3. These two classes of binaries may reflect different formation mechanisms (collision vs. primordial), differences in the origin of the planetesimals and/or their subsequent dynamical and collisional evolution. As a test, we have conducted a search for other possible binary systems in the OMB+. We targeted eight objects with periods of 56-540 hours that, if tidally locked binaries like Patroclus, would be resolvable using HST. Observations completed in June 2013 with none of the objects showing clear evidence of being binary. PSF-fitting is required to rule out partially resolved systems. A negative result for eight slow rotators places only weak constraints on the binary fraction of this population subset. When combined with other published searches of Trojans, regardless of rotation period, it appears that the binary fraction in the OMB+ population is lower than among similar sized objects in the Kuiper Belt.
  30. Durech, J., Hanus, J., Vanco, R., et al., (including Bowell, E.), 2013, DPS, 45, 304.05, New Asteroid Shape Models Derived from the Lowell Photometric Database
    Asteroid shapes and spin states can be derived from their disk-integrated sparse-in-time photometry by the lightcurve inversion method. A huge amount of sparse photometry is provided by current all-sky surveys. However, the data from surveys suffer from large random and systematic errors. Oszkiewicz et al. (2011, JQSRT 112, 1919) partly removed the systematic trends in the photometry reported to the MPC and created the so-called 'Lowell photometric database'. The database consists of re-calibrated photometry for about 500,000 asteroids, with typically hundreds of brightness measurements per object. Bowell et al. (M&PS, submitted) used this database to analyze brightness variations with ecliptic longitude and estimated spin-axis longitudes for about 350,000 asteroids. In our work, we processed data for the first 10,000 numbered asteroids with the lightcurve inversion method (Kaasalainen et al., 2001, Icarus 153,37) using an enormous computational power of Asteroids@home (http://asteroidsathome.net) - a distributed computing project built on the BOINC platform. More than 10,000 users have joined the project and their computers were used for the time-consuming search for the sidereal rotation period in the sparse data. Although the photometric accuracy of the Lowell data is low 0.2 mag), we were able to find unique models for several hundred asteroids. We will present the first results based on the statistical analysis of the sample (distribution of spin vectors, for example) and we will also discuss the relevance of our approach to Gaia, LSST, ATLAS, and other future sources of asteroid photometry with sparse sampling.
  31. Holler, B., Olkin, C., Young, L., et al., (including Grundy, W.), 2013, DPS, 45, 310.04, Longitudinal Variation of Ethane Ice on the Surface of Pluto
    Efforts are ongoing in an attempt to understand Pluto's surface composition prior to the New Horizons flyby in July 2015. One such project is our observations of Pluto with the SpeX instrument on the Infrared Telescope Facility (Grundy et al. 2013, Icarus, 223, 710-721). Since 2001, we took and reduced a total of 70 nights. The data have been roughly divided into three separate longitude bins of 120 each (0-120, 120-240, and 240-360) in an effort to find longitudinal variation in ethane ice on Pluto's surface. Following the longitude convention of Grundy et. al. (2013), the actual ranges covered are 2.8-107.3 (22 nights), 120.7-239.3 (27 nights), and 242.4-355.4 (21 nights). These divisions were chosen due to the currently accepted distribution of ices on Pluto's surface. The 0-120 section is of unknown composition; the 120-240 section is thought to be dominated by N2 and CO ices; and the 240-360 section is thought to be dominated by CH4 ice. Preliminary analysis of differences between the weighted average of each longitude bin and a synthetic Hapke spectrum suggests stronger ethane absorption in areas of CH4 concentration.
  32. Bosh, A., Person, M., Levine, S., et al., (including Dunham, E., Bright, L.), 2013, DPS, 45, 404.01, The State of Pluto's Atmosphere in 2012-2013
    We observed two stellar occultations on UT 4 May 2013 and UT 9 September 2012, with the aim of measuring Pluto's atmospheric parameters. Both of these events were a world-wide collaboration of many observers, and both occurred within one month of Pluto's stationary point. For the May 2013 occultation of an R=14.0 star, observations were attempted from several sites in Chile, Venezuela, Arizona, and Massachusetts. Positive detections were made from the DuPont 2.5-m at Las Campanas, the SMARTS 1-m at Cerro Tololo, and the 0.45-m telescope at Cerro Calan, all in Chile. For the September 2012 occultation of an R=15.2 star, observations were attempted from many sites along the east coast of the U.S., and in Arizona, New Mexico, and Texas. Successful atmosphere occultation light curves were obtained from the MONET 1.2-m at the McDonald Observatory and the FIT Ortega 0.8-m in Melbourne, Florida. From these data, we find that Pluto's atmosphere has maintained the basic parameters of the 2011 measurement (Person, et al., in press) with some small but significant structural changes. The atmospheric temperature and pressure are similar to 2011 values, while the "knee" structure at half-light has continued to evolve and has been further modified since 2011. This light curve evolution maps to changes in the temperature structure and/or haze distribution in the lower atmosphere approximately 1-2 scale heights above the surface. We will present these recent data and discuss their implications for atmospheric change on Pluto as well as extrapolations toward the New Horizons encounter in 2015. This work was supported in part by NASA Planetary Astronomy grants to MIT (NNX10AB27G) and Williams College (NNX08AO50G, NNH11ZDA001N), as well as grants from USRA (#8500-98-003) and Ames Research (#NAS2-97-01) to Lowell Observatory. The observations made at FIT were partially supported by the James and Sara Ortega Endowment.
  33. Olkin, C., Young, L., Borncamp, D., et al., (including Wasserman, L.), 2013, DPS, 45, 404.02, The May 4, 2013 Stellar Occultation by Pluto and Implications for Pluto's Atmosphere
    On May 4 2013, Pluto passed in front of a 14 star and the shadow was well observed from multiple occultation groups. This paper presents results from the three light curves observed at Las Cumbres Observatory Global Telescope Network (LCOGT) from their Cerro Tololo site. The three LCOGT telescopes have 1.0 m apertures and used identical frame-transfer cameras. The cameras currently have a 2 second readout time therefore autonomous observations were scheduled with different exposure times to give good time resolution of the event. We will present results of this occultation and compare occultation results from 1988 to 2013 with volatile transport models.
  34. Knight, M., Schleicher, D., Begun, J., et al., 2013, DPS, 45, 407.01, Sungrazing Comet Potpourri: Dust Studies of SOHO/STEREO Comets and an Update on ISON (C/2012 S1)
    The set of comets observed by SOHO and STEREO provides us with 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 23 comets observed simultaneously by the same telescope 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 Marcus 2007 (ICQ 29, 39), 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. We will also present new results of our ongoing observing campaign of dynamically new sungrazing Comet ISON (C/2012 S1) at Lowell Observatory. We imaged ISON regularly from January-June 2013 with Lowell Observatorys 4.3-m Discovery Channel Telescope and 1.1-m Hall Telescope. We observed a sunward-facing coma enhancement in R-band images in March, April, and May that is similar in orientation and extent as that reported by Li et al. 2013 (CBET 3496) with the Hubble Space Telescope. We will resume observations when ISON re-emerges from solar conjunction in September and will present first results at the meeting.
  35. Li, J., Kelley, M., Farnham, T., et al., (including Knight, M.), 2013, DPS, 45, 407.02, Early pre-perihelion characterization of Comet C/2012 S1 (ISON)
    Comet C/2012 S1 (ISON) is a dynamically new comet on a sungrazing orbit. As such, C/ISON represents a unique opportunity to study both the cosmic-ray-irradiated surface, produced during the comet's long residence in the Oort cloud, and much deeper layers in the nucleus, exposed when the comet passes 1.7 solar radii from the Sun's surface at perihelion. During the first phase of our investigation, we collected broadband images of C/ISON on April 10, 2012 at a heliocentric distance of 4.15 AU, using the Hubble Space Telescope WFC3/UVIS. We used the F606W and F438W filters in three HST orbits covering a total span of ~19 hrs. The comet shows a well delineated coma in the sunward direction extending about 2" from the nucleus, and a dust tail at least 25" long. The coma has an average red color of 5%/0.1 micron within 1.6" from the nucleus, becoming redder towards the tail. Both the color and the size of the coma in the sunward direction are consistent with outflow of micron sized dust. Broadband photometry yielded Af of 1376 cm at 589 nm, and 1281 cm at 433 nm, measured with a 1.6" radius aperture. The total brightness of the comet within a 0.12" radius aperture remained unchanged within 0.03 mag for the entire duration of the observations. A well defined sunward jet is visible after removing the 1/ brightness distribution. The jet is centered at position angle 290 deg (E of Celestial N), with a cone angle of 45 deg, a projected length of 1.6", and a slight curvature towards the north near the end. No temporal change in the morphology is observed, suggesting the jet is circumpolar. Under this assumption, the jets apparent position constrains the rotational pole to lie within 30 deg of (RA, Dec) = (330, 0), and an obliquity of 50-80 deg. Preliminary analysis using a coma-nucleus separation technique suggests a nuclear radius less than 2 km. The survival of such a small nucleus during its sungrazing perihelion is certainly questionable.
  36. A'Hearn, M., Biver, N., Bodewits, D., et al., (including Knight, M., Schleicher, D.), 2013, DPS, 45, 407.04, The Early Inbound Activity of Comet ISON (C/2012 S1)
    We have assembled a variety of data on the early behavior of comet ISON through early June 2013, including V magnitudes from the ground and from spacecraft (SWIFT, DIFlyby), upper limits on gas from the DIFlyby, Herschel, and Hubble, and ground-based detections of CO and CN. We argue that the comets activity was steadily increasing from the pre-discovery observations in 2011 through late 2012. The activity then flattened and remained constant until January 2013, at which point it started to decrease and continued decreasing until earliest June. We interpret this in the classical picture (e.g., Whipple 1978 Moon and Planets 18, 343) of a dynamically new comet from the Oort cloud having a totally irradiated crust of order 3-10 meters thick from 4.5 billion years of galactic cosmic rays outside the heliosphere. The irradiated layer is released at very large distances due to the presence of free radicals and other chemically active species. As this crust is depleted the activity decreases and in early June we are awaiting the onset of normal cometary activity, which should be detected by fall at the latest.
  37. Schleicher, D., Knight, M., Bair, A., 2013, DPS, 45, 407.05, Narrowband Observations of Comets ISON (2012 S1) and 2P/Encke: Extremes of the New and the Old
    We report on narrowband filter observations of Comets ISON (2012 S1) and 2P/Encke obtained from Lowell Observatory. Observations of dynamically new Comet ISON include the first successful gas measurements of the apparition on March 5 (r = 4.57 AU) with a CN production rate of 1.3x1024 molecules/s, implying a water production rate of 1-10x1026 molecules/s for a normal range of CN-to-OH abundance ratios. Two months later the measured CN and inferred water values were about 70% higher. During the same interval the apparent dust production more than doubled, with Af increasing from 120 cm to 270 cm. Further observations, both photometry and imaging, are scheduled for early September and early October, and the results from these will be presented. In contrast to ISON, Comet Encke is highly evolved both thermally and physically, having made hundreds of close passages by the Sun. As a result, only a small fraction of its surface remains active and almost no micron-sized dust particles are released during outgassing. This fall's apparition will be the ninth for which we will have obtained gas production rates. The existing data imply a strong secular decrease in water production but a much smaller decrease for the minor species. These and new observations will be presented and we will examine whether or not these trends continue and the possible meaning. This research is supported by NASA's Planetary Astronomy and Planetary Atmospheres Programs.
  38. Lisse, C., Vervack, R., Weaver, H., et al., (including Knight, M.), 2013, DPS, 45, 407.06, Observing Comet C/2012 S1 (ISON) With Spitzer
    In this talk we discuss the design, implementation, and reduction of observations of Comet ISON from space using the Spitzer Space Telescope on 13.00 - 13.96 Jun UT and from the ground at Lowell Observatory on Jun 11.16 UT and from APO on 14.13 Jun UT. The comet was at distance rh = 3.34 AU from the Sun, distance Spitzer = 3.29 AU and 17.4o phase from SST, and distance Earth = 4.25 AU and 6.8 - 7.3o phase at the time of observation. Preliminary analyses show ISON's Spitzer coma morphology was relatively compact and simple, with a linear anti-solar dust tail > 3x105 km in length and a 1/p profile gas coma extending > 105 km from the nucleus. Afp values in an 18,200 km radius aperture of 840, 890, and 840 80 cm were found at VRI, and 650 100 cm were found at 3.6 micron. Together, the ground-based and Spitzer photometry imply near-neutral dust scattering from the visual through the infrared. An excess at 4.5 m due to emission from a neutral gas coma is clearly found both morphologically and photometrically. The gas coma total flux and spatial profile and ISONs discovery distance imply a coma dominated by the stronger CO_2 line emission at 4.67 m, but we cannot rule out a preponderance of CO emission at 4.26 m. No variability in our Spitzer photometry at the 0.03 mag level over 24 hrs was seen. We present our imagery, spectrophotometry, and lightcurves, and discuss the physical implications of these measurements of the comet made well outside the ice line.
  39. Bodewits, D., Farnham, T., A'Hearn, M., et al., (including Schleicher, D.), 2013, DPS, 45, 407.09, The evolving activity of the Dynamically Young Comet C/2009 P1 (Garradd)
    Comet C/2009 P1 (Garradd) was a dynamically young comet that was bright and well-observable from a heliocentric distance of 3.5 AU pre-perihelion until 4.5 AU outbound. The development of its activity was observed by many different observatories and instruments, both on the ground and in space (Deep Impact, Swift, SOHO-SWAN, VLT-UVES, IRTF, and many more). Because of this observing campaign, Garradd is the first comet for which production rates of all three main volatiles (H2O, CO, and CO2) were measured during a significant part of its passage through the inner solar system. These observations provide an invaluable key to how comets work. At -3.5 AU, Garradd had one of the highest dust-to-gas ratios ever observed, matched only by Hale-Bopp. Comparing slit-based measurements and observations acquired with larger fields of view indicated that between -3 AU and -2 AU a significant extended source started producing water in the coma (Combi et al. 2013, Paganini et al. 2012, Villanueva et al. 2012). This source, likely icy grains, disappeared quickly around perihelion (Bodewits et al. in prep.). The other volatiles observed in Garradds coma indicate an even more complex story. Relative abundances measured with large apertures were lowered significantly by the extended water source, indicating that these icy grains were depleted of ices more volatile than water. Differences in the volatility of cometary ices may further explain the observed trends in the abundances of CN and CO2 (mostly observed through [OI]; Decock et al. 2013). These effects do not explain the strange behavior of CO, whose production rate increased monotonically from -2 AU to +2AU (Feaga et al. submitted, and references therein). The activity of Garradd was complex and changed significantly during the time it was observed. We will discuss how these different sublimation processes fit into our understanding of cometary activity and evolution in general.
  40. Hines, D., Videen, G., Zubko, E., et al., (including Knight, M.), 2013, DPS, 45, 413.10, Hubble Space Telescope Pre-Perihelion ACS/WFC Imaging Polarimetry of Comet ISON (C/2012 S1) at 3.81 AU
    We present the first polarization images of Comet ISON (C/2012 S1) taken with the Hubble Space Telescope (HST) on UTC 2013 May 8 (r = 3.81 AU, delta = 4.34 AU), when the phase angle was 12.25 degrees. Although this phase angle is approximately centered in the negative polarization branch, there is no evidence of a negative polarization circumnucleus halo region that has been observed in previous polarimetric images of Kuiper-belt comets. Instead, the central region 0.32 arcseconds 1000 km) of the image shows a polarization p ~ 2.0 - 2.5% that is approximately perpendicular to the scattering plane. Such positive polarization has been observed previously as a characteristic feature of cometary jets. The region beyond 1000 km, with sufficient signal-to-noise to make a polarization measurement ( 5000 km), shows a negative polarization p ~ 1.8% that varies only slightly.
  41. Lejoly, C., Samarasinha, N., Ojha, L., et al., (including Schleicher, D.), 2013, DPS, 45, 413.15, Repeatability of the Dust and Gas Morphological Structures in the Coma of Comet
    Comet 1P/Halley is the most famous comet in history and has been observed for over two millennia, making it one of the most extensively studied comets. The morphology in the coma of comet 1P/Halley originates due to the activity at the nucleus and could be used as a probe of the nuclear rotation and the activity. We will present the results from a study summarizing the evolution of coma morphology of comet 1P/Halley observed from ground between October 1985 and June 1986. The results to be presented include analysis of dust features as well as gas (CN) features in the coma and comparisons will be made between their spatial and temporal evolution. About 80 CN images and 300 continuum images from the Small Bodies Node of the NASA Planetary Data System were analyzed using image enhancement techniques that were not available n the 1980s. This enables us to see coma structure never observed before in comet 1P/Halley. Because of the comet's proximity to Earth, most of our best signal-to-noise images were taken in the March-April interval of 1986. Despite the limited coverage of preceding and following months, there is a sufficient number of images to monitor morphological evolution over many months. The initial synodic periods as a function of time used to phase the images together were extrapolated from the lightcurves of the active coma (Schleicher et al. 1990, AJ, 100, 896-912). We will present the periods of repeatability of individual coma features measured using the position angle at different spatial distances from the nucleus in adjacent cycles. Separate features appear to have slightly different periods of repeatability, perhaps depending on the corresponding source regions on the nucleus and/or projection effects. The periods of repeatability of coma morphologies will be presented as a function of time from the perihelion. These results will ultimately be used in detailed modeling of the coma morphologies of comet 1P/Halley over the 1985-1986 apparition in order to characterize the activity of the comet.

    This work is supported by NASA Planetary Atmospheres grant NNX11AD85G and C.L.'s participation at the meeting is supported by a gift to the Lunar and Planetary Laboratory at the University of Arizona.

  42. Benecchi, S., Noll, K., Thirouin, A., et al., (including Grundy, W.), 2013, DPS, 45, 511.06, The UT 8 February 2013 Sila-Nunam Mutual Event & Future Predictions
    A mutual event of the Kuiper Belt binary system (79360) Sila-Nunam was observed over 15.47 hours on UT 8 February 2013 by a coordinated effort at four telescopes: Telescopio Nationale Galileo in the Canary Islands, the du Pont telescope at Las Campanas Observatory, ARC at Apache Point Observatory and the IRTF on Mauna Kea. It is the first full event observed from start to finish for this binary system. The lightcurve is consistent with two objects of similar, but perhaps not identical, size and albedo. We will present the results from this event and predictions for future events which have been refined by this and other mutual event observations obtained since the events began.
  43. Verbiscer, A., Grundy, W., Benecchi, S., et al., 2013, DPS, 45, 511.07, High Precision Lightcurves of A Mutual Event of Transneptunian Binary (79360) Sila-Nunam From Gemini Observatory
    Cold-classical Kuiper Belt binary (79360) Sila-Nunam is in the midst of a decade-long mutual event season in which its nearly equal-sized components occult and eclipse each other as viewed from Earth (Grundy et al. 2012 Icarus 220, 74-83). On 14 February 2013 UT, the Gemini Multi-Object Spectrograph (GMOS-N) camera at Gemini Observatory on Mauna Kea, Hawai'i imaged nearly an entire inferior event in which Nunam, the smaller of the two objects, eclipsed and occulted Sila. Alternating 200-second exposures in Sloan r' and i' filters continuously during the 9.3-hour event produced lightcurves containing information about sizes, colors, shapes, and albedo patterns on the system components. This mutual event is a rare opportunity to determine physical characteristics of a surface which has likely been unaltered since the time of Solar System formation. A. Verbiscer acknowledges support from NASA Planetary Astronomy. W. Grundy acknowledges support from NSF Planetary Astronomy.
  44. Fares, R., Moutou, C., Donati, J., et al., (including Shkolnik, E.), 2013, MNRAS, 435, 1451, A small survey of the magnetic fields of planet-host stars
    Using spectropolarimetry, we investigate the large-scale magnetic topologies of stars hosting close-in exoplanets. A small survey of 10 stars has been done with the twin instruments Telescope Bernard Lyot /NARVAL and Canada-France-Hawaii Telescope/ESPaDOnS between 2006 and 2011. Each target consists of circular polarization observations covering 7-22 d. For each of the seven targets in which a magnetic field was detected, we reconstructed the magnetic field topology using Zeeman-Doppler imaging. Otherwise, a detection limit has been estimated. Three new epochs of observations of Boo are presented, which confirm magnetic polarity reversal. We estimate that the cycle period is 2 yr, but recall that a shorter period of 240 d cannot still be ruled out. The result of our survey is compared to the global picture of stellar magnetic field properties in the mass-rotation diagram. The comparison shows that these giant planet-host stars tend to have similar magnetic field topologies to stars without detected hot Jupiters. This needs to be confirmed with a larger sample of stars.
  45. Knight, M., Walsh, K., 2013, ApJL, 776, L5, Will Comet ISON (C/2012 S1) Survive Perihelion?
    On 2013 November 28 Comet ISON (C/2012 S1) will pass by the Sun with a perihelion distance of 2.7 solar radii. Understanding the possible outcomes for the comet's response to such a close passage by the Sun is important for planning observational campaigns and for inferring ISON's physical properties. We present new numerical simulations and interpret them in context with the historical track record of comet disruptions and of sungrazing comet behavior. Historical data suggest that sizes below ~200 m are susceptible to destruction by sublimation driven mass loss, while we find that for ISON's perihelion distance, densities lower than 0.1 g cm-3 are required to tidally disrupt a retrograde or non-spinning body. Such low densities are substantially below the range of the best-determined comet nucleus densities, though dynamically new comets such as ISON have few measurements of physical properties. Disruption may occur for prograde rotation at densities up to 0.7 g cm-3, with the chances of disruption increasing for lower density, faster prograde rotation, and increasing elongation of the nucleus. Given current constraints on ISON's nucleus properties and the typically determined values for these properties among all comets, we find tidal disruption to be unlikely unless other factors (e.g., spin-up via torquing) affect ISON substantially. Whether or not disruption occurs, the largest remnant must be big enough to survive subsequent mass loss due to sublimation in order for ISON to remain a viable comet well after perihelion.
  46. Nielsen, E., Liu, M., Wahhaj, Z., et al., (including Shkolnik, E.), 2013, ApJ, 776, 4, The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars
    We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (1.5-2.5 M ) conducted to date and includes the planet hosts Pic and Fomalhaut. We obtained follow-up astrometry of all candidate companions within 400 AU projected separation for stars in uncrowded fields and identified new low-mass companions to HD 1160 and HIP 79797. We have found that the previously known young brown dwarf companion to HIP 79797 is itself a tight (3 AU) binary, composed of brown dwarfs with masses 58^{+21}_{-20} M Jup and 55^{+20}_{-19} M Jup, making this system one of the rare substellar binaries in orbit around a star. Considering the contrast limits of our NICI data and the fact that we did not detect any planets, we use high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M stars can have giant planets greater than 4 M Jup between 59 and 460 AU at 95% confidence, and fewer than 10% of these stars can have a planet more massive than 10 M Jup between 38 and 650 AU. Overall, we find that large-separation giant planets are not common around B and A stars: fewer than 10% of B and A stars can have an analog to the HR 8799 b (7 M Jup, 68 AU) planet at 95% confidence. We also describe a new Bayesian technique for determining the ages of field B and A stars from photometry and theoretical isochrones. Our method produces more plausible ages for high-mass stars than previous age-dating techniques, which tend to underestimate stellar ages and their uncertainties.
  47. Hunter, D., Elmegreen, B., Rubin, V., et al., (including Ashburn, A., Wright, T.), 2013, AJ, 146, 92, Star Formation in Two Luminous Spiral Galaxies
    We examined star formation in two very luminous (MV = -22 to -23) Sc-type spiral galaxies, NGC 801 and UGC 2885, using ultra-deep H images. We combine these H images with UBV and Two-Micron All-Sky Survey JHK images and H I maps to explore the star formation characteristics of disk galaxies at high luminosity. H traces star formation in these galaxies to 4-6 disk scale lengths, but the lack of detection of H further out is likely due to the loss of Lyman continuum photons. Considering gravitational instabilities alone, we find that the gas and stars in the outer regions are marginally stable in an average sense, but considering dissipative gas and radial and azimuthal forcing, the outer regions are marginally unstable to forming spiral arms. Star formation is taking place in spiral arms, which are regions of locally higher gas densities. Furthermore, we have traced smooth exponential stellar disks over four magnitudes in V-band surface brightness and 4-6 disk scale lengths, in spite of a highly variable gravitational instability parameter. Thus, gravitational instability thresholds do not seem relevant to the stellar disk. One possibility for creating an exponential disk is that the molecular cloud densities and star formation rates have exponential profiles and this fact forces the stellar disk to build up such a profile. Another possibility is that the stellar disk is continuously adjusted to an exponential shape regardless of the star formation profile, for example, through global dynamical processes that scatter stars. However, such scattering processes are only known to operate in spiral systems, in which case they cannot explain the same dilemma of smooth exponential disks observed in dwarf irregular galaxies.
  48. Person, M., Dunham, E., Bosh, A., et al., (including Levine, S., Collins, P., Bida, T., Bright, L.), 2013, AJ, 146, 83, The 2011 June 23 Stellar Occultation by Pluto: Airborne and Ground Observations
    On 2011 June 23, stellar occultations by both Pluto (this work) and Charon (future analysis) were observed from numerous ground stations as well as the Stratospheric Observatory for Infrared Astronomy (SOFIA). This first airborne occultation observation since 1995 with the Kuiper Airborne Observatory resulted in the best occultation chords recorded for the event, in three visible wavelength bands. The data obtained from SOFIA are combined with chords obtained from the ground at the IRTF, the U.S. Naval Observatory Flagstaff Station, and Leeward Community College to give the detailed state of the Pluto-Charon system at the time of the event with a focus on Pluto's atmosphere. The data show a return to the distinct upper and lower atmospheric regions with a knee or kink in the light curve separating them as was observed in 1988, rather than the smoothly transitioning bowl-shaped light curves of recent years. The upper atmosphere is analyzed by fitting a model to all of the light curves, resulting in a half-light radius of 1288 1 km. The lower atmosphere is analyzed using two different methods to provide results under the differing assumptions of particulate haze and a strong thermal gradient as causes for the lower atmospheric diminution of flux. These results are compared with those from past occultations to provide a picture of Pluto's evolving atmosphere. Regardless of which lower atmospheric structure is assumed, results indicate that this part of the atmosphere evolves on short timescales with results changing the light curve structures between 1988 and 2006, and then reverting these changes in 2011 though at significantly higher pressures. Throughout these changes, the upper atmosphere remains remarkably stable in structure, again except for the overall pressure changes. No evidence of onset of atmospheric collapse predicted by frost migration models is seen, and the atmosphere appears to be remaining at a stable pressure level, suggesting it should persist at this full level through New Horizon's flyby in 2015.
  49. Zasowski, G., Johnson, J., Frinchaboy, P., et al., (including Covey, K.), 2013, AJ, 146, 81, Target Selection for the Apache Point Observatory Galactic Evolution Experiment (APOGEE)
    The Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution infrared spectroscopic survey spanning all Galactic environments (i.e., bulge, disk, and halo), with the principal goal of constraining dynamical and chemical evolution models of the Milky Way. APOGEE takes advantage of the reduced effects of extinction at infrared wavelengths to observe the inner Galaxy and bulge at an unprecedented level of detail. The survey's broad spatial and wavelength coverage enables users of APOGEE data to address numerous Galactic structure and stellar populations issues. In this paper we describe the APOGEE targeting scheme and document its various target classes to provide the necessary background and reference information to analyze samples of APOGEE data with awareness of the imposed selection criteria and resulting sample properties. APOGEE's primary sample consists of ~105 red giant stars, selected to minimize observational biases in age and metallicity. We present the methodology and considerations that drive the selection of this sample and evaluate the accuracy, efficiency, and caveats of the selection and sampling algorithms. We also describe additional target classes that contribute to the APOGEE sample, including numerous ancillary science programs, and we outline the targeting data that will be included in the public data releases.
  50. Potter, A., Killen, R., Reardon, K., et al., (including Bida, T.), 2013, Icar, 226, 172, Observation of neutral sodium above Mercury during the transit of November 8, 2006
    We mapped the absorption of sunlight by sodium vapor in the exosphere of Mercury during the transit of Mercury on November 8, 2006, using the IBIS Interferometric BIdimensional Spectrometer at the Dunn Solar Telescope operated by the National Solar Observatory at Sunspot, New Mexico. The measurements were reduced to line-of-sight equivalent widths for absorption at the sodium D2 line around the shadow of Mercury. The sodium absorption fell off exponentially with altitude up to about 600 km. However there were regions around north and south polar-regions where relatively uniform sodium absorptions extended above 1000 km. We corrected the 0-600 km altitude profiles for seeing blur using the measured point spread function. Analysis of the corrected altitude distributions yielded surface densities, zenith column densities, temperatures and scale heights for sodium all around the planet. Sodium absorption on the dawn side equatorial terminator was less than on the dusk side, different from previous observations of the relative absorption levels. We also determined Earthward velocities for sodium atoms, and line widths for the absorptions. Earthward velocities resulting from radiation pressure on sodium averaged 0.8 km/s, smaller than a prediction of 1.5 km/s. Most line widths were in the range of 20 mA after correction for instrumental broadening, corresponding to temperatures in the range of 1000 K.
  51. Tsang, C., Spencer, J., Lellouch, E., et al., (including Roe, H.), 2013, Icar, 226, 1177, Ios contracting atmosphere post 2011 perihelion: Further evidence for partial sublimation support on the anti-Jupiter hemisphere
    New 19 m spectroscopy of Ios SO2 atmosphere in 2012 and 2013, when combined with our earlier observations starting in 2001, provides a near-yearly record of atmospheric density in the lowest scale height, spanning almost an entire jovian year. We find that the anti-Jupiter hemisphere atmospheric density is decreasing following Jupiters 2011 perihelion passage, confirming our model (Tsang, C.C.C., Spencer, J.R., Lellouch, E., Lopez-Valverde, M.A., Richter, M.J., Greathouse, T.K., [2012]. Icarus 217, 277-296) that the anti-jovian atmosphere has a large sublimation-supported component that peaks near perihelion.
  52. Galicher, R., Marois, C., Macintosh, B., et al., (including Barman, T.), 2013, EPSC, EPSC2013-1025, International Deep Planet Survey, 317 stars to determine the wide-separated planet frequency
    Since 2000, more than 300 nearby young stars were observed for the International Deep Planet Survey with adaptive optics systems at Gemini (NIRI/NICI), Keck (Nirc2), and VLT (Naco). Massive young AF stars were included in our sample whereas they have generally been neglected in first generation surveys because the contrast and target distances are less favorable to image substellar companions. The most significant discovery of the campaign is the now well-known HR 8799 multi-planet system. This remarkable finding allows, for the first time, an estimate of the Jovians planet population at large separations (further than a few AUs) instead of deriving upper limits. During my presentation, I will present the survey showing images of multiple stars and planets. I will then propose a statistic study of the observed stars deriving constraints on the Jupiter-like planet frequency at large separations.
  53. Plavchan, P., Bottom, M., Gao, P., et al., (including Prato, L.), 2013, SPIE, 8864, 88640G, Precision near-infrared radial velocity instrumentation II: noncircular core fiber scrambler
    We have built and commissioned a prototype agitated non-circular core ber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the rst on-sky performance and modal noise tests of these novel bers in the near-infrared at H and K bands using the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We discuss the design behind our novel reverse injection of a red laser for co-alignment of star-light with the ber tip via a corneWe have built and commissioned a prototype agitated non-circular core fiber scrambler for precision spectroscopic radial velocity measurements in the near-infrared H band. We have collected the first on-sky performance and modal noise tests of these novel fibers in the near-infrared at H and K bands using the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We discuss the design behind our novel reverse injection of a red laser for co-alignment of star-light with the fiber tip via a corner cube and visible camera. We summarize the practical details involved in the construction of the fiber scrambler, and the mechanical agitation of the fiber at the telescope. We present radial velocity measurements of a bright standard star taken with and without the fiber scrambler to quantify the relative improvement in the obtainable blaze function stability, the line spread function stability, and the resulting radial velocity precision. We assess the feasibility of applying this illumination stabilization technique to the next generation of near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at Keck. Our results may also be applied in the visible for smaller core diameter fibers where Fiber modal noise is a significant factor, such as behind an adaptive optics system or on a small < 1 meter class telescope such as is being pursued by the MINERVA and LCOGT collaborations.r cube and visible camera. We summarize the practical details involved in the construction of the ber scrambler, and the mechanical agitation of the ber at the telescope. We present radial velocity measurements of a bright standard star taken with and without the ber scrambler to quantify the relative improvement in the obtainable blaze function stability, the line spread function stability, and the resulting radial velocity precision. We assess the feasibility of applying this illumination stabilization technique to the next generation of near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at Keck. Our results may also be applied in the visible for smaller core diameter bers where ber modal noise is a signi cant factor, such as behind an adaptive optics system or on a small < 1 meter class telescope such as is being pursued by the MINERVA and LCOGT collaborations.
  54. Plavchan, P., Anglada-Escude, G., White, R., et al., (including Prato, L.), 2013, SPIE, 8864, 88641J, Precision near-infrared radial velocity instrumentation I: absorption gas cells
    We have built and commissioned gas absorption cells for precision spectroscopic radial velocity measurements in the near-infrared in the H and K bands. We describe the construction and installation of three such cells filled with 13CH4, 12CH3D, and 14NH3 for the CSHELL spectrograph at the NASA Infrared Telescope Facility (IRTF). We have obtained their high-resolution laboratory Fourier Transform spectra, which can have other practical uses. We summarize the practical details involved in the construction of the three cells, and the thermal and mechanical control. In all cases, the construction of the cells is very affordable. We are carrying out a pilot survey with the 13CH4 methane gas cell on the CSHELL spectrograph at the IRTF to detect exoplanets around low mass and young stars. We discuss the current status of our survey, with the aim of photon-noise limited radial velocity precision. For adequately bright targets, we are able to probe a noise floor of 7 m/s with the gas cell with CSHELL at cassegrain focus. Our results demonstrate the feasibility of using a gas cell on the next generation of near-infrared spectrographs such as iSHELL on IRTF, iGRINS, and an upgraded NIRSPEC at Keck.
  55. Miles, J., Helton, L., Sankrit, R., et al., (including Dunham, E.), 2013, SPIE, 8867, 88670N, Capabilities, performance, and status of the SOFIA science instrument suite
    The Stratospheric Observatory for Infrared Astronomy (SOFIA) is an airborne observatory, carrying a 2.5 m telescope onboard a heavily modified Boeing 747SP aircraft. SOFIA is optimized for operation at infrared wavelengths, much of which is obscured for ground-based observatories by atmospheric water vapor. The SOFIA science instrument complement consists of seven instruments: FORCAST (Faint Object InfraRed CAmera for the SOFIA Telescope), GREAT (German Receiver for Astronomy at Terahertz Frequencies), HIPO (High-speed Imaging Photometer for Occultations), FLITECAM (First Light Infrared Test Experiment CAMera), FIFI-LS (Far-Infrared Field-Imaging Line Spectrometer), EXES (Echelon-Cross-Echelle Spectrograph), and HAWC (High-resolution Airborne Wideband Camera). FORCAST is a 5-40 m imager with grism spectroscopy, developed at Cornell University. GREAT is a heterodyne spectrometer providing high-resolution spectroscopy in several bands from 60-240 m, developed at the Max Planck Institute for Radio Astronomy. HIPO is a 0.3-1.1 m imager, developed at Lowell Observatory. FLITECAM is a 1-5 m wide-field imager with grism spectroscopy, developed at UCLA. FIFI-LS is a 42-210 m integral field imaging grating spectrometer, developed at the University of Stuttgart. EXES is a 5-28 m high-resolution spectrograph, developed at UC Davis and NASA ARC. HAWC is a 50-240 m imager, developed at the University of Chicago, and undergoing an upgrade at JPL to add polarimetry capability and substantially larger GSFC detectors. We describe the capabilities, performance, and status of each instrument, highlighting science results obtained using FORCAST, GREAT, and HIPO during SOFIA Early Science observations conducted in 2011.
  56. van Belle, G., Paladini, C., Aringer, B., et al., 2013, ApJ, 775, 45, The PTI Carbon Star Angular Size Survey: Effective Temperatures and Non-sphericity
    We report new interferometric angular diameter observations of 41 carbon stars observed with the Palomar Testbed Interferometer. Two of these stars are CH carbon stars and represent the first such measurements of this subtype. Of these, 39 have Yamashita spectral classes and are of sufficiently high quality that we can determine the dependence of effective temperature on spectral type. We find that there is a tendency for the effective temperature to increase with increasing temperature index by ~120 K per step, starting at T EFF ~= 2500 K for C3, y, although there is a large amount of scatter in this relationship. Overall, the median effective temperature of the carbon star sample is 2800 270 K and the median linear radius is 360 100 R . We also find agreement, on average within 15 K, with the T EFF determinations of Bergeat et al. and a refinement of the carbon star angular size prediction based on V & K magnitudes is presented that is good to an rms of 12%. A subsample of our stars have sufficient {u, v} coverage to permit non-spherical modeling of their photospheres, and a general tendency for detection of statistically significant departures from sphericity with increasing interferometric signal-to-noise is seen. The implications of mostand potentially allcarbon stars being non-spherical is considered in the context of surface inhomogeneities and a rotation-mass-loss connection.
  57. Sanchis-Ojeda, R., Winn, J., Marcy, G., et al., (including Horch, E.), 2013, ApJ, 775, 54, Kepler-63b: A Giant Planet in a Polar Orbit around a Young Sun-like Star
    We present the discovery and characterization of a giant planet orbiting the young Sun-like star Kepler-63 (KOI-63, m Kp = 11.6, T eff = 5576 K, M sstarf = 0.98 M ). The planet transits every 9.43 days, with apparent depth variations and brightening anomalies caused by large starspots. The planet's radius is 6.1 0.2 R , based on the transit light curve and the estimated stellar parameters. The planet's mass could not be measured with the existing radial-velocity data, due to the high level of stellar activity, but if we assume a circular orbit, then we can place a rough upper bound of 120 M (3). The host star has a high obliquity ( = 104), based on the Rossiter-McLaughlin effect and an analysis of starspot-crossing events. This result is valuable because almost all previous obliquity measurements are for stars with more massive planets and shorter-period orbits. In addition, the polar orbit of the planet combined with an analysis of spot-crossing events reveals a large and persistent polar starspot. Such spots have previously been inferred using Doppler tomography, and predicted in simulations of magnetic activity of young Sun-like stars.
  58. Bowler, B., Liu, M., Shkolnik, E., et al., 2013, ApJ, 774, 55, Planets around Low-mass Stars. III. A Young Dusty L Dwarf Companion at the Deuterium-burning Limit
    We report the discovery of an L-type companion to the young M3.5V star 2MASS J01225093-2439505 at a projected separation of 1.''45 (52 AU) as part of our adaptive optics imaging search for extrasolar giant planets around young low-mass stars. 2MASS 0122-2439 B has very red near-infrared colors similar to the HR 8799 planets and the reddest known young/dusty L dwarfs in the field. Moderate-resolution (R 3800) 1.5-2.4 m spectroscopy reveals a near-infrared spectral type of L4-L6 and an angular H-band shape, confirming its cool temperature and young age. The kinematics of 2MASS 0122-2439 AB are marginally consistent with members of the ~120 Myr AB Dor young moving group based on the photometric distance to the primary (36 4 pc) and our radial velocity measurement of 2MASS 0122-2439 A from Keck/HIRES. We adopt the AB Dor group age for the system, but the high energy emission, lack of Li I 6707 absorption, and spectral shape of 2MASS 0122-2439 B suggest a range of ~10-120 Myr is possible. The age and luminosity of 2MASS 0122-2439 B fall in a strip where "hot-start" evolutionary model mass tracks overlap as a result of deuterium burning. Several known substellar companions also fall in this region (2MASS J0103-5515 ABb, AB Pic b, And b, G196-3 B, SDSS 2249+0044 B, LP 261-75 B, HD 203030 B, and HN Peg B), but their dual-valued mass predictions have largely been unrecognized. The implied mass of 2MASS 0122-2439 B is 12-13 M Jup or 22-27 M Jup if it is an AB Dor member, or possibly as low as 11 M Jup if the wider age range is adopted. Evolutionary models predict an effective temperature for 2MASS 0122-2439 B that corresponds to spectral types near the L/T transition (1300-1500 K) for field objects. However, we find a mid-L near-infrared spectral type, indicating that 2MASS 0122-2439 B represents another case of photospheric dust being retained to cooler temperatures at low surface gravities, as seen in the spectra of young (8-30 Myr) planetary companions. Altogether, the low mass, low temperature, and red colors of 2MASS 0122-2439 B make it a bridge between warm planets like Pic b and cool, very dusty ones like HR 8799 bcde.

    Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation.

    Based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

  59. Young, L., Howell, S., Young, E., et al., (including Grundy, W.), 2013, noao, 369, Pluto's volatile distribution from speckle imaging
    Howell et al. (2012) separated Pluto and Charon with the speckle imager, DSSI, and measured their diameters. We propose to build on this work, to map the volatiles on Pluto, by taking more exposures, observing in four filters designed to measure Pluto's albedo, color, and CH_4 distribution, and observing multiple faces on Pluto. This will help us study Pluto's migrating frosts as Pluto leaves the sun, and as its summer pole becomes more directly illuminated. We compare results back to HST maps in 1994 and 2002/2003 and forward to New Horizons maps in 2015 and future ground-based maps in 2015 or beyond.
  60. van Belle, G., Ciardi, D., Howell, S., et al., 2013, noao, 433, Stellar Diameters & Surface Imaging with DSSI
    Given the combination of operating wavelength and aperture size, DSSI on Gemini is the highest angular resolution single-aperture optical instrument currently available, worldwide. We propose to push the resolutions limits of DSSI by operating in the near-UV, and leverage the resulting ~8.5mas resolution to measure the diameters of 11 nearby bright giant and supergiant stars with DSSI on Gemini-N. For the 5 larger targets in our sample (>22mas), we also expect to recover simple images with 22 to 55 effective pixels, with differential, simultaneous imaging in and out of line features being particularly sensitive to surface morphology.
  61. Bowler, B., Liu, M., Riaz, B., et al., (including Shkolnik, E.), 2013, noao, 496, Reconnaissance of Young M Dwarfs: Locating the Elusive Majority of Nearby Moving Groups
    With ages between ~8-120 Myr and distances lsim;80 pc, young moving group members make excellent targets for detailed studies of pre-main sequence evolution and exoplanet imaging surveys. We propose a multi-semester spectroscopic program to confirm our sample of ~1300 X-ray-selected active M dwarfs, about one-third of which are expected to be members of young moving groups. Our program consists of three parts: a reconnaissance phase of low-resolution spectroscopy to vet unlikely association members, radial velocity observations to confirm group membership, and deep adaptive optics imaging to study the architecture and demographics of giant planets around low-mass stars. We will also exploit our rich sample to study the evolution of chromospheric and coronal activity in low-mass stars with unprecedented precision. Altogether, this program will roughly double the population of M dwarfs in young moving groups, providing new targets for a broad range of star and planet formation studies in the near-future.
  62. Prato, L., Schaefer, G., Simon, M., 2013, noao, 506, Dynamical Young Star Masses
    Mass is a star's most important property, once composition has been established, and determines the entire life trajectory of an object. Only a couple dozen young stars have absolute dynamical mass measurements, and many of those are imprecise. We propose to observe ~17 young close visual binaries in the Taurus star forming region to advance our knowledge of young star masses. We will use NIRSPEC in high-resolution mode behind the adaptive optics system on the Keck II telescope.
  63. Jorstad, S., Marscher, A., Smith, P., et al., (including Taylor, B.), 2013, ApJ, 773, 147, A Tight Connection between Gamma-Ray Outbursts and Parsec-scale Jet Activity in the Quasar 3C 454.3
    We analyze the multi-frequency behavior of the quasar 3C 454.3 during three prominent -ray outbursts: 2009 Autumn, 2010 Spring, and 2010 Autumn. The data reveal a repeating pattern, including a triple flare structure, in the properties of each -ray outburst, which implies similar mechanism(s) and location for all three events. The multi-frequency behavior indicates that the lower frequency events are co-spatial with the -ray outbursts, although the -ray emission varies on the shortest timescales. We determine that the variability from UV to IR wavelengths during an outburst results from a single synchrotron component whose properties do not change significantly over the different outbursts. Despite a general increase in the degree of optical linear polarization during an outburst, the polarization drops significantly at the peak of the -ray event, which suggests that both shocks and turbulent processes are involved. We detect two disturbances (knots) with superluminal apparent speeds in the parsec-scale jet associated with the outbursts in 2009 Autumn and 2010 Autumn. The kinematic properties of the knots can explain the difference in amplitudes of the -ray events, while their millimeter-wave polarization is related to the optical polarization during the outbursts. We interpret the multi-frequency behavior within models involving either a system of standing conical shocks or magnetic reconnection events located in the parsec-scale millimeter-wave core of the jet. We argue that -ray outbursts with variability timescales as short as ~3 hr can occur on parsec scales if flares take place in localized regions such as turbulent cells.
  64. Wahhaj, Z., Liu, M., Nielsen, E., et al., (including Shkolnik, E.), 2013, ApJ, 773, 179, The Gemini Planet-finding Campaign: The Frequency Of Giant Planets around Debris Disk Stars
    We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a >=5 M Jup planet beyond 80 AU, and <21% of debris disk stars have a >=3 M Jup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d 2 N/dMdavpropm a , where m is planet mass and a is orbital semi-major axis (with a maximum value of a max). We find that < -0.8 and/or > 1.7. Likewise, we find that < -0.8 and/or a max < 200 AU. For the case where the planet frequency rises sharply with mass ( > 1.7), this occurs because all the planets detected to date have masses above 5 M Jup, but planets of lower mass could easily have been detected by our search. If we ignore the Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a >=3 M Jup planet beyond 10 AU, and < -0.8 and/or < -1.5. Likewise, < -0.8 and/or a max < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; our non-detections at large separations show that planets with orbital separation >40 AU and planet masses >3 M Jup do not carve the central holes in these disks.

    Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministerio da Ciencia e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnologia e Innovacion Productiva (Argentina).

  65. Simon, M., Schaefer, G., Prato, L., et al., (including Ruiz-Rodriguez, D., Karnath, N., Franz, O., Wasserman, L.), 2013, ApJ, 773, 28, Masses and Distance of the Young Binary NTTS 045251+3016
    As part of our continuing campaign to measure the masses of pre-main-sequence (PMS) stars dynamically and thus to assess the reliability of the discrepant theoretical calculations of contraction to the main sequence, we present new results for NTTS 045251+3016, a visual and double-lined spectroscopic binary in the Taurus star-forming region (SFR). We obtained new high angular resolution astrometry and high spectral resolution spectroscopy at Keck Observatory. The new data lead to a significant revision of previously published orbital parameters. In particular, we find that the masses of the primary and secondary are 0.86 0.11 and 0.55 0.05 M , respectively, smaller than previously reported, and that the system lies 158.7 3.9 pc from the sun, further than previously reported.
  66. Torres, G., Ruiz-Rodriguez, D., Badenas, M., et al., (including Prato, L., Wasserman, L.), 2013, ApJ, 773, 40, The Quadruple Pre-main-sequence System LkCa 3: Implications for Stellar Evolution Models
    We report the discovery that the pre-main-sequence (PMS) object LkCa 3 in the Taurus-Auriga star-forming region is a hierarchical quadruple system of M stars. It was previously known to be a close (~0.''5) visual pair, with one component being a moderately eccentric 12.94 day single-lined spectroscopic binary. A re-analysis of archival optical spectra complemented by new near-infrared (NIR) spectroscopy shows both visual components to be double lined; the second one has a period of 4.06 days and a circular orbit. In addition to the orbital elements, we determine optical and NIR flux ratios, effective temperatures, and projected rotational velocities for all four stars. Using existing photometric monitoring observations of the system that had previously revealed the rotational period of the primary in the longer-period binary, we also detect the rotational signal of the primary in the 4.06 day binary, which is synchronized with the orbital motion. With only the assumption of coevality, a comparison of all of these constraints with current stellar evolution models from the Dartmouth series points to an age of 1.4 Myr and a distance of 133 pc, consistent with previous estimates for the region and suggesting that the system is on the near side of the Taurus complex. Similar comparisons of the properties of LkCa 3 and the well-known quadruple PMS system GG Tau with the widely used models from the Lyon series for a mixing length parameter of ML = 1.0 strongly favor the Dartmouth models.
  67. Boyajian, T., von Braun, K., van Belle, G., et al., 2013, ApJ, 771, 40, Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations
    Based on CHARA Array measurements, we present the angular diameters of 23 nearby, main-sequence stars, ranging from spectral types A7 to K0, 5 of which are exoplanet host stars. We derive linear radii, effective temperatures, and absolute luminosities of the stars using Hipparcos parallaxes and measured bolometric fluxes. The new data are combined with previously published values to create an Angular Diameter Anthology of measured angular diameters to main-sequence stars (luminosity classes V and IV). This compilation consists of 125 stars with diameter uncertainties of less than 5%, ranging in spectral types from A to M. The large quantity of empirical data is used to derive color-temperature relations to an assortment of color indices in the Johnson (BVR J I J JHK), Cousins (R C I C), Kron (R K I K), Sloan (griz), and WISE (W 3 W 4) photometric systems. These relations have an average standard deviation of ~3% and are valid for stars with spectral types A0-M4. To derive even more accurate relations for Sun-like stars, we also determined these temperature relations omitting early-type stars (T eff > 6750 K) that may have biased luminosity estimates because of rapid rotation; for this subset the dispersion is only ~2.5%. We find effective temperatures in agreement within a couple of percent for the interferometrically characterized sample of main-sequence stars compared to those derived via the infrared flux method and spectroscopic analysis.
  68. Schaefer, G., Prato, L., Simon, M., et al., 2013, prpl, Orbital Motion in Pre-Main Sequence Binaries
    We present results from our ongoing program to map the visual orbits of pre-main sequence binaries in the Taurus star forming region using adaptive optics imaging at the Keck Observatory. Our goal is to measure precise masses of low-mass pre-main sequence stars to compare with models of stellar evolution. Thus far, we have computed definitive orbits for V807 Tau Ba-Bb and NTTS 045251+3016 and preliminary solutions for DF Tau, T Tau Sa-Sb, and ZZ Tau. Seven additional systems show curvature in their relative motion; currently we can place lower limits on their orbital periods. Full solutions will be possible as we obtain more coverage of their orbits. Five systems show motion that is indistinguishable from linear motion. Continued observations will confirm whether these systems are bound.
  69. Crossfield, I., Barman, T., Hansen, B., et al., 2013, prpl, Warm Ice Giant GJ 3470b: A Metal-rich, Hazy, or Low-Methane Atmosphere
    We report our spectroscopic investigation of the transiting ice giant GJ 3470b's atmospheric transmission, and the first results of extrasolar planet observations from the new Keck/MOSFIRE spectrograph. We measure a planet/star radius ratio of Rp/Rs = 0.0789 +/- 0.0020 in a bandpass from 2.09-2.36 micron and in six narrower bands across this wavelength range. When combined with existing broadband photometry, these measurements rule out cloud-free atmospheres in chemical equilibrium assuming either solar abundances (5.4 sigma confidence) or a moderate level of metal enrichment (50x solar abundances, 3.8 sigma), confirming previous results that such models are not representative for cool, low-mass, externally irradiated extrasolar planets. Current measurements are consistent with a flat transmission spectrum, which suggests that the atmosphere is explained by high-altitude clouds and haze, disequilibrium chemistry, unexpected abundance patterns, or the atmosphere is extremely metal-rich (>200x solar). Because GJ 3470b's low bulk density sets an upper limit on the planet's atmospheric enrichment of <300x solar, the atmospheric mean molecular weight must be <9. Thus, if the atmosphere is cloud-free its spectral features should be detectable with future observations. Transit observations at shorter wavelengths will provide the best opportunity to discriminate between plausible scenarios. We obtained optical spectroscopy with the GMOS spectrograph, but these observations exhibit large systematic uncertainties owing to thin, persistent cirrus conditions. Finally, we also provide the first detailed look at the steps necessary for well-calibrated MOSFIRE observations, and provide advice for future observations with this instrument.
  70. von Braun, K., Boyajian, T., van Belle, G., et al., 2013, prpl, Fundamental Parameters and Habitable Zones of Exoplanet Host Stars
    The assessment of whether liquid water can exist on the surface of an extrasolar planet, or indeed whether suitable conditions for habitability may exist, is primarily dependent on stellar astrophysical parameters. The star is the primary energy source of the system and influences every stage of planetary formation and evolution. Our interferometric survey of nearby exoplanet host stars with the CHARA Array produces angular radii of these stars. Coupled with literature photometry, SED fitting, and trigonometric parallaxes, we can furthermore directly determine stellar surface temperature and thus luminosity. We show recent results from our survey and discuss what they imply with respect to habitable zones of extrasolar planetary systems.
  71. Massey, P., 2013, NewAR, 57, 14, Massive stars in the galaxies of the Local Group
    The star-forming galaxies of the Local Group act as our laboratories for testing massive star evolutionary models. In this review, I briefly summarize what we believe we know about massive star evolution, and the connection between OB stars, Luminous Blue Variables, yellow supergiants, red supergiants, and Wolf-Rayet stars. The difficulties and recent successes in identifying these various types of massive stars in the neighboring galaxies of the Local Group will be discussed.
  72. van Belle, G., 2013, giec, 45, 40002, Directly Determined Linear Radii and Effective Temperatures of Giants from Long-Baseline Optical Interferometry
    A review of fundamental stellar parameters for giants as directly determined using long-baseline optical interferometry (LBI) will be presented. Special attention will be paid to the progression of precision over the years of the observables of linear radius and effective temperature, with the current state-of-the-art measures approaching sub-percent levels for hundreds of stars (and being limited primarily by the ancillary data products of distance and bolometric flux, not measured angular size). Discussion will also be presented on the diminishing meaning of these gross parameterizations of stellar atmospheres, as higher-order surface details such as limb darkening and spotting are beginning to be imaged with LBI.
  73. Baines, E., McAlister, H., ten Brummelaar, T., et al., (including van Belle, G.), 2013, ApJ, 772, 16, Characterization of the Red Giant HR 2582 Using the CHARA Array
    We present the fundamental parameters of HR 2582, a high-mass red giant star whose evolutionary state is a mystery. We used the CHARA Array interferometer to directly measure the star's limb-darkened angular diameter (1.006 0.020 mas) and combined our measurement with parallax and photometry from the literature to calculate its physical radius (35.76 5.31 R ), luminosity (517.8 17.5 L ), bolometric flux (14.8 0.5 10-8 erg s-1 cm-2), and effective temperature (4577 60 K). We then determined the star's mass (5.6 1.7 M ) using our new values with stellar oscillation results from Baudin et al. Finally, using the Yonsei-Yale evolutionary models, we estimated HR 2582's age to be 165^{+20}_{-15} Myr. While our measurements do not provide the precision required to definitively state where the star is in its evolution, it remains an excellent test case for evaluating stellar interior models.
  74. Baines, E., Armstrong, J., van Belle, G., 2013, ApJL, 771, L17, Navy Precision Optical Interferometer Observations of the Exoplanet Host Coronae Borealis and Their Implications for the Star's and Planet's Masses and Ages
    We used the Navy Precision Optical Interferometer to measure the limb-darkened angular diameter of the exoplanet host star CrB and obtained a value of 1.543 0.009 mas. We calculated its physical radius (5.06 0.04 R ) and used photometric measurements from the literature with our diameter to determine CrB's effective temperature (4788 17 K) and luminosity (12.13 0.09 L ). We then placed the star on an Hertzsprung-Russell diagram to ascertain the star's age (3.42^+0.32_-0.25 Gyr) and mass (1.47 0.04 M ) using a metallicity of [Fe/H] = +0.15. With this mass, we calculated the system's mass function with the orbital elements from a variety of sources, which produced a range of planetary masses: m psin i = 1.61-1.88 M Jup. We also updated the extent of the habitable zone for the system using our new temperature.
  75. Jorgensen, A., Schmitt, H., Mozurkewich, D., et al., (including van Belle, G.), 2013, AAS, 222, 304.05, Prospects for Unprecedented Imaging of Stellar Surfaces with the NPOI
    We present the design of a low-cost approach to making high-resolution images with the Navy Precision Optical Interferometer (NPOI) with resolution and fidelity better than any stellar images published to date. The capability combines several existing advances and infrastructure 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 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, and 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 hardware installed, and software enhancements can make this a reality. In this presentation we will give an overview of this potential new capability at NPOI and what it takes to get there.
  76. Massey, P., Neugent, K., Drout, M., et al., 2013, msao, 123, Yellow and Red Supergiants in the Local Group
    Yellow and red supergiants are the "poor cousins" of massive star studies, often overlooked in favor of strong emission-lined Wolf-Rayets or the spectacular, enigmatic Luminous Blue Variables. Recent studies, however, are proving the truth of Kippenhahn & Weigert (1990)'s claim that these evolved stages act as a "sort of magnifying glass, revealing relentlessly the faults of calculations of earlier phases." Identifying complete samples of YSGs and RSGs among the galaxies of the Local Group is difficult, as foreground dwarfs are nearly indistinguishable from bona-fide extragalactic members. We have succeeded in this task only by using a combination of wide-area photometry surveys combined with spectroscopic followup. Since massive star evolution is greatly affected by mass-loss, and mass-loss rates depend upon metallicity, we have conducted such studies over a range of 10 in metallicity, including the SMC, LMC, M33, and M31. These studies not only allow us to test the stellar evolutionary models, but the identification of these stars provides interesting kinematic information on the youngest stellar populations in these galaxies. We will review here what we have learned over the past few years, and what new questions these studies are raising.
  77. Neugent, K., Massey, P., Meynet, G., et al., 2013, msao, 128, The Wolf-Rayet Content of Local Group Galaxies
    The physics behind hot, massive stars is complicated, making the stars' evolution difficult to model. For this reason, we rely on observational tests to see how well stellar evolutionary theory predicts the relative numbers of various types of massive stars. The star-forming galaxies of the Local Group, with their varying metallicities, provide an excellent laboratory for such studies, as massive star evolution is strongly influenced by mass-loss rates, which in turn depend upon metallicity, at least on the main sequence. We've recently begun a far deeper, and more complete survey of the Wolf-Rayet (WR) content of Local Group galaxies compared to what has been done in the past. Using narrow-band interference filter imaging and following up with spectroscopy has allowed us to determine the number of WR stars in both M31 and M33 to ~ 5%. Given our previous knowledge of the WR content of the SMC and LMC, we can now examine how the relative number of WC-type and WN-type WRs varies with metallicity over a range of 10. Here we will present our current results as well as the follow-up work we are doing investigating the relative binary frequency of WRs in M31 and M33 to see if the unexpectedly large fraction of WCs in M31 are a product of binary evolution
  78. Sokal, K., Johnson, K., Indebetouw, R., et al., (including Massey, P.), 2013, msao, 184, An Emerging Wolf-Rayet Superstar Cluster in NGC 4449
    The formation of clusters of massive stars can dominate the energetics of a galaxy and cause catastrophic results to the host environment. Massive stars can have an important impact via winds even before they explode as SN, however the extent of their feedback effects has not been well-explored in the regime of Super Star Clusters (SSCs), which contain hundreds to thousands of massive stars in a single compact cluster. Young massive star clusters are obscured in their early stages by optically thick natal material, but are detectable early in their evolution as thermal free-free radio sources. Similar to galactic ultra-compact HII regions (which are less massive), these star forming regions are called ultra-dense HII regions (UDHIIs) and observed to have a flat or inverted radio spectral index. While embedded in natal material, stars will continue to evolve hidden inside and eventually supernova. Unexpectedly, however, we have identified a partially embedded massive cluster in NGC 4449 that is also harboring optical Wolf-Rayet (WR) stars (and thus is undergoing gas removal prior to supernova explosions). First detected as a radio continuum source with a thermal component, the cluster Source 26 (Reines et al. 2008) exhibits optical emission lines that reveal a large massive star population and confirm the presence of WR stars. We hypothesize that the most massive stars in the cluster have evolved into WRs and are blowing away the natal material with powerful winds to reveal the cluster, resulting in a vital yet short-lived phase in massive cluster evolution. If massive star winds drive the gas evolution of SSCs, this would contrast with less massive clusters in which supernova feedback dominates. Our discovery has initiated a small-scale survey to obtain optical spectra of known radio continuum sources indicative of thermal emission, and thus similar to the cluster in NGC 4449. We present an in-depth look at Source 26 in NGC 4449 from the optical massive star populations, including comparisons to evolutionary synthesis models, to the partially embedding material as evidenced by the IR, as well as a peek at first results from the survey.
  79. Hummel, C., Rivinius, T., Nieva, M., et al., (including van Belle, G.), 2013, A&A, 554, A52, Dynamical mass of the O-type supergiant in Orionis A

    Aims: A close companion of Orionis A was found in 2000 with the Navy Precision Optical Interferometer (NPOI), and shown to be a physical companion. Because the primary is a supergiant of type O, for which dynamical mass measurements are very rare, the companion was observed with NPOI over the full 7-year orbit. Our aim was to determine the dynamical mass of a supergiant that, due to the physical separation of more than 10 AU between the components, cannot have undergone mass exchange with the companion.
    Methods: The interferometric observations allow measuring the relative positions of the binary components and their relative brightness. The data collected over the full orbital period allows all seven orbital elements to be determined. In addition to the interferometric observations, we analyzed archival spectra obtained at the Calar Alto, Haute Provence, Cerro Armazones, and La Silla observatories, as well as new spectra obtained at the VLT on Cerro Paranal. In the high-resolution spectra we identified a few lines that can be associated exclusively to one or the other component for the measurement of the radial velocities of both. The combination of astrometry and spectroscopy then yields the stellar masses and the distance to the binary star.
    Results: The resulting masses for components Aa of 14.0 2.2 M and Ab of 7.4 1.1 M are low compared to theoretical expectations, with a distance of 294 21 pc which is smaller than a photometric distance estimate of 387 54 pc based on the spectral type B0III of the B component. If the latter (because it is also consistent with the distance to the Orion OB1 association) is adopted, the mass of the secondary component Ab of 14 3 M would agree with classifying a star of type B0.5IV. It is fainter than the primary by about 2.2 0.1 magnitudes in the visual. The primary mass is then determined to be 33 10 M. The possible reasons for the distance discrepancy are most likely related to physical effects, such as small systematic errors in the radial velocities due to stellar winds.

    Based in part on observations collected at the European Southern Observatory, Chile (Prop. No. 076.C-0431, 080.A-9021, 083.D-0589, 285.D-5042).

  80. Covino, E., Esposito, M., Barbieri, M., et al., (including Shkolnik, E.), 2013, A&A, 554, A28, The GAPS programme with HARPS-N at TNG. I. Observations of the Rossiter-McLaughlin effect and characterisation of the transiting system Qatar-1
    Context. Our understanding of the formation and evolution of planetary systems is still fragmentary because most of the current data provide limited information about the orbital structure and dynamics of these systems. The knowledge of the orbital properties for a variety of systems and at different ages yields information on planet migration and on star-planet tidal interaction mechanisms.
    Aims: In this context, a long-term, multi-purpose, observational programme has started with HARPS-N at TNG and aims to characterise the global architectural properties of exoplanetary systems. The goal of this first paper is to fully characterise the orbital properties of the transiting system Qatar-1 as well as the physical properties of the star and the planet.
    Methods: We exploit HARPS-N high-precision radial velocity measurements obtained during a transit to measure the Rossiter-McLaughlin effect in the Qatar-1 system, and out-of-transit measurements to redetermine the spectroscopic orbit. New photometric-transit light-curves were analysed and a spectroscopic characterisation of the host star atmospheric parameters was performed based on various methods (line equivalent width ratios, spectral synthesis, spectral energy distribution).
    Results: We achieved a significant improvement in the accuracy of the orbital parameters and derived the spin-orbit alignment of the system; this information, combined with the spectroscopic determination of the host star properties (rotation, Teff, log g, metallicity), allows us to derive the fundamental physical parameters for star and planet (masses and radii). The orbital solution for the Qatar-1 system is consistent with a circular orbit and the system presents a sky-projected obliquity of = - 8.4 7.1 deg. The planet, with a mass of 1.33 0.05 MJ, is found to be significantly more massive than previously reported. The host star is confirmed to be metal-rich ([Fe/H] = 0.20 0.10) and slowly rotating (vsinI = 1.7 0.3 km s-1), though moderately active, as indicated by the strong chromospheric emission in the Ca ii H&K line cores (log R'HK -4.60).
    Conclusions: We find that the system is well aligned and fits well within the general versus Teff trend. We can definitely rule out any significant orbital eccentricity. The evolutionary status of the system is inferred based on gyrochronology, and the present orbital configuration and timescale for orbital decay are discussed in terms of star-planet tidal interactions.

    Based on observations collected at the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Fundacion Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, in the frame of the programme Global Architecture of Planetary Systems (GAPS).Also based on observations collected at Asiago Observatory, and Calar Alto Observatory.Full Table 3 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/554/A28

  81. Desidera, S., Sozzetti, A., Bonomo, A., et al., (including Shkolnik, E.), 2013, A&A, 554, A29, The GAPS programme with HARPS-N at TNG. II. No giant planets around the metal-poor star HIP 11952
    In the context of the programme Global Architecture of Planetary Systems (GAPS), we have performed radial velocity monitoring of the metal-poor star HIP 11952 on 35 nights during about 150 days using the newly installed high-resolution spectrograph HARPS-N at the TNG and HARPS at the ESO 3.6 m telescope. The radial velocities show a scatter of 7 m s-1, compatible with the measurement errors for such a moderately warm metal-poor star (Teff = 6040 120 K; [Fe/H] = -1.9 0.1). We exclude the presence of the two giant planets with periods of 6.95 0.01 d and 290.0 16.2 d and radial velocity semi-amplitudes of 100.3 19.4 m s-1 and 105.2 14.7 m s-1, respectively, which have recently been announced. This result is important because HIP 11952 was thought to be the most metal-poor star hosting a planetary systemwith giant planets, which challenged some models of planet formation.

    Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundacion Galileo Galilei of the INAF at the Spanish Observatorio del Roque de los Muchachos of the IAC in the frame of the programme Global Architecture of Planetary Systems (GAPS). Based on observations collected at the La Silla Observatory, ESO (Chile): Program 185.D-0056.Table 1 is available in electronic form at http://www.aanda.org

  82. Ruiz-Rodriguez, D., Prato, L., Torres, G., et al., (including Wasserman, L.), 2013, AJ, 145, 162, RX J0513.1+0851 and RX J0539.9+0956: Two Young, Rapidly Rotating Spectroscopic Binary Stars
    RX J0513.1+0851 and RX J0539.9+0956 were previously identified as young, low-mass, single-lined spectroscopic binary systems and classified as weak-lined T Tauri stars at visible wavelengths. Here we present radial velocities, spectral types, vsin i values, and flux ratios for the components in these systems resulting from two-dimensional cross-correlation analysis. These results are based on high-resolution, near-infrared spectroscopy taken with the Keck II telescope to provide a first characterization of these systems as double-lined rather than single-lined. It applies the power of infrared spectroscopy to the detection of cool secondaries; the flux scales as a less steep function of mass in the infrared than in the visible, thus enabling an identification of low-mass secondaries. We found that the RX J0513.1+0851 and RX J0539.9+0956 primary stars are fast rotators, 60 km s-1 and 80 km s-1, respectively; this introduces extra difficulty in the detection of the secondary component as a result of the quite broad absorption lines. To date, these are the highest rotational velocities measured for a pre-main sequence spectroscopic binary. The orbital parameters and mass ratios were determined by combining new visible light spectroscopy with our infrared data for both systems. For RX J0513.1+0851, we derived a period of ~4 days and a mass ratio of q = 0.46 0.01 and for RX J0539.9+0956, a period of ~1117 days and a mass ratio of q = 0.66 0.01. Based on our derived properties for the stellar components, we estimate the luminosities and hence distances to these binaries at 220 pc and 90 pc. They appear to be significantly closer than previously estimated.
  83. Richardson, N., Schaefer, G., Gies, D., et al., (including Matson, R., Aldoretta, E.), 2013, ApJ, 769, 118, The H-band Emitting Region of the Luminous Blue Variable P Cygni: Spectrophotometry and Interferometry of the Wind
    We present the first high angular resolution observations in the near-infrared H band (1.6 m) of the luminous blue variable star P Cygni. We obtained six-telescope interferometric observations with the CHARA Array and the MIRC beam combiner. These show that the spatial flux distribution is larger than expected for the stellar photosphere. A two-component model for the star (uniform disk) plus a halo (two-dimensional Gaussian) yields an excellent fit of the observations, and we suggest that the halo corresponds to flux emitted from the base of the stellar wind. This wind component contributes about 45% of the H-band flux and has an angular FWHM = 0.96 mas, compared to the predicted stellar diameter of 0.41 mas. We show several images reconstructed from the interferometric visibilities and closure phases, and they indicate a generally spherical geometry for the wind. We also obtained near-infrared spectrophotometry of P Cygni from which we derive the flux excess compared to a purely photospheric spectral energy distribution. The H-band flux excess matches that from the wind flux fraction derived from the two-component fits to the interferometry. We find evidence of significant near-infrared flux variability over the period from 2006 to 2010 that appears similar to the variations in the H emission flux from the wind.
  84. Johnson, M., 2013, AJ, 145, 146, Determining the Nature of the Extended H I Structure around LITTLE THINGS Dwarf Galaxy NGC 1569
    This work presents an extended, neutral hydrogen emission map around Magellanic-type dwarf irregular galaxy (dIm) NGC 1569. In the spring of 2010, the Robert C. Byrd Green Bank Telescope was used to map a 9 2 region in H I line emission that includes NGC 1569 and IC 342 as well as two other dwarf galaxies. The primary objective for these observations was to search for structures potentially connecting NGC 1569 with IC 342 group members in order to trace previous interactions and thus, provide an explanation for the starburst and peculiar kinematics prevalent in NGC 1569. A large, half-degree diameter H I cloud was detected that shares the same position and velocity as NGC 1569. Also, two long structures were discovered that are reminiscent of intergalactic filaments extending out in a V-shaped manner from NGC 1569 toward UGCA 92, a nearby dwarf galaxy. These filamentary structures extend for about 1.5, which is 77 kpc at NGC 1569. There is a continuous velocity succession with the 0.5 H I cloud, filaments, and main body of the galaxy. The 0.5 H I cloud and filamentary structures may be foreground Milky Way, but are suggestive as possible remnants of an interaction between NGC 1569 and UGCA 92. The data also show two tidal tails extending from UGCA 86 and IC 342, respectively. These structures may be part of a continuous H I bridge but more data are needed to determine if this is the case.
  85. Jacoby, G., Ciardullo, R., De Marco, O., et al., (including Herrmann, K.), 2013, ApJ, 769, 10, A Survey for Planetary Nebulae in M31 Globular Clusters
    We report the results of an [O III] 5007 spectroscopic survey for planetary nebulae (PNe) located within the star clusters of M31. By examining R ~ 5000 spectra taken with the WIYN+Hydra spectrograph, we identify 3 PN candidates in a sample of 274 likely globular clusters, 2 candidates in objects which may be globular clusters, and 5 candidates in a set of 85 younger systems. The possible PNe are all faint, between ~2.5 and ~6.8 mag down the PN luminosity function, and, partly as a consequence of our selection criteria, have high excitation, with [O III] 5007 to H ratios ranging from 2 to >~ 12. We discuss the individual candidates, their likelihood of cluster membership, and the possibility that they were formed via binary interactions within the clusters. Our data are consistent with the suggestion that PN formation within globular clusters correlates with binary encounter frequency, though, due to the small numbers and large uncertainties in the candidate list, this study does not provide sufficient evidence to confirm the hypothesis.
  86. Husser, T., Wende-von Berg, S., Dreizler, S., et al., (including Barman, T.), 2013, A&A, 553, A6, A new extensive library of PHOENIX stellar atmospheres and synthetic spectra

    Aims: We present a new library of high-resolution synthetic spectra based on the stellar atmosphere code PHOENIX that can be used for a wide range of applications of spectral analysis and stellar parameter synthesis.
    Methods: The spherical mode of PHOENIX was used to create model atmospheres and to derive detailed synthetic stellar spectra from them. We present a new self-consistent way of describing micro-turbulence for our model atmospheres.
    Results: The synthetic spectra cover the wavelength range from 500 A to 5.5 m with resolutions of R = 500 000 in the optical and near IR, R = 100 000 in the IR and = 0.1 A in the UV. The parameter space covers 2300 K Teff 12 000 K, 0.0 log g +6.0, - 4.0 [Fe/H] +1.0, and - 0.2 [/Fe] +1.2. The library is a work in progress and we expect to extend it up to Teff = 25 000 K.
  87. Grzenia, B., Tycner, C., Jones, C., et al., (including van Belle, G.), 2013, AJ, 145, 141, Modeling Circumstellar Disks of B-type Stars with Observations from the Palomar Testbed Interferometer
    Geometrical (uniform disk) and numerical models were calculated for a set of B-emission (Be) stars observed with the Palomar Testbed Interferometer (PTI). Physical extents have been estimated for the disks of a total of 15 stars via uniform disk models. Our numerical non-LTE models used parameters for the B0, B2, B5, and B8 spectral classes and following the framework laid by previous studies, we have compared them to infrared K-band interferometric observations taken at PTI. This is the first time such an extensive set of Be stars observed with long-baseline interferometry has been analyzed with self-consistent non-LTE numerical disk models.
  88. Massey, P., Neugent, K., Hillier, D., et al., 2013, ApJ, 768, 6, A Bake-off between CMFGEN and FASTWIND: Modeling the Physical Properties of SMC and LMC O-type Stars
    The model atmosphere programs FASTWIND and CMFGEN are both elegantly designed to perform non-LTE analyses of the spectra of hot massive stars, and include sphericity and mass-loss. The two codes differ primarily in their approach toward line blanketing, with CMFGEN treating all of the lines in the co-moving frame and FASTWIND taking an approximate approach which speeds up execution times considerably. Although both have been extensively used to model the spectra of O-type stars, no studies have used the codes to independently model the same spectra of the same stars and compare the derived physical properties. We perform this task on 10 O-type stars in the Magellanic Clouds. For the late-type O supergiants, both CMFGEN and FASTWIND have trouble fitting some of the He I lines, and we discuss causes and cures. We find that there is no difference in the average effective temperatures found by the two codes for the stars in our sample, although the dispersion is large, due primarily to the various difficulties each code has with He I. The surface gravities determined using FASTWIND are systematically lower by 0.12 dex compared to CMFGEN, a result we attribute to the better treatment of electron scattering by CMFGEN. This has implications for the interpretation of the origin of the so-called mass discrepancy, as the masses derived by FASTWIND are on average lower than inferred from stellar evolutionary models, while those found by CMFGEN are in better agreement.
  89. Grundy, W., Olkin, C., Young, L., et al., 2013, Icar, 223, 710, Near-infrared spectral monitoring of Pluto's ices: Spatial distribution and secular evolution
    We report results from monitoring Pluto's 0.8 to 2.4 m reflectance spectrum with IRTF/SpeX on 65 nights over the dozen years from 2001 to 2012. The spectra show vibrational absorption features of simple molecules CH4, CO, and N2 condensed as ices on Pluto's surface. These absorptions are modulated by the planet's 6.39 day rotation period, enabling us to constrain the longitudinal distributions of the three ices. Absorptions of CO and N2 are concentrated on Pluto's anti-Charon hemisphere, unlike absorptions of less volatile CH4 ice that are offset by roughly 90 from the longitude of maximum CO and N2 absorption. In addition to the diurnal variations, the spectra show longer term trends. On decadal timescales, Pluto's stronger CH4 absorption bands have been getting deeper, while the amplitude of their diurnal variation is diminishing, consistent with additional CH4 absorption at high northern latitudes rotating into view as the sub-Earth latitude moves north (as defined by the system's angular momentum vector). Unlike the CH4 absorptions, Pluto's CO and N2 absorptions appear to be declining over time, suggesting more equatorial or southerly distributions of those species. Comparisons of geometrically-matched pairs of observations favor geometric explanations for the observed secular changes in CO and N2 absorption, although seasonal volatile transport could be at least partly responsible. The case for a volatile transport contribution to the secular evolution looks strongest for CH4 ice, despite it being the least volatile of the three ices.
  90. Crossfield, I., Barman, T., Hansen, B., et al., 2013, EPJWC, 47, 13005, Re-evaluating hot Jupiter WASP-12b: An update
    The hot Jupiter WASP-12b is one of the largest, hottest, and best-studied extrasolar planets. We revisit our recent analysis of WASP-12b's emission spectrum in light of near-infrared spectroscopic measurements which have been claimed to support either a hydride-dominated or carbon-rich atmospheric composition. We show that this new spectrum is still consistent with a featureless blackbody, indicating a nearly isothermal photosphere on the planet's day side. Thus the ensemble of occultation measurements for WASP-12b is still insufficient to constrain the planet's atmospheric composition.
  91. Scandariato, G., Maggio, A., Lanza, A., et al., (including Shkolnik, E.), 2013, A&A, 552, A7, A coordinated optical and X-ray spectroscopic campaign on HD 179949: searching for planet-induced chromospheric and coronal activity
    Context. HD 179949 is an F8V star, orbited by a close-in giant planet with a period of ~3 days. Previous studies suggested that the planet enhances the magnetic activity of the parent star, producing a chromospheric hot spot which rotates in phase with the planet orbit. However, this phenomenon is intermittent since it was observed in several but not all seasons.
    Aims: A long-term monitoring of the magnetic activity of HD 179949 is required to study the amplitude and time scales of star-planet interactions.
    Methods: In 2009 we performed a simultaneous optical and X-ray spectroscopic campaign to monitor the magnetic activity of HD 179949 during ~5 orbital periods and ~2 stellar rotations. We analyzed the Ca ii H&K lines as a proxy for chromospheric activity, and we studied the X-ray emission in search of flux modulations and to determine basic properties of the coronal plasma.
    Results: A detailed analysis of the flux in the cores of the Ca ii H&K lines and a similar study of the X-ray photometry shows evidence of source variability, including one flare. The analysis of the time series of chromospheric data indicates a modulation with a ~11 days period, compatible with the stellar rotation period at high latitudes. Instead, the X-ray light curve suggests a signal with a period of ~4 days, consistent with the presence of two active regions on opposite hemispheres.
    Conclusions: The observed variability can be explained, most likely, as due to rotational modulation and to intrinsic evolution of chromospheric and coronal activity. There is no clear signature related to the orbital motion of the planet, but the possibility that just a fraction of the chromospheric and coronal variability is modulated with the orbital period of the planet, or the stellar-planet beat period, cannot be excluded. We conclude that any effect due to the presence of the planet is difficult to disentangle.
  92. Parker, A., Buie, M., Osip, D., et al., (including Wasserman, L.), 2013, AJ, 145, 96, 2011 HM102: Discovery of a High-inclination L5 Neptune Trojan in the Search for a Post-Pluto New Horizons Target
    We present the discovery of a long-term stable L5 (trailing) Neptune Trojan in data acquired to search for candidate trans-Neptunian objects for the New Horizons spacecraft to fly by during an extended post-Pluto mission. This Neptune Trojan, 2011 HM102, has the highest inclination (29.4) of any known member of this population. It is intrinsically brighter than any single L5 Jupiter Trojan at HV ~ 8.18. We have determined its gri colors (a first for any L5 Neptune Trojan), which we find to be similar to the moderately red colors of the L4 Neptune Trojans, suggesting similar surface properties for members of both Trojan clouds. We also present colors derived from archival data for two L4 Neptune Trojans (2006 RJ103 and 2007 VL305), better refining the overall color distribution of the population. In this document we describe the discovery circumstances, our physical characterization of 2011 HM102, and this object's implications for the Neptune Trojan population overall. Finally, we discuss the prospects for detecting 2011 HM102 from the New Horizons spacecraft during its close approach in mid- to late-2013.
  93. Johnson, J., Shepard, M., Grundy, W., et al., 2013, Icar, 223, 383, Spectrogoniometry and modeling of martian and lunar analog samples and Apollo soils
    We present new visible/near-infrared multispectral reflectance measurements of seven lunar soil simulants, two Apollo soils, and eight martian analog samples as functions of illumination and emission angles using the Bloomsburg University Goniometer. By modeling these data with Hapke theory, we provide constraints on photometric parameters (single scattering albedo, phase function parameters, macroscopic roughness, and opposition effect parameters) to provide additional ground truth photometric properties to assist analyses of spacecraft data. A wide range of modeled photometric properties were variably related to albedo, color, grain size, and surface texture. Finer-grained samples here have high single-scattering albedo values compared to their coarser-grained counterparts, as well as lower macroscopic roughness values. The Mars analog samples and Apollo soils exhibit slightly lower opposition effect width parameter values than the lunar analogs, whereas the opposition effect magnitude is not well constrained by the models. The Mars analog soils are typically relatively backscattering and consistent with fairly rough particles with a moderate density of internal scatterers, similar to the in situ observations of some soils by the Mars Exploration Rover (MER) Spirit. Some lunar analog soil models result in moderately-forward scattering behaviors, as do the two Apollo soils. Other fine-grained and/or glass-rich lunar analog samples populate a narrowly forward-scattering regime similar to model results from observations of some rover tracks observed by the MER Opportunity rover and some dust-poor gray rocks by the Spirit rover. An experiment to mimic the spherule-rich soils observed by Opportunity demonstrated a large decrease in single-scattering albedo compared to spherule-free soil surfaces, as well as increased surface roughness, narrow opposition effects, and a significant increase in backscattering, similar to some of the Opportunity soils. Phase reddening effects are documented in many soils as an increase in near-infrared/visible ratios with phase angle. Some samples exhibit falloffs in these ratio phase curves at phase angles beyond 50-80 that are likely related to an increased importance of surface scattering at high phase angles. None of the lunar analog soils perfectly match the modeled photometric parameters of the two Apollo soils. The phase reddening nature of the mare soil included an upturn in ratio values at phase angles <10 that was not observed for the highland sample. It remains to be verified whether this is a consistent observation between mare and highland samples.
  94. Elmegreen, B., Rubio, M., Hunter, D., et al., 2013, Natur, 495, 487, Carbon monoxide in clouds at low metallicity in the dwarf irregular galaxy WLM
    Carbon monoxide (CO) is the primary tracer for interstellar clouds where stars form, but it has never been detected in galaxies in which the oxygen abundance relative to hydrogen is less than 20 per cent of that of the Sun, even though such `low-metallicity' galaxies often form stars. This raises the question of whether stars can form in dense gas without molecules, cooling to the required near-zero temperatures by atomic transitions and dust radiation rather than by molecular line emission; and it highlights uncertainties about star formation in the early Universe, when the metallicity was generally low. Here we report the detection of CO in two regions of a local dwarf irregular galaxy, WLM, where the metallicity is 13 per cent of the solar value. We use new submillimetre observations and archival far-infrared observations to estimate the cloud masses, which are both slightly greater than 100,000 solar masses. The clouds have produced stars at a rate per molecule equal to 10 per cent of that in the local Orion nebula cloud. The CO fraction of the molecular gas is also low, about 3 per cent of the Milky Way value. These results suggest that in small galaxies both star-forming cores and CO molecules become increasingly rare in molecular hydrogen clouds as the metallicity decreases.
  95. Konopacky, Q., Barman, T., Macintosh, B., et al., 2013, Sci, 339, 1398, Detection of Carbon Monoxide and Water Absorption Lines in an Exoplanet Atmosphere
    Determining the atmospheric structure and chemical composition of an exoplanet remains a formidable goal. Fortunately, advancements in the study of exoplanets and their atmospheres have come in the form of direct imagingspatially resolving the planet from its parent starwhich enables high-resolution spectroscopy of self-luminous planets in jovian-like orbits. Here, we present a spectrum with numerous, well-resolved molecular lines from both water and carbon monoxide from a massive planet orbiting less than 40 astronomical units from the star HR 8799. These data reveal the planets chemical composition, atmospheric structure, and surface gravity, confirming that it is indeed a young planet. The spectral lines suggest an atmospheric carbon-to-oxygen ratio that is greater than that of the host star, providing hints about the planets formation.
  96. Shkolnik, E., 2013, ApJ, 766, 9, An Ultraviolet Investigation of Activity on Exoplanet Host Stars
    Using the far-UV (FUV) and near-UV (NUV) photometry from the NASA Galaxy Evolution Explorer (GALEX), we searched for evidence of increased stellar activity due to tidal and/or magnetic star-planet interactions (SPI) in the 272 known FGK planetary hosts observed by GALEX. With the increased sensitivity of GALEX, we are able probe systems with lower activity levels and at larger distances than what has been done to date with X-ray satellites. We compared samples of stars with close-in planets (a < 0.1 AU) to those with far-out planets (a > 0.5 AU) and looked for correlations of excess activity with other system parameters. This statistical investigation found no clear correlations with a, Mp , or Mp /a, in contrast to some X-ray and Ca II studies. However, there is tentative evidence (at a level of 1.8) that stars with radial-velocity-(RV)-detected close-in planets are more FUV-active than stars with far-out planets, in agreement with several published X-ray and Ca II results. The case is strengthened to a level of significance to 2.3 when transit-detected close-in planets are included. This is most likely because the RV-selected sample of stars is significantly less active than the field population of comparable stars, while the transit-selected sample is similarly active. Given the factor of 2-3 scatter in fractional FUV luminosity for a given stellar effective temperature, it is necessary to conduct a time-resolved study of the planet hosts in order to better characterize their UV variability and generate a firmer statistical result.

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

  97. Sahlmann, J., Henning, T., Queloz, D., et al., (including van Belle, G.), 2013, A&A, 551, A52, The ESPRI project: astrometric exoplanet search with PRIMA. I. Instrument description and performance of first light observations
    Context. The ESPRI project relies on the astrometric capabilities offered by the PRIMA facility of the Very Large Telescope Interferometer for discovering and studying planetary systems. Our survey consists of obtaining high-precision astrometry for a large sample of stars over several years to detect their barycentric motions due to orbiting planets. We present the operation's principle, the instrument's implementation, and the results of a first series of test observations.
    Aims: We give a comprehensive overview of the instrument infrastructure and present the observation strategy for dual-field relative astrometry in the infrared K-band. We describe the differential delay lines, a key component of the PRIMA facility that was delivered by the ESPRI consortium, and discuss their performance within the facility. This paper serves as reference for future ESPRI publications and for the users of the PRIMA facility.
    Methods: Observations of bright visual binaries were used to test the observation procedures and to establish the instrument's astrometric precision and accuracy. The data reduction strategy for the astrometry and the necessary corrections to the raw data are presented. Adaptive optics observations with NACO were used as an independent verification of PRIMA astrometric observations.
    Results: The PRIMA facility was used to carry out tests of astrometric observations. The astrometric performance in terms of precision is limited by the atmospheric turbulence at a level close to the theoretical expectations and a precision of 30 as was achieved. In contrast, the astrometric accuracy is insufficient for the goals of the ESPRI project and is currently limited by systematic errors that originate in the part of the interferometer beamtrain that is not monitored by the internal metrology system.
    Conclusions: Our observations led to defining corrective actions required to make the facility ready for carrying out the ESPRI search for extrasolar planets.

    Part of this work is based on technical observations collected at the European Southern Observatory at Paranal, Chile. The raw data is publicly accessible at the ESO Science Archive Facility (http://archive.eso.org/).

  98. Hillenbrand, L., Miller, A., Covey, K., et al., 2013, AJ, 145, 59, Highly Variable Extinction and Accretion in the Jet-driving Class I-type Young Star PTF 10nvg (V2492 Cyg, IRAS 20496+4354)
    We report extensive new photometry and spectroscopy of the highly variable young stellar object PTF 10nvg (also known as IRAS 20496+4354 and V2492 Cyg), including optical and near-infrared time-series data as well as mid-infrared and millimeter data. Following the previously reported 2010 rise to R PTF lsim13.5 and subsequent fade, during 2011 and 2012 the source underwent additional episodes of brightening, followed by several magnitude dimming events including prolonged faint states at R PTF >~ 20m. The observed high-amplitude variations are largely consistent with extinction changes (AV up to 30 mag) having a ~220 day quasi-periodic signal. However, photometry measured when the source was near maximum brightness in mid-2010 as well as in late-2012 does not phase well to this period. Spectral evolution includes not only changes in the spectral slope but also correlated variation in the prominence of TiO/VO/CO bands and atomic line emission, as well as anti-correlated variation in forbidden line emission which, along with H2, dominates optical and infrared spectra at faint epochs. Notably, night-to-night variations in several forbidden doublet strengths and ratios are observed. High-dispersion spectra were obtained in a variety of photometric states and reveal time-variable line profiles. Neutral and singly ionized atomic species are likely formed in an accretion flow and/or impact while the origin of zero-velocity atomic Li I 6707 in emission is unknown. Forbidden lines, including several rare species, exhibit blueshifted emission profiles and likely arise from an outflow/jet. Several of these lines are also seen spatially offset from the continuum source position, presumably in a shocked region of an extended jet. Blueshifted absorption components of the Na I D doublet, K I 7665, 7669 doublet, and the O I 7774 triplet, as well as blueshifted absorption components seen against the broad H and Ca II triplet emission lines, similarly are formed in the outflow. CARMA maps resolve on larger scales a spatially extended outflow in millimeter-wavelength CO. We attribute the recently observed photometric and spectroscopic behavior to rotating circumstellar disk material located at separation a 0.7(M */M )1/3 AU from the continuum source, causing the semi-periodic dimming. Occultation of the central star as well as the bright inner disk and the accretion/outflow zones renders shocked gas in the inner part of the jet amenable to observation at the faint epochs. We discuss PTF 10nvg as a source exhibiting both accretion-driven (perhaps analogous to V1647 Ori) and extinction-driven (perhaps analogous to UX Ori or GM Cep) high-amplitude variability phenomena.
  99. Roe, H., Schaller, E., Brown, M., et al., 2013, noao, 56, Titan's Methane Weather post-Equinox: Seasonal climate change and large storm systems
    Titan's troposphere hosts a methane-based meteorology in direct analogy to Earth's water-based meteorology. Titan's atmosphere is a dynamic system with significant weather events regularly occurring on top of the backdrop of dramatic seasonal changes. The combination of Titan's long year (30 Earth years) with significant weather events occurring on timescales of a few days is a challenge to observing programs and spacecraft to acquire the data necessary to understand the complex seasonal cycles. We have assembled a network of ground-based telescopes to study Titan's weather, from small telescope photometry to spatially resolved imaging with ToO observations on Gemini. Observing Titan's clouds requires only a small amount (15-25 min) of large (8-10 meter) adaptive optics telescope time and queued Gemini observations are uniquely suited to this program. As Titan's northern spring progresses (equinox was in August 2009), continued observations are required to monitor the advance of the planetary scale monsoon and identify and characterize large storm systems as they emerge.
  100. Jensen, A., Redfield, S., Cochran, W., et al., (including Barman, T.), 2013, noao, 174, A Detailed Study of the Hot n=2 Hydrogen in Transiting Exoplanet HD 189733b
    We propose to use Keck/HIRESr for a comprehensive study of the excited n=2 hydrogen (through H(alpha) and H(beta) transmission spectroscopy) in transiting exoplanet HD 189733b, where the first detection of H(alpha) in an exoplanet's atmosphere was made by Jensen et al. (2012). Both spectrophotometric (``transit-like") and high- resolution transmission spectroscopic methods will be used to search for all n=2 hydrogen absorption lines-H(alpha), H(beta), H(gamma), etc. We predict the first-ever detection of H(beta) in an exoplanet and an independent confirmation of H(alpha) at great statistical significance (>4sigma and 10s of sigma, respectively), and upper limits or possible detections of higher-energy transitions (depending on the amount that the detected H(alpha) is saturated). We require two separate transits to achieve this sensitivity. These measurements will allow for direct measurements of column density and probe the full hydrogen envelope via temporal variations. We will search for timing variations in the transit contact points in order to directly detect the size of the n=2 hydrogen envelope. This is only possible with the combination of time resolution, full transit coverage, and high sensitivity provided by Keck. The high spectral resolution of HIRES will allow us to make a direct comparison with it HST observations of Ly(alpha) for HD189733b.
  101. Sokal, K., Johnson, K., Massey, P., et al., 2013, noao, 317, Emerging Wolf-Rayet Stars in Embedded Super Star Clusters
    The formation of massive stars, especially when clustered, can alter galaxy energetics. The presence of even a few Wolf-Rayet stars (WRs) can drastically impact a young massive star cluster's evolution and may be critical in removing natal gas. However, the impact on the star formation environment of the cluster is not well understood. Observing young massive clusters will provide insight into their formation timescales and evolution, possibly driven by WRs whose short lifespans provide tight age constraints. We target one of the earliest stages of massive star clusters, detectable via thermal free-free radio emission resulting from optically thick natal material enshrouding the cluster, termed Ultra-Dense HII regions (UDHIIs). We hypothesize that the most massive stars may evolve into WRs while the cluster is still embedded and be revealed as their strong winds blow away the natal material, resulting in an important and brief phase in cluster evolution. We propose to obtain optical spectra of embedded UDHIIs in various galaxies to identify WR populations. Contrasting the clusters will enable the identification of the stages of early cluster evolution, providing insight into the stages when Wolf-Rayet stars can be detected and their effects on the surrounding material.
  102. Covey, K., Prato, L., Torres, G., et al., 2013, noao, 405, A coordinated optical/NIR survey for low-mass pre-main sequence binaries in NGC 2264
    Pre-main sequence binaries are critical laboratories for validating theoretical models of star formation and early stellar evolution. Identifying young binaries, however, is challenging: changes in a young star's accretion rate, or in the projected area of photospheric star- spots, induce high levels of photometric and spectroscopic variability that can easily mask eclipses and/or radial velocity variations due to low-mass companions. We propose to use 1.5 nights of Hectochelle/MMT observations, in coordination with an approved ancillary science program with the SDSS-III APOGEE NIR spectrograph, to conduct a coordinated optical/NIR search for spectroscopic binaries in NGC 2264, a rich Galactic star forming region. Combining these contemporaneous optical and NIR spectra, we will identify several new bona-fide pre-main sequence spectroscopic binaries and provide preliminary characterizations of their orbits to inform subsequent follow-up observations with single-object spectrographs. Using additional fibers, we will acquire new epochs for 6 known spectroscopic binaries, characterize highly variable YSOs identified in joint CoroT/Spitzer monitoring of NGC 2264, and calibrate the relationship between a star's optical RV jitter and the level of accretion or chromospheric activity indicated by its H_(alpha) line strength.
  103. Verbiscer, A., Grundy, W., Benecchi, S., et al., 2013, noao, 435, Mutual Event of Transneptunian Binary (79360) Sila-Nunam
    The transneptunian binary (79360) Sila-Nunam (provisionally designated 1997 CS29) is currently undergoing mutual events in which the two nearly-equal brightness components alternate in eclipsing and occulting each other as seen from Earth (Grundy et al. 2012, Verbiscer et al. 2012a). The low eccentricity of the orbit, determined from Hubble Space Telescope observations of the resolved components (Grundy et al. 2012), and the coincidence of the system's photometric lightcurve and orbital period are consistent with a system that is tidally locked and synchronized, like that of Pluto-Charon. Mutual events provide a rich opportunity to learn about size, shape, color, and albedo patterns on the system components. Mutual events of Pluto-Charon observed between 1985-1990 provided the first characterization of their albedo distributions. The duration of the mutual event season depends on the size and separation of the system components. Using sizes determined from thermal observations, the mutual event season for Sila-Nunam should last about a decade; however, the deepest, most central (and thus most informative) events are predicted to be observable in the 2013 apparition, with progressively shallower events observable thereafter for the next 4-5 years. Gemini-North is ideally located to observe a complete mutual event of Sila-Nunam which begins at 5:59 UT on 14 February 2013 and ends at 14:17. Since Sila-Nunam will be near opposition, the target is visible to GMOS for the entire night. This event is a rare opportunity to determine the size, density, and albedo/color patterns on a primitive body which has likely been unaltered since the time of Solar System formation.
  104. von Braun, K., Boyajian, T., van Belle, G., 2013, EAS, 64, 429, Predicting Stellar Angular Sizes
    Our survey of long-baseline infrared and optical interferometry measurements is producing considerable numbers of directly determined stellar angular sizes. We use our sample of 124 high-precision (5%) angular stellar diameter values and correlate them with stellar magnitude values from the literature to produce empirical relations for main-sequence stars between observed apparent magnitudes, stellar colors, and angular sizes (surface brightness relations). We find a significant dependence on stellar metallicity for (B - V) colors. The scatter in the calculated relations is small (5%), which makes them a robust tool for the prediction of main-sequence stellar angular sizes based on photometry. We apply these relations via the calculation of the radius of the multiplanet host star GJ 667 C.
  105. Knight, M., Schleicher, D., 2013, Icar, 222, 691, The highly unusual outgassing of Comet 103P/Hartley 2 from narrowband photometry and imaging of the coma
    We report on photometry and imaging of Comet 103P/Hartley 2 obtained at Lowell Observatory from 1991 through 2011. We acquired photoelectric photometry on two nights in 1991, four nights in 1997/1998, and 13 nights in 2010/2011. We observed a strong secular decrease in water and all other observed species production in 2010/2011 from the 1991 and 1997/1998 levels. We see evidence for a strong asymmetry with respect to perihelion in the production rates of our usual bandpasses, with peak production occurring 10 days post-perihelion and production rates considerably higher post-perihelion. The composition was "typical," in agreement with the findings of other investigators. We obtained imaging on 39 nights from 2010 July until 2011 January. We find that, after accounting for their varying parentage and lifetimes, the C2 and C3 coma morphology resemble the CN morphology we reported previously. These species exhibited an hourglass shape in October and November, and the morphology changed with rotation and evolved over time. The OH and NH coma morphology showed hints of an hourglass shape near the nucleus, but was also enhanced in the anti-sunward hemisphere. This tailward brightness enhancement did not vary significantly with rotation and evolved with the viewing geometry. We conclude that all five gas species likely originate from the same source regions on the nucleus, but that OH and NH were derived from small grains of water and ammonia ice that survived long enough to be affected by radiation pressure and driven in the anti-sunward direction. We detected the faint, sunward facing dust jet reported by other authors, and did not detect a corresponding gas feature. This jet varied little during a night but exhibited some variations from night to night, suggesting it is located near the total angular momentum vector. Overall, our imaging results support the conclusions of other authors that Hartley 2's "hyperactivity" is caused by icy particles of various sizes that are lifted off the surface and break up in the coma to greatly increase the effective active surface area.
  106. Lisse, C., Christian, D., Wolk, S., et al., (including Knight, M.), 2013, Icar, 222, 752, Chandra ACIS-S imaging spectroscopy of anomalously faint X-ray emission from Comet 103P/Hartley 2 during the EPOXI encounter
    We present results from the Chandra X-ray Observatory's characterization of the X-ray emission from Comet 103P/Hartley 2, in support of NASA's Deep Impact Extended close flyby of the comet on 04 November 2010. The comet was observed 4 times for a total on target time of 60 ks between the 17th of October and 16th of November 2010, with two of the visits occurring during the EPOXI close approach on 04 November and 05 November 2010. X-ray emission from 103P was qualitatively similar to that observed for collisionally thin Comets 2P/Encke (Lisse, C.M. et al. [2005]. Astrophys. J. 635, 1329-1347) and 9P/Tempel 1 (Lisse, C.M. et al. [2007]. Icarus 190, 391-405). Emission morphology offset sunward but asymmetrical from the nucleus and emission lines produced by charge exchange between highly stripped C, N, and O solar wind minor ions and coma neutral gas species were found. The comet was very under-luminous in the X-ray at all times, representing the 3rd faintest comet ever detected (LX = 1.1 0.3 1014 erg s-1). The coma was collisionally thin to the solar wind at all times, allowing solar wind ions to flow into the inner coma and interact with the densest neutral coma gas. Localization of the X-ray emission in the regions of the major rotating gas jets was observed, consistent with the major source of cometary neutral gas species being icy coma dust particles. Variable spectral features due to changing solar wind flux densities and charge states were also seen. Modeling of the Chandra observations from the first three visits using observed gas production rates and ACE solar wind ion fluxes with a charge exchange mechanism for the emission is consistent with the temporal and spectral behavior expected for a slow, hot wind typical of low latitude emission from the solar corona interacting with the comet's neutral coma. The X-ray emission during the 4th visit on 16 November 2010 is similar to the unusual behavior seen for Comet 17P/Holmes in 2007 (Christian, D.J. et al. [2010]. Astrophys. J. Suppl. 187, 447-459) as the solar wind became dominated by a less ionized and faster plasma, more typical of outflow from polar coronal hole regions. We postulate that the overall faintness of the comet seen during all visits is due to the unusually well mixed dust and gas content of this hyperactive comet's coma producing Auger electrons rather than X-rays via charge exchange with the solar wind. An alternative possible explanation for the faintness of the comet's X-ray emission, and its unusual high CV and unusually low CVI emission, is that the impinging solar wind was drastically slowed in the inner coma, below 150 km s-1, before charge exchanging with cometary neutrals.
  107. Bochanski, J., Hawley, S., Covey, K., et al., 2013, AN, 334, 44, Measuring the ages of low-mass stars and brown dwarfs
    Age is among the most elusive, yet important, fundamental properties of low-mass stars and brown dwarfs. M dwarfs have main-sequence lifetimes that are estimated to be trillions of years, with little change in luminosity. In contrast, brown dwarfs cool and dim with time, resulting in a significant degeneracy between mass, age, and luminosity. Despite these inherent challenges, there have been recent efforts on both observational and theoretical fronts that may yield precise ages for low-mass stars and brown dwarfs. We feature some current observational efforts focused on estimating ages of these objects as presented in our Cool Stars 17 splinter session.
  108. Burgasser, A., Faherty, J., Schmidt, S., et al., (including Shkolnik, E.), 2013, AN, 334, 93, The kinematics of very low mass dwarfs: Splinter session summary
    Kinematic investigations are being increasingly deployed in studies of the lowest mass stars and brown dwarfs to investigate their origins, characterize their atmospheres, and examine the evolution of their physical parameters. This article summarizes the contributions made at the ``Kinematics of Very Low Mass Dwarfs'' splinter session. Results discussed include analysis of kinematic distributions of M, L, and T dwarfs; theoretical tools for interpreting these distributions; identifications of very low mass halo dwarfs and wide companions to nearby stars; radial velocity variability among young and very cool brown dwarfs; and the search and identification of M dwarfs in young moving groups. A summary of discussion points at the conclusion of the splinter sesseion is also presented.
  109. Meibom, S., Barnes, S., Covey, K., et al., 2013, AN, 334, 168, Angular momentum evolution of cool stars: Toward a synthesis of observations and theory before and after the ZAMS
    The coexistence of fast and slowly rotating cool stars in ZAMS clusters - forming distinct sequences in the color vs. rotation period plane - is providing clues to differences in their pre main-sequence angular momentum evolution. This Cool Stars 17 splinter was dedicated to a discussion of new observational and theoretical results that may help discriminate between proposed mechanisms for early angular momentum regulation and help us explain the observed ZAMS dichotomy.
  110. Beichman, C., Gelino, C., Kirkpatrick, J., et al., (including Barman, T.), 2013, ApJ, 764, 101, The Coldest Brown Dwarf (or Free-floating Planet)?: The Y Dwarf WISE 1828+2650
    We have monitored the position of the cool Y dwarf WISEPA J182831.08+265037.8 using a combination of ground- and space-based telescopes and have determined its distance to be 11.2+1.3 -1.0 pc. Its absolute H magnitude, MH = 22.21+0.25 -0.22 mag, suggests a mass in the range 0.5-20 M Jup for ages of 0.1-10 Gyr with an effective temperature in the range 250-400 K. The broad range in mass is due primarily to the unknown age of the object. Since the high tangential velocity of the object, 51 5 km s-1, is characteristic of an old disk population, a plausible age range of 2-4 Gyr leads to a mass range of 3-6 M Jup based on fits to the (highly uncertain) COND evolutionary models. The range in temperature is due to the fact that no single model adequately represents the 1-5 m spectral energy distribution (SED) of the source, failing by factors of up to five at either the short or long wavelength portions of the SED. The appearance of this very cold object may be affected by non-equilibrium chemistry or low temperature condensates forming clouds, two atmospheric processes that are known to be important in brown dwarf atmospheres but have proven difficult to model. Finally, we argue that there would have to be a very steep upturn in the number density of late-type Y-dwarfs to account for the putative population of objects suggested by recent microlensing observations. Whether WISE 1828+2650 sits at the low-mass end of the brown dwarf population or is the first example of a large number of "free-floating" planets is not yet known.
  111. Metcalfe, T., Buccino, A., Brown, B., et al., (including Hall, J.), 2013, ApJL, 763, L26, Magnetic Activity Cycles in the Exoplanet Host Star epsilon Eridani
    The active K2 dwarf epsilon Eri has been extensively characterized both as a young solar analog and more recently as an exoplanet host star. As one of the nearest and brightest stars in the sky, it provides an unparalleled opportunity to constrain stellar dynamo theory beyond the Sun. We confirm and document the 3-year magnetic activity cycle in epsilon Eri originally reported by Hatzes and coworkers, and we examine the archival data from previous observations spanning 45 years. The data show coexisting 3-year and 13-year periods leading into a broad activity minimum that resembles a Maunder minimum-like state, followed by the resurgence of a coherent 3-year cycle. The nearly continuous activity record suggests the simultaneous operation of two stellar dynamos with cycle periods of 2.95 0.03 years and 12.7 0.3 years, which, by analogy with the solar case, suggests a revised identification of the dynamo mechanisms that are responsible for the so-called "active" and "inactive" sequences as proposed by Bohm-Vitense. Finally, based on the observed properties of epsilon Eri, we argue that the rotational history of the Sun is what makes it an outlier in the context of magnetic cycles observed in other stars (as also suggested by its Li depletion), and that a Jovian-mass companion cannot be the universal explanation for the solar peculiarities.
  112. Plavchan, P., Anglada-Escud?, G., White, R., et al., (including Prato, L.), 2013, AAS, 221, 109.06, Precision Near-Infrared Radial Velocity Instrumentation and Exoplanet Survey
    We have built and commissioned a gas absorption cell and non-circular core fiber scrambler for precision spectroscopic radial velocity measurements in the near-infrared. We are currently carrying out a pilot survey with the gas cell and the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF) to detect exoplanets around low mass and young stars. We discuss the current status of our survey, with the aim of photon-noise limited radial velocity precision. For adequately bright targets, we are able to probe a noise floor of ~7 m/s with the gas cell with CSHELL at cassegrain focus. Our results demonstrate the feasibility of applying these calibration and illumination stabilization techniques to the next generation of near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at Keck.
  113. Konopacky, Q., Barman, T., Macintosh, B., et al., 2013, AAS, 221, 126.03, 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), favoring a core-accretion process for its formation rather than gravitational instability.
  114. Sanborn, J., Zavala, R., 2013, AAS, 221, 142.07, Close Binaries, Triples, and Eclipses
    Observations of the variable radio source b Per (HR1324) are part of an ongoing survey of close binary systems using the Navy Precision Optical Interferometer. Historical observations of b Per include sparse photometric and spectroscopic observations dating back to 1923, clearly showing this object to be a non-eclipsing, single-lined ellipsoidal variable. This is where the story for b Per stopped until recent inclusion of optical interferometric data which led to the detection of a third, long-period component. As the interferometric observations continue to build up so to is the understanding of this binary system, with the modeled orbital parameters pointing to an edge-on orientation that may allow for the detection of an eclipse by the long-period component. These types of eclipse events are quite rare for long-period binaries due to the nearly edge-on orientation required for their detection, leaving open the opportunity for more traditional methods of observation to add to the body of knowledge concerning this understudied system. Here we present the latest observational data of the b Per system along with an introduction to the best fit orbital parameters governing the eclipsing nature of this complex triple-system.
  115. Ashburn, A., Hunter, D., Rubin, V., 2013, AAS, 221, 146.05, Star Formation in the Extreme Outer Disks of Giant Spiral Galaxies
    We present a photometric study of two galaxies, NGC 801 and UGC 2885, two of the most luminous spiral galaxies in the nearby universe, taking specific interest in the star formation in the outer disks of these galaxies. Our objectives were to find the star formation rate in the outer disks (r>r25) of these two galaxies and to compare our findings to the gas and established models. We used data in the UBV and JHK bands to trace older stars, very deep images in H to trace recent star formation, and HI maps to reveal the atomic gas. We converted the H fluxes to star formation rates as a function of radius, taking into account expected changes in metallicity and reddening with radius. We find that star formation in the outer disks is occurring at a significant rate, even where the gas density is too low to support star formation from gravitational instabilities. We also compare to the empirical star formation law of Bigiel et al. (2010) for lower luminosity spirals.
  116. Crockett, C., Mahmud, N., Prato, L., et al., 2013, AAS, 221, 149.02, Giant Planet Companions to T Tauri Stars
    We present results from an ongoing multiwavelength radial velocity (RV) survey of the Taurus-Auriga star forming region as part of our effort to identify pre-main sequence giant planet hosts. These 1-3 Myr old T Tauri stars present significant challenges to traditional RV surveys. The presence of strong magnetic fields gives rise to large, cool star spots. These spots introduce significant RV jitter which can mimic the velocity modulation from a planet-mass companion. To distinguish between spot-induced and planet-induced RV modulation, we conduct observations at ~6700 A and ~2.3 m and measure the wavelength dependence (if any) in the RV amplitude. CSHELL observations of the known exoplanet host Gl 86 demonstrate our ability to detect not only hot Jupiters in the near infrared but also secular trends from more distant companions. Observations of nine very young stars reveal a typical reduction in RV amplitude at the longer wavelengths by a factor of ~2-3. While we can not confirm the presence of planets in this sample, three targets show different periodicities in the two wavelength regions. This suggests different physical mechanisms underlying the optical and K band variability.
  117. Bowler, B., Liu, M., Shkolnik, E., et al., 2013, AAS, 221, 149.23, The Planets Around Low-Mass Stars (PALMS) Direct Imaging Survey
    Direct imaging is the only method to study the outer architecture (>10 AU) of extrasolar planetary systems in a targeted fashion. Previous imaging surveys have primarily focused on intermediate- and high-mass stars because of the relative dearth of known nearby young M dwarfs. As a result, even though M dwarfs make up 70% of stars in our galaxy, there are few constraints on the population of giant planets at moderate separations (10-100 AU) in this stellar mass regime. We present results from an ongoing high-contrast adaptive optics imaging survey targeting newly identified nearby (<35 pc) young (<300 Myr) M dwarfs with Keck-2/NIRC2 and Subaru/HiCIAO. We have already discovered four young brown dwarf companions with masses between 30-70 Mjup; two of these are members of the ~120 Myr AB Dor moving group, and another one will yield a dynamical mass in the near future. Follow-up optical and near-infrared spectroscopy of these companions reveal spectral types of late-M to early-L and spectroscopic indicators of youth such as angular H-band morphologies, weak J-band alkali lines, and Li absorption and Halpha emission in one target. Altogether our survey is sensitive to planet masses a few times that of Jupiter at separations down to ~10 AU. With a sample size of roughly 80 single M dwarfs, this program represents the deepest and most extensive imaging search for planets around young low-mass stars to date.
  118. Barman, T., Konopacky, Q., Ghez, A., 2013, AAS, 221, 158.23, Testing Atmosphere and Evolution Models with Brown Dwarf Binaries
    Precise dynamical masses are available for many brown dwarf binaries, covering late-M, L and T spectral types. With known masses and equal ages within a binary, the range of predicted luminosity, effective temperature, and surface gravity of each dwarf narrows significantly providing important tests for interior and evolution models. Furthermore, the consistency between the basic properties inferred from evolutionary cooling tracks and those inferred only from atmosphere model comparisons is best tested with brown dwarf binaries. Our recent Hubble Space Telescope program extends the spatially resolved photometric coverage of 11 binaries (all with dynamical masses measured to a precision of 10%, or better) into the optical, allowing precise effective temperatures and bolometric luminosities to be determined. By comparing these new data to models, limits are placed on the brown dwarf cooling evolution across a range of masses. In addition to photometry, ground-based spatially resolved near-IR spectroscopy (obtained with the laser guide star adaptive optics system on the W.M. Keck II telescope and the NIRSPAO spectrograph) is used to estimate surface gravities and further constrain the effective temperatures for a few systems.
  119. Debes, J., Kilic, M., Shkolnik, E., et al., 2013, AAS, 221, 220.01, Teasing out the Subtle Hints of Exo-asteroids Around White Dwarfs with the Magellan White Dwarf Survey
    White dwarfs are unique probes of many phenomena, but recently that have shown remarkable promise in showing observable signatures of planetary systems through the tidal disruption and subsequent accretion of exo-planetesimals. Spectroscopic studies of white dwarfs in the optical and UV are particularly strong probes of the elemental composition of dust from tidally disrupted asteroids perturbed by giant planets. We present initial results with the Magellan White Dwarf Survey, a MIKE echelle spectroscopic campaign that observed 30 white dwarfs with known Ca absorption lines over multiple epochs. The goal of this survey was to monitor metal polluted white dwarfs for changes in accretion, but the summed spectra of this campaign are also useful for abundance analyses of dusty white dwarfs with weaker signatures of accretion as well as determining the origin of metal polluted white dwarfs that show no evidence of dust. We show how high S/N observations of metal polluted white dwarfs can probe cool circumstellar gas in orbit around the white dwarfs that trace evaporated dust that is accreting onto the white dwarf surfaces.
  120. Crossfield, I., Hansen, B., Barman, T., et al., 2013, AAS, 221, 224.01, Exploring the Diversity of Extrasolar Planet Atmospheres
    The detection and characterization of the atmosphere of a habitable, Earthlike planet is a primary goal in the study of extrasolar planets. Until candidates suitable for such characterization are discovered, observations of larger, hotter, and more massive planets must be used to refine observational techniques and inform exoplanetary atmosphere models, while producing new discoveries exciting in their own right. I will present three new results which challenge our current understanding of more massive extrasolar planets, and represent steps toward characterizing future exo-earths. First, I will present new spectrally resolved observations of the extremely hot Jupiter WASP-12b, which has been claimed to be unusually carbon-rich. Our results, which are also the first to correct WASP-12b's emission for the photometric dilution of a nearby M dwarf, strongly disagree with current carbon-rich models and suggests a nearly isothermal planetary photosphere. Thus detailed compositional analysis will rely on transmission spectroscopy rather than emission measurements. Next, our recent survey of 24 micron thermal phase curves of several other nearby hot Jupiters shows that these planets exhibit strikingly dissimilar recirculation of the incident stellar flux. These different heat redistribution patterns (in spite of the planets' similar equilibrium temperatures) demonstrate the continuing challenge of a robust classification scheme for hot Jupiters. Finally, I will also present first results from our observations of the recently discovered warm Uranus GJ 3470b. This planet's bright host star and deep transit make it the best cool, low-mass planet for detailed atmospheric characterization, and it will quickly become a touchstone object in the study of successively smaller, cooler, and more Earthlike planets.
  121. Wood, S., Johnson, M., Hunter, D., et al., 2013, AAS, 221, 242.05, Inside Out: The Stellar Kinematics and HI Map of DDO 46
    This poster will present the optical and radio data for the dwarf galaxy DDO 46. From this information we can hypothesize the three dimensional structure of the galaxy. Through compiling these data, clues to the formation and evolution of dwarf galaxies can be surmised. The optical information was taken with the Mayall 4-meter + Echelle spectrograph at the National Optical Astronomy Observatorys Kitt Peak National Observatory. It was then reduced, which gave one-dimensional spectra of the stars in the disk of DDO 46. These spectra were cross-correlated with nearby radial velocity standard stars within the Milky Way. This method allowed us to derive the stellar velocities and velocity dispersions, z, of DDO 46. The results of the Karl G. Jansky Very Large Array high resolution HI emission data provided integrated intensity and velocity maps that were used to find the maximum rotational velocity, Vmax, of DDO 46. By combining the optical and radio data, we ascertained a kinematic measure, Vmax/z that quantified the three-dimensional shape of the system. The reduced HI radio data observed with the Robert C. Byrd Green Bank Telescope shows the extended, tenuous neutral hydrogen environment around DDO 46, which can potentially reveal recent interactions, mergers, or gas accretion.
  122. Prato, L., 2013, AAS, 221, 251.25, Challenges in the Identification of Young, Low-Mass Spectroscopic Binaries
    Mass is the most fundamental stellar property and with composition determines all aspects of a star's life. However, astronomers' knowledge of pre-main sequence masses and mass ratios is sparse: only ~1-2 dozen masses have been measured, some with relatively poor precision, and only ~50 young, low-mass double-lined systems, for which mass ratio measurements are possible, are known to date. In this poster I report on an effort to double the number of precisely measured mass ratios in young candidate spectroscopic binary systems identified in the literature. This is a first step to ultimately obtaining precise masses for both stars in these systems. High-resolution infrared spectroscopy at the Keck II telescope has revealed that the majority of the putative single-lined spectroscopic binaries observed to date appear to be single stars.
  123. Bowsher, E., Agueros, M., Covey, K., et al., 2013, AAS, 221, 252.07, Deep Imaging of M37, A Better Hyades
    X-ray emission traces the strength of a star's magnetic dynamo and is tightly linked to age and stellar rotation. Early studies found that X-ray luminosity decreases steadily as stars age. However, recent studies suggest that the picture of X-ray luminosity decaying from 10 Myr to 5 Gyr as a single power-law, and independently of mass, is too simplistic. Open clusters, with their homogeneous, coeval populations, provide an ideal environment for calibrating empirically how stellar activity depends on age and rotation. M37, a Hyades analog, has been carefully surveyed in the optical, and we have obtained complementary deep (450 ksec) Chandra ACIS-I imaging of this open cluster. M37's rich membership, good match to Chandra's field-of-view, and large number of measured periods 700) make it ideal for examining the evolution of coronal X-ray emission. Here we report the first results from our analysis of the combined X-ray and optical data. These data will enable determinations of X-ray luminosity as a function of rotation period, tests of whether magnetic effects produce anomalous optical colors/luminosities for high X-ray luminosity sources, and theta characterization of M37's interacting binaries.
  124. Agueros, M., Bochanski, J., Bowsher, E., et al., (including Covey, K.), 2013, AAS, 221, 252.10, The PTF Open Cluster Survey: Tracking the Evolution of Rotation and Activity on the Lower Main Sequence
    A star's age is one of its most fundamental parameters. It is also, for isolated field stars, notoriously difficult to measure. Skumanich (1972) first proposed the existence of a relation between a star's age, rotation, and magnetic activity, but in the intervening 40 years, observational limitations have hampered the assembly of complete and uniform samples of rotation and activity measurements for stars spanning a wide range of ages and masses. We are still far from being able to describe fully the evolution of either rotation or activity for stars of a given mass, or from being able to use rotation or activity measurements to determine precisely the ages of isolated field stars. Fortunately, recent advances have transformed our ability to characterize open clusters, which provide the optimal environment for obtaining robust age estimates for individual stars. Robotic surveys such as the Palomar Transient Factory (PTF) now enable high cadence, long baseline monitoring of large-angular-sized clusters. And multi-object spectrographs and sensitive X-ray detectors make it possible to extend activity measurements to fainter stars in distant, older, and more populous clusters. Here we present recent results from our efforts to assemble a complete, uniform sample of rotation and activity measurements for sub-solar stars in six open clusters ranging in age from 35 Myr to 2.5 Gyr (Alpha Per, the Pleiades, Praesepe, M37, NGC 752, and Ruprecht 147). This sample will be used to derive a description of the age-rotation-activity relation for sub-solar stars from their arrival on the zero-age main-sequence to when they are a significant fraction of the age of the Sun.
  125. Prato, L., 2013, AAS, 221, 255.13, The Lowell Observatory Predoctoral Scholar Program
    Lowell Observatory is pleased to solicit applications for our Predoctoral Scholar Fellowship Program. Now beginning its sixth year, this program is designed to provide unique research opportunities to graduate students in good standing, currently enrolled at Ph.D. granting institutions. Lowell staff research spans a wide range of topics, from astronomical instrumentation, to icy bodies in our solar system, exoplanet science, stellar populations, star formation, and dwarf galaxies. The Observatory's new 4.3 meter Discovery Channel Telescope has successfully seen first light in May, 2012, and is on track to commence science operations in 2013, making this a particularly exciting time in our history. Student research is expected to lead to a thesis dissertation appropriate for graduation at the doctoral level at the student's home institution. The Observatory provides competitive compensation and full benefits to student scholars. For more information, see http://www.lowell.edu/rsch/predoc.php and links therein. Applications for Fall 2013 are due by May 1, 2013.
  126. Johns, P., Prato, L., Greene, T., 2013, AAS, 221, 256.01, Astrophysics of Young Star Binaries in the Taurus Star Forming Region
    This paper describes our studies of the individual components of young star binaries. Most stars are found in multiple systems; thus binaries are important to characterize and understand, both as a common mode for star formation and for their suitability for planet formation. We observed each component in 16 systems, located in the nearby Taurus-Auriga star forming region, using low-resolution (R=760) infrared spectroscopy and photometry. We detected photospheric absorption lines and were able to determine the spectral type, extinction, K-band excess, and luminosity for each component. We estimated the masses and ages by locating each star on the HR Diagram and comparing their positions with theoretical models. The extinction was greater for the secondary components in ~80% of the systems. For two thirds of the systems, the K-band excess of the primary components dominates that of their counterparts. A majority of the systems exhibit Brackett gamma emission at 2.16 microns, which implies that at least one star in these pairs is surrounded by an actively accreting circumstellar disk.
  127. Ruiz, D., Kellogg, K., Prato, L., et al., (including Wasserman, L.), 2013, AAS, 221, 256.05, Young, Low-Mass Spectroscopic Binaries with Unusual Properties
    Young, low-mass spectroscopic binary stars offer the possibility to resolve the orbits and thereby determine the dynamical mass ratio and masses of the components with high accuracy. This is needed to improve evolutionary models for low-mass stars. RX J0513.1+0851, RX J0539.9+0956 and TWA 3A were initially observed as young, low-mass, single-lined spectroscopic binary systems at visible wavelengths. In order to identify these systems as double-lined rather than single-lined, we observed them with high resolution, near-infrared spectroscopy, taken with the Keck II Telescope, applying the power of infrared spectroscopy in the detection of cool secondaries. We used two- dimensional cross-correlation analysis to measure the radial velocities of the individual components and estimate their spectral types, vsini values, and flux ratios. We found that RX J0513.1+0851 and RX J0539.9+0956 are fast rotators, 60 km/s and 80 km/s, respectively; this adds significant difficulty to the detection of the secondary component because of the broad absorption lines. TWA 3A has a vsini of 10 km/s and eccentricity 0.6 this system possesses an actively accreting circumbinary disk, unusual for systems of its age, 10 Myr. We derived the orbital parameters for each system; the mass ratios and orbital periods are q=0.450.02 and 4 days for RX J0513.1+0851, q=0.740.14 and 1119 days for RX J0539.9+0956, and q=0.840.05 and 35 days for TWA 3A. Partial support for this work was provided by NSF grant AST-1009136 (to LP).
  128. Karnath, N., Prato, L., Wasserman, L., et al., 2013, AAS, 221, 256.06, Orbital Parameters for Two Young Spectroscopic Binary Systems
    Orbital parameters for two young, low-mass, pre-main sequence binary systems are described. Originally, VSB 111 and VSB 126 had parameters reported based on single-lined spectroscopic solutions. High-resolution, infrared spectra were obtained with the Keck II telescope on Mauna Kea and used to identify the lines of the secondary stars, yielding double-lined orbital solutions that include the systems' mass ratios. VSB 126 has a period of 12.92470.0001 days, an eccentricity of 0.1840.015, and a mass ratio of 0.270.01. VSB 111 has a period of 901.30621.1792 days, an eccentricity of 0.7910.008, and a mass ratio of 0.600.06. The two systems are located in the ~3 Myr old star forming region NGC 2264, at a distance of ~800 pc. We compare the cluster age and dynamical properties of the stars in these systems with the masses and ages predicted by models of pre-main sequence evolution. Partial support for this work was provided by NSF grant AST-1009136 (to LP).
  129. Covey, K., Wolk, S., Rebull, L., et al., 2013, AAS, 221, 256.07, YSOVAR: The Ceph C Joint Spitzer/Chandra Monitoring Campaign
    The Cepheus C star forming core is the least studied of six CO overdensities identified by Sargent (1977) in their survey of the Cepheus Molecular Cloud complex, which borders the optically revealed Ceph OB3 complex. Observations during Spitzer's cold mission, however, revealed that the Ceph C core hosts >50 YSOs, with a ratio of Class I / Class II sources similar to that of the nearby Rho Ophiuchus star forming region. We have conducted a joint Spitzer/Chandra monitoring program of this young cluster to probe the relationship between X-ray and mid-IR variability in young stars; in particular, we seek to test if stellar X-ray flares can trigger disk instabilities that will be revealed in the source's mid-IR light curve. We present our updated census of cluster members, constructed by supplementing the Spitzer-selected sample with our X-ray selected sample of Class III YSOs, and our initial analysis of the stellar properties and variability characteristics of Ceph C's YSO population, supported by a broad suite of ancillary observations (i.e., ground-based optical & NIR photometry, NIR polarimetric monitoring, moderate resolution [ 3500] NIR spectroscopy & archival data).
  130. Tromp, J., Terebey, S., Angione, J., et al., (including Covey, K.), 2013, AAS, 221, 256.17, Determination of Spectral Types for Candidate Young Stellar Objects in Taurus, L1509, North American Nebula, Ophiuchus North, Perseus, and Orion
    Determining the spectral type of candidate young stellar objects (YSOs) helps confirm their YSO status, and places them on the Hertzsprung-Russell diagram, allowing us to predict their life-cycle. Obtaining spectral types is complicated by dust enshrouding the candidates due to its extinction and reddening of light from the central source, as well as the veiling of the object by excess flux from the protostellar system. We investigate ~100 YSO candidates in six star-forming clouds, Taurus, L1509, North American Nebula, Ophiuchus North, Perseus, and Orion, using near-infrared (NIR) spectroscopy obtained by the Palomar Observatory Triple Spectrograph (Triplespec). We determine spectral type and luminosity class by applying the method described in Covey et al. 2010. This method determines extinction and veiling estimated by JHK magnitudes, and uses equivalent line width ratios in the H and K bands to confirm spectral and luminosity class. Spectral types are derived from these temperature and surface gravity sensitive absorption lines, and then the spectral type is compared to artificially veiled, extincted standards of similar type. A detailed case demonstrating the methodology is presented for a known YSO in Taurus with a presently unknown spectral type, DG Tau B; our results suggest that DG Tau B has late-K spectral type.
  131. Cooper, R., Covey, K., 2013, AAS, 221, 256.20, A Moderate Resolution NIR Spectral Library of Weak-Lined T Tauri Stars
    We present a spectral library of high-quality moderate resolution (R ~ 3500) NIR spectra for 44 weak-lined T Tauri Stars (WTTS) in the Taurus-Auriga Molecular Cloud. These spectra, obtained with the TripleSpec spectrograph on the Astrophysical Research Consortium (ARC) 3.5 meter telescope, provide full coverage of the J, H, and K near-infrared bands in a single epoch. Analyzing these spectra, along with those of dwarf and giant spectral type standards from the SpeX Spectral Library, we have identified several elemental and molecular absorption lines that vary in strength with respect to each star's spectral type and luminosity class. Calibrating each of these features as a spectral type indicator, we provide a detailed characterization for each of the WTTSs in our sample, identifying each star's NIR spectral type and line-of-sight extinction, estimated both from the shape of the overall continuum and from the fluxes of the Paschen beta and Brackett gamma emission lines. In addition to improving our understanding of the properties of these WTTSs, this well characterized spectral library will be a valuable resource for analyses of the NIR continuum veiling and line emission present in the spectra of accreting classical T Tauri stars. This research was made possible by NSF Grant AST-1004107.
  132. Savransky, D., Macintosh, B., Konopacky, Q., et al., (including Barman, T.), 2013, AAS, 221, 343.22, Wavelength-Diversity Derived Low Resolution Spectra of HR8799b
    We present low resolution spectra for HR8799b from data from the OSIRIS integral field spectrograph (IFS) at Keck observatory. These are derived via an advanced method of PSF subtraction that leverages the spectral diversity available in IFS data to generate an optimally compacted decomposition of imaging data [Marois et al., 2010, Soummer et al., 2012]. This method allows for the quantification of overall signal throughput and residual noise variance and enables forward modeling of astrophysical sources. We compare the derived spectra to previously published results, and present a discussion of the algorithm and validation of its performance via recovery of simulated spectra injected into the original data set.
  133. Jensen, A., Redfield, S., Cochran, W., et al., (including Barman, T.), 2013, AAS, 221, 343.24, The Wesleyan Hobby-Eberly High-Resolution Exoplanetary Atmospheric Transmission Spectroscopy Survey: Latest Results
    The Wesleyan Hobby-Eberly High-Resolution Exoplanetary Atmospheric Transmission Spectroscopy Survey (W[HE]2ATS2) has used the 9.2m Hobby-Eberly Telescope (HET) at McDonald Observatory to make observations of the transmission spectra of hot Jupiter atmospheres at high spectral resolution ( 60,000). This program has made the first ground-based detection of neutral sodium in an exoplanetary atmosphere (Redfield et al. 2008) and the first detection of exoplanetary H (Jensen et al. 2012). A primary goal of exoplanet characterization science is to press toward smaller, Earth-like atmospheres. Though such Earth-like atmospheres are largely beyond the reach of current instrumentation, the W[HE]2ATS2 program has obtained data on a hot Neptune-class planet and a highly irradiated hot Jupiter. The purpose of studying a hot Neptune is to explore a planet with a lower surface gravity and possibly a different atmospheric molecular weight and scale height. The goal of observing the irradiated hot Jupiter is to explore the effects of star-planet interactions on exoplanetary atmospheres. Though such a planet is not a precise analogy to Super-Earths or Earth-like planets, there is a great deal of interest in planets around relatively active M dwarf stars, where the habitable zone is much closer to the star and the star-planet interaction may have a great effect on the planets atmosphere. Here we present our initial results for our newest data, where we search for resonance absorption lines of alkali metals such as sodium and potassium, and nonthermally excited material such as n=2 hydrogen detected through H absorption. We also discuss directions for future work with the HET and the W[HE]2ATS2 program. This work is supported by the National Science Foundation through an Astronomy and Astrophysics Research Grant (AST-0903573). The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen.
  134. Hall, J., Levine, S., 2013, AAS, 221, 345.01, First Light from the 4.3-meter Discovery Channel Telescope At Lowell Observatory
    Seven years after groundbreaking on July 12, 2005, the 4.3-meter Discovery Channel Telescope (DCT) is now complete and into commissioning. We obtained first light images in mid 2012 with a 4K x 4K CCD and have recently obtained our first images with the DCT's main camera, the 6K x 6K Large Monolithic Imager (LMI, see adjacent poster by Massey). We held a celebratory gala on July 21, 2012, in Flagstaff. The DCT's delivered image quality is regularly subarcsecond with near-uniform image quality across the FOV from zenith to >2 airmasses, although we have not fully commissioned the active optics system. We attribute this to the outstanding quality of the mirror figures, performed by the University of Arizona's College of Optical Sciences (for M1) and L3 Brashear (for M2). The instrument cube at the RC focus can accommodate four instruments plus the LMI. Designed and built at Lowell Observatory, the cube also contains the DCT's autoguider and wavefront sensor. First light instruments include the 4000 DeVeny spectrograph (the former KPNO White Spectrograph), a low-resolution, high-throughput IR spectrograph, and a higher-resolution IR spectrograph/imager being built by Goddard Space Flight Center in collaboration with the University of Maryland. We are seeking funding for long-slit and fiber-fed echelle spectrographs for higher resolution optical spectroscopy. The DCT can also be configured to host Nasmyth and prime focus instruments. Discovery Communications and its founder John Hendricks contributed $16M to the $53M cost of the telescope, in return for naming rights and first rights to public, educational use of images in their programming. Analysis of data and publication by astronomers in professional journals follows the same procedure as for any other major telescope facility. Discovery's first DCT feature, "Scanning the Skies," aired on September 9, 2012. Future outreach plans include initiating webcasts to classrooms via the Discovery Education networks, reaching 30-40M schoolchildren across the USA. The DCT partner consortium includes Boston University (in perpetuity), the University of Maryland, and the University of Toledo, all of whom have ongoing, long term access to the facility.
  135. Massey, P., Dunham, E., Bida, T., et al., (including Collins, P., Hall, J., Hunter, D., Lauman, S., Levine, S., Neugent, K., Nye, R., Oliver, R., Schleicher, D., Zoonematkermani, S.), 2013, AAS, 221, 345.02, As Big and As Good As It Gets: The Large Monolithic Imager for Lowell Observatory's 4.3-m Discovery Channel Telescope
    The Large Monolithic Imager (LMI), a camera built at Lowell Observatory, is currently undergoing commissioning on Lowell's new 4.3-m Discovery Channel Telescope (DCT). At the heart of the LMI is the largest charge-coupled device (CCD) that can be built using current fabrication techniques, and the first of its kind to be made by e2v. The active area of the chip is 92.2mmx92.4mm, and has 6144 by 6160 15-micron pixels. Our choice of a single chip over a mosaic of smaller ones was inspired by the success of USNO in deploying a similarly ginormous device made by Semiconductor Technology Associates, Inc. There are some significant advantages that a (very!) large single CCD has over a mosaic of smaller ones. With a mosaic, one has to dither to fill in the gaps between the chips for complete areal coverage. This is not only costly in overhead, but it also poses a limitation in faint surface brightness studies, as the sky brightness is constantly changing during the dithering process. In addition, differences in the wavelength dependence of the DQE can lead to differences in the color terms from chip to chip in mosaics, requiring one to deal with each chip as a separate instrument (see the Local Group Galaxy photometry of Massey et al. 2006, AJ, 131, 2478). The LMI avoids these problems. The Discovery Channel Telescope is being built by Lowell Observatory in partnership with Discovery Communications. First light took place in May 2012. Institutional DCT partners include Boston University (in perpetuity), the University of Maryland, and the University of Toledo. More about the DCT can be found in the adjacent poster by Hall et al. The LMI has been made possible thanks to a National Science Foundation grant (AST-1005313). We are currently doing on-sky evaluation of the camera, as commissioning of the DCT progresses, determining color terms, photometric zero-points, astrometric characteristics, etc. We will present these results, along with technical details and many pretty pictures (!), in our poster.
  136. Herzog, M., Massey, P., Morrell, N., et al., (including Neugent, K.), 2013, AAS, 221, 349.29, Getting to Know the Massive Stars within NGC 3603, the Nearest Giant HII Region
    As the closest giant HII region, NGC 3603 offers a rare opportunity to study a dense cluster dominated by very early O-type stars. Previous studies have spectroscopically classified 38 objects ranging from O3 II to B1 I, and several H-rich WN+abs stars. I have been able to classify 50 additional objects from NGC 3603 with recent spectra from the two telescopes Magellan and HST. In addition to spectral classifications, the program FASTWIND was used to model stellar atmospheres for 28 of the objects with observed spectra. The modeled spectra allow for a more accurate assignment of effective temperature and other physical parameters (luminosity, surface gravity, mass-loss rates, etc.) Finally, an H-R diagram was developed using the effective temperatures from the modeled objects and the effective temperatures assigned by spectral class for the non-modeled objects. From this diagram it is possible to compare masses of the observed objects, identify the most massive object and further constrain the age and age spread of NGC 3603. The work was made possible through the Research Experiences for Undergraduates program at Northern Arizona University and Lowell Observatory, which is funded by the National Science Foundation through grant AST-1004107. In addition, support for program GO-11626.01-A was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.
  137. Dirgo, B., van Belle, G., 2013, AAS, 221, 439.11, Linear Sizes from the Palomar Testbed Interferometer Giant Star Survey
    The Palomar Testbed Interferometer (PTI) Giant Star Survey aims to leverage the large body of angular size data available from PTI, previously unpublished. The PTI archive has data for observations of 375 giant stars from PTI taken from 1997 to 2008. We have found a range of diameters of the stars from ~1 to 5.3 milliarcseconds from an initial sample of 64 stars. An average of ~4 stars per spectral type from G8III to M6III show a steady progression from 10 to 100 solar radii. A similar rise in radius correlates with V-K color index from +2 to +6. Outlier objects in these relationships appear to be correlated with poor luminosity classification.
  138. van Belle, G., Paladini, C., Aringer, B., et al., 2013, AAS, 221, 443.03, The PTI Carbon Star Angular Size Survey: Effective Temperatures, Linear Radii, and Oblateness
    We report new interferometric angular diameter observations of 41 carbon stars observed with the Palomar Testbed Interferometer (PTI). Two of these stars are CH carbon stars and represent the first such measurements for this subtype. Of these, 39 have Yamashita (1972, 1975) spectral classes and are of sufficiently high quality that we may determine the dependence of effective temperature on spectral type. We find that there is a tendency for the effective temperature to increase with increasing temperature index by ~120K per step, starting at T_EF 2500K for C3,y. Overall, the median effective temperature for the carbon star sample is found to be 2800+-270K, and the median linear radius is 360+-100 R_sun. We also find agreement on average within 15K with the T_EFF determinations of Bergeat (2001, 2002a,b), and a refinement of carbon star angular size prediction based on V & K magnitudes is presented that is good to an rms of 12%. A subsample of our stars have sufficient {u,v} coverage to permit non-spherical modeling of their photospheres, and a general tendency for detection of statistically significant oblateness with increasing signal-to-noise of the interferometric data is seen. The implications of most carbon stars being spherically oblate is considered in the context of angular moment history and mass loss rates. In particular, compared to the dM/dt rates found in Claussen (1987), a possible correlation between increasing mass loss rates and increasing oblateness is observed.
  139. Palmer, A., van Belle, G., PTI Collaboration, 2013, AAS, 221, 443.04, Supergiant Properties
    The intent of this work is to provide an improved, direct effective temperature calibration for supergiants. By using interferometrically determined angular diameters for 42 Luminosity Class (LC) I and 32 LC II stars from the Palomar Testbed Interferometer, as well as improved photometry, we will improve upon the effective temperatures determined in van Belle et al. (2009). Recent improvements in available archival photometry provide a much richer and more accurate data set than used in the original calculations, augmented by new observational data. For consistency, we utilize the same spectral energy distribution (SED) code and spectral templates to create a more accurate but directly comparable effective temperature calibration. The effective temperature measurement is improved through improved bolometric flux and reddening values that result from the improved photometry constraining the SED fits. Most of our attention is focused on better determination of the reddening values to confirm or rule out any possible bias in the original work. As a secondary comparison, we are exploring any possible relative bias between our interferometric work and Levesque et al.'s (2009) spectroscopic analysis of supergiant effective temperatures, through comparison of the reddening and bolometric flux values.
  140. Clark, R., Carlson, R., Grundy, W., et al., 2013, ASSL, 356, 3, Observed Ices in the Solar System
    No abstract found.
  141. Mastrapa, R., Grundy, W., Gudipati, M., 2013, ASSL, 356, 371, Amorphous and Crystalline H2O-Ice
    No abstract found.

    142. 141 publications and 4464 citations in 2013.

141 publications and 4464 citations total.

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