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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., Benson, J., Bevilacqua, R., Buschmann, T., Clark, J., Ghasempour, A., Hall, J., Hindsley, R., Johnston, K., Jorgensen, A., Mozurkewich, D., Muterspaugh, M., Restaino, S., Shankland, P., Schmitt, H., Tycner, C., van Belle, G., Zavala, R., 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., Holenstein, B., 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. Kiehlmann, S., Savolainen, T., Jorstad, S., Sokolovsky, K., Schinzel, F., Agudo, I., Arkharov, A., Benitez, E., Berdyugin, A., Blinov, D., Bochkarev, N., Borman, G., Burenkov, A., Casadio, C., Doroshenko, V., Efimova, N., Fukazawa, Y., Gomez, J., Hagen-Thorn, V., Heidt, J., Hiriart, D., Itoh, R., Joshi, M., Kimeridze, G., Konstantinova, T., Kopatskaya, E., Korobtsev, I., Kovalev, Y., Krajci, T., Kurtanidze, O., Kurtanidze, S., Larionov, V., Larionova, E., Larionova, L., Lindfors, E., Lopez, E., Marscher, A., McHardy, I., Molina, S., Morozova, D., Nazarov, S., Nikolashvili, M., Nilsson, K., Pulatova, N., Reinthal, R., Sadun, A., Sergeev, S., Sigua, L., Sorcia, M., Spiridonova, O., Takalo, L., Taylor, B., Troitsky, I., Ugolkova, L., Zensus, J., Zhdanova, V., 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.
  5. Harris, H., Dahn, C., Dupuy, T., Canzian, B., Guetter, H., Hartkopf, W., Ireland, M., Leggett, S., Levine, S., Liu, M., Luginbuhl, C., Monet, A., Stone, R., Subasavage, J., Tilleman, T., Walker, R., 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.

  6. Li, J., Kelley, M., Knight, M., Farnham, T., Weaver, H., A'Hearn, M., Mutchler, M., Kolokolova, L., Lamy, P., Toth, I., 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.
  7. 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.
  8. Raiteri, C., Villata, M., D'Ammando, F., Larionov, V., Gurwell, M., Mirzaqulov, D., Smith, P., Acosta-Pulido, J., Agudo, I., Arevalo, M., Bachev, R., Benitez, E., Berdyugin, A., Blinov, D., Borman, G., Bottcher, M., Bozhilov, V., Carnerero, M., Carosati, D., Casadio, C., Chen, W., Doroshenko, V., Efimov, Y., Efimova, N., Ehgamberdiev, S., Gomez, J., Gonzalez-Morales, P., Hiriart, D., Ibryamov, S., Jadhav, Y., Jorstad, S., Joshi, M., Kadenius, V., Klimanov, S., Kohli, M., Konstantinova, T., Kopatskaya, E., Koptelova, E., Kimeridze, G., Kurtanidze, O., Larionova, E., Larionova, L., Ligustri, R., Lindfors, E., Marscher, A., McBreen, B., McHardy, I., Metodieva, Y., Molina, S., Morozova, D., Nazarov, S., Nikolashvili, M., Nilsson, K., Okhmat, D., Ovcharov, E., Panwar, N., Pasanen, M., Peneva, S., Phipps, J., Pulatova, N., Reinthal, R., Ros, J., Sadun, A., Schwartz, R., Semkov, E., Sergeev, S., Sigua, L., Sillanpaa, A., Smith, N., Stoyanov, K., Strigachev, A., Takalo, L., Taylor, B., Thum, C., Troitsky, I., Valcheva, A., Wehrle, A., Wiesemeyer, H., 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.
  9. Karnath, N., Prato, L., Wasserman, L., Torres, G., Skiff, B., Mathieu, R., 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.
  10. 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.
  11. Crossfield, I., Barman, T., Hansen, B., Howard, A., 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

  12. Biller, B., Liu, M., Wahhaj, Z., Nielsen, E., Hayward, T., Males, J., Skemer, A., Close, L., Chun, M., Ftaclas, C., Clarke, F., Thatte, N., Shkolnik, E., Reid, I., Hartung, M., Boss, A., Lin, D., Alencar, S., de Gouveia Dal Pino, E., Gregorio-Hetem, J., Toomey, D., 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).

  13. 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.
  14. Moses, J., Line, M., Visscher, C., Richardson, M., Nettelmann, N., Fortney, J., Barman, T., Stevenson, K., Madhusudhan, N., 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.
  15. 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.
  16. Fares, R., Moutou, C., Donati, J., Catala, C., Shkolnik, E., Jardine, M., Cameron, A., Deleuil, M., 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.
  17. 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.
  18. Nielsen, E., Liu, M., Wahhaj, Z., Biller, B., Hayward, T., Close, L., Males, J., Skemer, A., Chun, M., Ftaclas, C., Alencar, S., Artymowicz, P., Boss, A., Clarke, F., de Gouveia Dal Pino, E., Gregorio-Hetem, J., Hartung, M., Ida, S., Kuchner, M., Lin, D., Reid, I., Shkolnik, E., Tecza, M., Thatte, N., Toomey, D., 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.
  19. Hunter, D., Elmegreen, B., Rubin, V., Ashburn, A., Wright, T., Jozsa, G., Struve, C., 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.
  20. Person, M., Dunham, E., Bosh, A., Levine, S., Gulbis, A., Zangari, A., Zuluaga, C., Pasachoff, J., Babcock, B., Pandey, S., Amrhein, D., Sallum, S., Tholen, D., Collins, P., Bida, T., Taylor, B., Bright, L., Wolf, J., Meyer, A., Pfueller, E., Wiedemann, M., Roeser, H., Lucas, R., Kakkala, M., Ciotti, J., Plunkett, S., Hiraoka, N., Best, W., Pilger, E., Micheli, M., Springmann, A., Hicks, M., Thackeray, B., Emery, J., Tilleman, T., Harris, H., Sheppard, S., Rapoport, S., Ritchie, I., Pearson, M., Mattingly, A., Brimacombe, J., Gault, D., Jones, R., Nolthenius, R., Broughton, J., Barry, T., 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.
  21. Zasowski, G., Johnson, J., Frinchaboy, P., Majewski, S., Nidever, D., Rocha Pinto, H., Girardi, L., Andrews, B., Chojnowski, S., Cudworth, K., Jackson, K., Munn, J., Skrutskie, M., Beaton, R., Blake, C., Covey, K., Deshpande, R., Epstein, C., Fabbian, D., Fleming, S., Garcia Hernandez, D., Herrero, A., Mahadevan, S., Meszaros, S., Schultheis, M., Sellgren, K., Terrien, R., van Saders, J., Allende Prieto, C., Bizyaev, D., Burton, A., Cunha, K., da Costa, L., Hasselquist, S., Hearty, F., Holtzman, J., Garcia Perez, A., Maia, M., O'Connell, R., O'Donnell, C., Pinsonneault, M., Santiago, B., Schiavon, R., Shetrone, M., Smith, V., Wilson, J., 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.
  22. Potter, A., Killen, R., Reardon, K., 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.
  23. Tsang, C., Spencer, J., Lellouch, E., Lopez-Valverde, M., Richter, M., Greathouse, T., 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.
  24. Plavchan, P., Bottom, M., Gao, P., Wallace, J., Mennesson, B., Ciardi, D., Crawford, S., Lin, S., Beichman, C., Brinkworth, C., Johnson, J., Davison, C., White, R., Anglada-Escude, G., von Braun, K., Vasisht, G., Prato, L., Kane, S., Tanner, A., Walp, B., Mills, S., 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.
  25. Plavchan, P., Anglada-Escude, G., White, R., Gao, P., Davison, C., Mills, S., Beichman, C., Brinkworth, C., Johnson, J., Bottom, M., Ciardi, D., Wallace, K., Mennesson, B., von Braun, K., Vasisht, G., Prato, L., Kane, S., Tanner, A., Walp, B., Crawford, S., Lin, S., 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.
  26. Miles, J., Helton, L., Sankrit, R., Andersson, B., Becklin, E., De Buizer, J., Dowell, C., Dunham, E., Gusten, R., Harper, D., Herter, T., Keller, L., Klein, R., Krabbe, A., Marcum, P., McLean, I., Reach, W., Richter, M., Roellig, T., Sandell, G., Savage, M., Smith, E., Temi, P., Vacca, W., Vaillancourt, J., Van Cleve, J., Young, E., Zell, P., 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.
  27. van Belle, G., Paladini, C., Aringer, B., Hron, J., Ciardi, D., 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.
  28. Sanchis-Ojeda, R., Winn, J., Marcy, G., Howard, A., Isaacson, H., Johnson, J., Torres, G., Albrecht, S., Campante, T., Chaplin, W., Davies, G., Lund, M., Carter, J., Dawson, R., Buchhave, L., Everett, M., Fischer, D., Geary, J., Gilliland, R., Horch, E., Howell, S., Latham, D., 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.
  29. Bowler, B., Liu, M., Shkolnik, E., Dupuy, T., 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.

  30. Jorstad, S., Marscher, A., Smith, P., Larionov, V., Agudo, I., Gurwell, M., Wehrle, A., Lahteenmaki, A., Nikolashvili, M., Schmidt, G., Arkharov, A., Blinov, D., Blumenthal, K., Casadio, C., Chigladze, R., Efimova, N., Eggen, J., Gomez, J., Grupe, D., Hagen-Thorn, V., Joshi, M., Kimeridze, G., Konstantinova, T., Kopatskaya, E., Kurtanidze, O., Kurtanidze, S., Larionova, E., Larionova, L., Sigua, L., MacDonald, N., Maune, J., McHardy, I., Miller, H., Molina, S., Morozova, D., Scott, T., Taylor, B., Tornikoski, M., Troitsky, I., Thum, C., Walker, G., Williamson, K., Sallum, S., Consiglio, S., Strelnitski, V., 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.
  31. Wahhaj, Z., Liu, M., Nielsen, E., Biller, B., Hayward, T., Close, L., Males, J., Skemer, A., Ftaclas, C., Chun, M., Thatte, N., Tecza, M., Shkolnik, E., Kuchner, M., Reid, I., de Gouveia Dal Pino, E., Alencar, S., Gregorio-Hetem, J., Boss, A., Lin, D., Toomey, D., 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).

  32. Simon, M., Schaefer, G., Prato, L., 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.
  33. Torres, G., Ruiz-Rodriguez, D., Badenas, M., Prato, L., Schaefer, G., Wasserman, L., Mathieu, R., Latham, D., 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.
  34. Boyajian, T., von Braun, K., van Belle, G., Farrington, C., Schaefer, G., Jones, J., White, R., McAlister, H., ten Brummelaar, T., Ridgway, S., Gies, D., Sturmann, L., Sturmann, J., Turner, N., Goldfinger, P., Vargas, N., 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.
  35. Schaefer, G., Prato, L., Simon, M., Patience, J., 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.
  36. Crossfield, I., Barman, T., Hansen, B., Howard, A., 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.
  37. von Braun, K., Boyajian, T., van Belle, G., Kane, S., Kaltenegger, L., Rugheimer, S., Miguel, Y., Jones, J., Ciardi, D., Lopez-Morales, M., 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.
  38. 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.
  39. 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.
  40. Baines, E., McAlister, H., ten Brummelaar, T., Turner, N., Sturmann, J., Sturmann, L., Farrington, C., Vargas, N., van Belle, G., Ridgway, S., 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.
  41. 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.
  42. Massey, P., Neugent, K., Drout, M., Meynet, G., 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.
  43. Neugent, K., Massey, P., Meynet, G., Georgy, C., 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
  44. Sokal, K., Johnson, K., Indebetouw, R., 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.
  45. Hummel, C., Rivinius, T., Nieva, M., Stahl, O., van Belle, G., Zavala, R., 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).

  46. Covino, E., Esposito, M., Barbieri, M., Mancini, L., Nascimbeni, V., Claudi, R., Desidera, S., Gratton, R., Lanza, A., Sozzetti, A., Biazzo, K., Affer, L., Gandolfi, D., Munari, U., Pagano, I., Bonomo, A., Collier Cameron, A., Hebrard, G., Maggio, A., Messina, S., Micela, G., Molinari, E., Pepe, F., Piotto, G., Ribas, I., Santos, N., Southworth, J., Shkolnik, E., Triaud, A., Bedin, L., Benatti, S., Boccato, C., Bonavita, M., Borsa, F., Borsato, L., Brown, D., Carolo, E., Ciceri, S., Cosentino, R., Damasso, M., Faedi, F., Martinez Fiorenzano, A., Latham, D., Lovis, C., Mordasini, C., Nikolov, N., Poretti, E., Rainer, M., Rebolo Lopez, R., Scandariato, G., Silvotti, R., Smareglia, R., Alcala, J., Cunial, A., Di Fabrizio, L., Di Mauro, M., Giacobbe, P., Granata, V., Harutyunyan, A., Knapic, C., Lattanzi, M., Leto, G., Lodato, G., Malavolta, L., Marzari, F., Molinaro, M., Nardiello, D., Pedani, M., Prisinzano, L., Turrini, D., 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

  47. Desidera, S., Sozzetti, A., Bonomo, A., Gratton, R., Poretti, E., Claudi, R., Latham, D., Affer, L., Cosentino, R., Damasso, M., Esposito, M., Giacobbe, P., Malavolta, L., Nascimbeni, V., Piotto, G., Rainer, M., Scardia, M., Schmid, V., Lanza, A., Micela, G., Pagano, I., Bedin, L., Biazzo, K., Borsa, F., Carolo, E., Covino, E., Faedi, F., Hebrard, G., Lovis, C., Maggio, A., Mancini, L., Marzari, F., Messina, S., Molinari, E., Munari, U., Pepe, F., Santos, N., Scandariato, G., Shkolnik, E., Southworth, J., 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

  48. Ruiz-Rodriguez, D., Prato, L., Torres, G., Wasserman, L., Neuhauser, R., 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.
  49. Richardson, N., Schaefer, G., Gies, D., Chesneau, O., Monnier, J., Baron, F., Che, X., Parks, J., Matson, R., Touhami, Y., Clemens, D., Aldoretta, E., Morrison, N., ten Brummelaar, T., McAlister, H., Kraus, S., Ridgway, S., Sturmann, J., Sturmann, L., Taylor, B., Turner, N., Farrington, C., Goldfinger, P., 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.
  50. 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.
  51. Jacoby, G., Ciardullo, R., De Marco, O., Lee, M., Herrmann, K., Hwang, H., Kaplan, E., Davies, J., 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.
  52. Husser, T., Wende-von Berg, S., Dreizler, S., Homeier, D., Reiners, A., Barman, T., Hauschildt, P., 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.
  53. Grzenia, B., Tycner, C., Jones, C., Rinehart, S., van Belle, G., Sigut, T., 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.
  54. Massey, P., Neugent, K., Hillier, D., Puls, J., 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.
  55. Grundy, W., Olkin, C., Young, L., Buie, M., Young, E., 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.
  56. Crossfield, I., Barman, T., Hansen, B., Tanaka, I., Kodama, T., 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.
  57. Scandariato, G., Maggio, A., Lanza, A., Pagano, I., Fares, R., Shkolnik, E., Bohlender, D., Cameron, A., Dieters, S., Donati, J., Martinez Fiorenzano, A., Jardine, M., Moutou, C., 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.
  58. Parker, A., Buie, M., Osip, D., Gwyn, S., Holman, M., Borncamp, D., Spencer, J., Benecchi, S., Binzel, R., DeMeo, F., Fabbro, S., Fuentes, C., Gay, P., Kavelaars, J., McLeod, B., Petit, J., Sheppard, S., Stern, S., Tholen, D., Trilling, D., Ragozzine, D., Wasserman, L., Ice Hunters, t., 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.
  59. Johnson, J., Shepard, M., Grundy, W., Paige, D., Foote, E., 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.
  60. Elmegreen, B., Rubio, M., Hunter, D., Verdugo, C., Brinks, E., Schruba, A., 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.
  61. Konopacky, Q., Barman, T., Macintosh, B., Marois, C., 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.
  62. 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.

  63. Sahlmann, J., Henning, T., Queloz, D., Quirrenbach, A., Elias, N., Launhardt, R., Pepe, F., Reffert, S., Segransan, D., Setiawan, J., Abuter, R., Andolfato, L., Bizenberger, P., Baumeister, H., Chazelas, B., Delplancke, F., Derie, F., Di Lieto, N., Duc, T., Fleury, M., Graser, U., Kaminski, A., Kohler, R., Leveque, S., Maire, C., Megevand, D., Merand, A., Michellod, Y., Moresmau, J., Mohler, M., Muller, A., Mullhaupt, P., Naranjo, V., Sache, L., Salvade, Y., Schmid, C., Schuhler, N., Schulze-Hartung, T., Sosnowska, D., Tubbs, B., van Belle, G., Wagner, K., Weber, L., Zago, L., Zimmerman, N., 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/).

  64. Hillenbrand, L., Miller, A., Covey, K., Carpenter, J., Cenko, S., Silverman, J., Muirhead, P., Fischer, W., Crepp, J., Bloom, J., Filippenko, A., 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.
  65. 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.
  66. 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.
  67. Lisse, C., Christian, D., Wolk, S., Dennerl, K., Bodewits, D., Combi, M., Lepri, S., Zurbuchen, T., Li, J., Dello-Russo, N., Belton, M., 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.
  68. Bochanski, J., Hawley, S., Covey, K., Agueros, M., Baraffe, I., Catalan, S., Mohanty, S., Rice, E., West, A., 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.
  69. Burgasser, A., Faherty, J., Schmidt, S., West, A., Zapatero Osorio, M., Pineda, J., Burningham, B., Nicholls, C., Sanderson, R., Shkolnik, E., Rodriguez, D., Riedel, A., Joergens, V., 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.
  70. Meibom, S., Barnes, S., Covey, K., Jeffries, R., Matt, S., Morin, J., Palacios, A., Reiners, A., Sicilia-Aguilar, A., Irwin, J., 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.
  71. Beichman, C., Gelino, C., Kirkpatrick, J., Barman, T., Marsh, K., Cushing, M., Wright, E., 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.
  72. Metcalfe, T., Buccino, A., Brown, B., Mathur, S., Soderblom, D., Henry, T., Mauas, P., Petrucci, R., Hall, J., Basu, S., 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.
  73. Clark, R., Carlson, R., Grundy, W., Noll, K., 2013, ASSL, 356, 3, Observed Ices in the Solar System
    No abstract found.
  74. Mastrapa, R., Grundy, W., Gudipati, M., 2013, ASSL, 356, 371, Amorphous and Crystalline H2O-Ice
    No abstract found.

    75. 74 publications and 4452 citations in 2013.

74 publications and 4452 citations total.

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