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Research involving Lowell Observatory staff 2011
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Years: 2011 Bottom

    2011

  1. Cushing, M., Kirkpatrick, J., Gelino, C., et al., (including Prato, L.), 2011, ApJ, 743, 50, The Discovery of Y Dwarfs using Data from the Wide-field Infrared Survey Explorer (WISE)
    We present the discovery of seven ultracool brown dwarfs identified with the Wide-field Infrared Survey Explorer (WISE). Near-infrared spectroscopy reveals deep absorption bands of H2O and CH4 that indicate all seven of the brown dwarfs have spectral types later than UGPS J072227.51-054031.2, the latest-type T dwarf currently known. The spectrum of WISEP J182831.08+265037.8 is distinct in that the heights of the J- and H-band peaks are approximately equal in units of f , so we identify it as the archetypal member of the Y spectral class. The spectra of at least two of the other brown dwarfs exhibit absorption on the blue wing of the H-band peak that we tentatively ascribe to NH3. These spectral morphological changes provide a clear transition between the T dwarfs and the Y dwarfs. In order to produce a smooth near-infrared spectral sequence across the T/Y dwarf transition, we have reclassified UGPS 0722-05 as the T9 spectral standard and tentatively assign WISEP J173835.52+273258.9 as the Y0 spectral standard. In total, six of the seven new brown dwarfs are classified as Y dwarfs: four are classified as Y0, one is classified as Y0 (pec?), and WISEP J1828+2650 is classified as >Y0. We have also compared the spectra to the model atmospheres of Marley and Saumon and infer that the brown dwarfs have effective temperatures ranging from 300 K to 500 K, making them the coldest spectroscopically confirmed brown dwarfs known to date.
  2. Mainzer, A., Grav, T., Bauer, J., et al., (including Wasserman, L.), 2011, ApJ, 743, 156, NEOWISE Observations of Near-Earth Objects: Preliminary Results
    With the NEOWISE portion of the Wide-field Infrared Survey Explorer (WISE) project, we have carried out a highly uniform survey of the near-Earth object (NEO) population at thermal infrared wavelengths ranging from 3 to 22 m, allowing us to refine estimates of their numbers, sizes, and albedos. The NEOWISE survey detected NEOs the same way whether they were previously known or not, subject to the availability of ground-based follow-up observations, resulting in the discovery of more than 130 new NEOs. The survey's uniform sensitivity, observing cadence, and image quality have permitted extrapolation of the 428 near-Earth asteroids (NEAs) detected by NEOWISE during the fully cryogenic portion of the WISE mission to the larger population. We find that there are 981 19 NEAs larger than 1 km and 20,500 3000 NEAs larger than 100 m. We show that the Spaceguard goal of detecting 90% of all 1 km NEAs has been met, and that the cumulative size distribution is best represented by a broken power law with a slope of 1.32 0.14 below 1.5 km. This power-law slope produces ~13, 200 1900 NEAs with D > 140 m. Although previous studies predict another break in the cumulative size distribution below D ~ 50-100 m, resulting in an increase in the number of NEOs in this size range and smaller, we did not detect enough objects to comment on this increase. The overall number for the NEA population between 100 and 1000 m is lower than previous estimates. The numbers of near-Earth comets and potentially hazardous NEOs will be the subject of future work.
  3. Jensen, A., Redfield, S., Endl, M., et al., (including Barman, T.), 2011, ApJ, 743, 203, A Survey of Alkali Line Absorption in Exoplanetary Atmospheres
    We obtained over 90 hr of spectroscopic observations of four exoplanetary systems with the Hobby-Eberly Telescope. Observations were taken in transit and out of transit, and we analyzed the differenced spectrai.e., the transmission spectrato inspect it for absorption at the wavelengths of the neutral sodium (Na I) doublet at 5889, 5895 and neutral potassium (K I) at 7698. We used the transmission spectrum at Ca I 6122which shows strong stellar absorption but is not an alkali metal resonance line that we expect to show significant absorption in these atmospheresas a control line to examine our measurements for systematic errors. We use an empirical Monte Carlo method to quantify these systematic errors. In a reanalysis of the same data set using a reduction and analysis pipeline that was derived independently, we confirm the previously seen Na I absorption in HD 189733b at a level of (- 5.26 1.69) 10-4 (the average value over a 12 A integration band to be consistent with previous authors). Additionally, we tentatively confirm the Na I absorption seen in HD 209458b (independently by multiple authors) at a level of (- 2.63 0.81) 10-4, though the interpretation is less clear. Furthermore, we find Na I absorption of (- 3.16 2.06) 10-4 at <3 in HD 149026b; features apparent in the transmission spectrum are consistent with real absorption and indicate this may be a good target for future observations to confirm. No other results (Na I in HD 147506b and Ca I and K I in all four targets) are significant to >=3, although we observe some features that we argue are primarily artifacts.
  4. Kirkpatrick, J., Cushing, M., Gelino, C., et al., (including Prato, L.), 2011, ApJS, 197, 19, The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
    We present ground-based spectroscopic verification of 6 Y dwarfs (see also Cushing et al.), 89 T dwarfs, 8 L dwarfs, and 1 M dwarf identified by the Wide-field Infrared Survey Explorer (WISE). Eighty of these are cold brown dwarfs with spectral types >=T6, six of which have been announced earlier by Mainzer et al. and Burgasser et al. We present color-color and color-type diagrams showing the locus of M, L, T, and Y dwarfs in WISE color space. Near-infrared and, in a few cases, optical spectra are presented for these discoveries. Near-infrared classifications as late as early Y are presented and objects with peculiar spectra are discussed. Using these new discoveries, we are also able to extend the optical T dwarf classification scheme from T8 to T9. After deriving an absolute WISE 4.6 m (W2) magnitude versus spectral type relation, we estimate spectrophotometric distances to our discoveries. We also use available astrometric measurements to provide preliminary trigonometric parallaxes to four of our discoveries, which have types of L9 pec (red), T8, T9, and Y0; all of these lie within 10 pc of the Sun. The Y0 dwarf, WISE 1541-2250, is the closest at 2.8+1.3 -0.6 pc if this 2.8 pc value persists after continued monitoring, WISE 1541-2250 will become the seventh closest stellar system to the Sun. Another 10 objects, with types between T6 and >Y0, have spectrophotometric distance estimates also placing them within 10 pc. The closest of these, the T6 dwarf WISE 1506+7027, is believed to fall at a distance of ~4.9 pc. WISE multi-epoch positions supplemented with positional info primarily from the Spitzer/Infrared Array Camera allow us to calculate proper motions and tangential velocities for roughly one-half of the new discoveries. This work represents the first step by WISE to complete a full-sky, volume-limited census of late-T and Y dwarfs. Using early results from this census, we present preliminary, lower limits to the space density of these objects and discuss constraints on both the functional form of the mass function and the low-mass limit of star formation.
  5. Blomme, J., Sarro, L., O'Donovan, F., et al., (including Dunham, E., Mandushev, G.), 2011, MNRAS, 418, 96, Improved methodology for the automated classification of periodic variable stars
    We present a novel automated methodology to detect and classify periodic variable stars in a large data base of photometric time series. The methods are based on multivariate Bayesian statistics and use a multistage approach. We applied our method to the ground-based data of the Trans-Atlantic Exoplanet Survey (TrES) Lyr1 field, which is also observed by the Kepler satellite, covering 26 000 stars. We found many eclipsing binaries as well as classical non-radial pulsators, such as slowly pulsating B stars, Doradus, Cephei and Scuti stars. Also a few classical radial pulsators were found.
  6. Adams, E., Lopez-Morales, M., Elliot, J., et al., 2011, ApJ, 741, 102, Twenty-one New Light Curves of OGLE-TR-56b: New System Parameters and Limits on Timing Variations
    Although OGLE-TR-56b was the second transiting exoplanet discovered, only one light curve, observed in 2006, has been published besides the discovery data. We present 21 light curves of 19 different transits observed between 2003 July and 2009 July with the Magellan Telescopes and Gemini South. The combined analysis of the new light curves confirms a slightly inflated planetary radius relative to model predictions, with Rp = 1.378 0.090 RJ . However, the values found for the transit duration, semimajor axis, and inclination values differ significantly from the previous result, likely due to systematic errors. The new semimajor axis and inclination, a = 0.01942 0.00015 AU and i = 73fdg72 0fdg18, are smaller than previously reported, while the total duration, T 14 = 7931 38 s, is 18 minutes longer. The transit midtimes have errors from 23 s to several minutes, and no evidence is seen for transit midtime or duration variations. Similarly, no change is seen in the orbital period, implying a nominal stellar tidal decay factor of Q * = 107, with a 3 lower limit of 105.7.

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

  7. Mandushev, G., Quinn, S., Buchhave, L., et al., (including Dunham, E.), 2011, ApJ, 741, 114, TrES-5: A Massive Jupiter-sized Planet Transiting a Cool G Dwarf
    We report the discovery of TrES-5, a massive hot Jupiter that transits the star GSC 03949-00967 every 1.48 days. From spectroscopy of the star we estimate a stellar effective temperature of T eff = 5171 36 K, and from high-precision B, R, and I photometry of the transit we constrain the ratio of the semimajor axis a and the stellar radius R sstarf to be a/R sstarf = 6.07 0.14. We compare these values to model stellar isochrones to obtain a stellar mass of M sstarf = 0.893 0.024 M . Based on this estimate and the photometric time series, we constrain the stellar radius to be R sstarf = 0.866 0.013 R and the planet radius to be R p = 1.209 0.021 R J. We model our radial-velocity data assuming a circular orbit and find a planetary mass of 1.778 0.063 M J. Our radial-velocity observations rule out line-bisector variations that would indicate a specious detection resulting from a blend of an eclipsing binary system. TrES-5 orbits one of the faintest stars with transiting planets found to date from the ground and demonstrates that precise photometry and followup spectroscopy are possible, albeit challenging, even for such faint stars.
  8. Hunter, D., Zahedy, F., Bowsher, E., et al., 2011, AJ, 142, 173, Mapping the Extended H I Distribution of Three Dwarf Galaxies
    We present large field H I-line emission maps obtained with the single-dish Green Bank Telescope centered on the dwarf irregular galaxies Sextans A, NGC 2366, and WLM. We do not detect the extended skirts of emission associated with the galaxies that were reported from Effelsberg observations. The ratio of H I at 1019 atoms cm-2 to optical extents of these galaxies is instead 2-3, which is normal for this type of galaxy. There is no evidence for a truncation in the H I distribution >=1019 atoms cm-2.
  9. Lissauer, J., Ragozzine, D., Fabrycky, D., et al., (including Dunham, E.), 2011, ApJS, 197, 8, Architecture and Dynamics of Kepler's Candidate Multiple Transiting Planet Systems
    About one-third of the ~1200 transiting planet candidates detected in the first four months of Kepler data are members of multiple candidate systems. There are 115 target stars with two candidate transiting planets, 45 with three, 8 with four, and 1 each with five and six. We characterize the dynamical properties of these candidate multi-planet systems. The distribution of observed period ratios shows that the vast majority of candidate pairs are neither in nor near low-order mean-motion resonances. Nonetheless, there are small but statistically significant excesses of candidate pairs both in resonance and spaced slightly too far apart to be in resonance, particularly near the 2:1 resonance. We find that virtually all candidate systems are stable, as tested by numerical integrations that assume a nominal mass-radius relationship. Several considerations strongly suggest that the vast majority of these multi-candidate systems are true planetary systems. Using the observed multiplicity frequencies, we find that a single population of planetary systems that matches the higher multiplicities underpredicts the number of singly transiting systems. We provide constraints on the true multiplicity and mutual inclination distribution of the multi-candidate systems, revealing a population of systems with multiple super-Earth-size and Neptune-size planets with low to moderate mutual inclinations.
  10. Fressin, F., Torres, G., Desert, J., et al., (including Dunham, E.), 2011, ApJS, 197, 5, Kepler-10 c: a 2.2 Earth Radius Transiting Planet in a Multiple System
    The Kepler mission has recently announced the discovery of Kepler-10 b, the smallest exoplanet discovered to date and the first rocky planet found by the spacecraft. A second, 45 day period transit-like signal present in the photometry from the first eight months of data could not be confirmed as being caused by a planet at the time of that announcement. Here we apply the light curve modeling technique known as BLENDER to explore the possibility that the signal might be due to an astrophysical false positive (blend). To aid in this analysis we report the observation of two transits with the Spitzer Space Telescope at 4.5 m. When combined, they yield a transit depth of 344 85 ppm that is consistent with the depth in the Kepler passband (376 9 ppm, ignoring limb darkening), which rules out blends with an eclipsing binary of a significantly different color than the target. Using these observations along with other constraints from high-resolution imaging and spectroscopy, we are able to exclude the vast majority of possible false positives. We assess the likelihood of the remaining blends, and arrive conservatively at a false alarm rate of 1.6 10-5 that is small enough to validate the candidate as a planet (designated Kepler-10 c) with a very high level of confidence. The radius of this object is measured to be Rp = 2.227+0.052 -0.057 R (in which the error includes the uncertainty in the stellar properties), but currently available radial-velocity measurements only place an upper limit on its mass of about 20 M . Kepler-10 c represents another example (with Kepler-9 d and Kepler-11 g) of statistical "validation" of a transiting exoplanet, as opposed to the usual "confirmation" that can take place when the Doppler signal is detected or transit timing variations are measured. It is anticipated that many of Kepler's smaller candidates will receive a similar treatment since dynamical confirmation may be difficult or impractical with the sensitivity of current instrumentation.
  11. Gilliland, R., Chaplin, W., Dunham, E., et al., 2011, ApJS, 197, 6, Kepler Mission Stellar and Instrument Noise Properties
    Kepler mission results are rapidly contributing to fundamentally new discoveries in both the exoplanet and asteroseismology fields. The data returned from Kepler are unique in terms of the number of stars observed, precision of photometry for time series observations, and the temporal extent of high duty cycle observations. As the first mission to provide extensive time series measurements on thousands of stars over months to years at a level hitherto possible only for the Sun, the results from Kepler will vastly increase our knowledge of stellar variability for quiet solar-type stars. Here, we report on the stellar noise inferred on the timescale of a few hours of most interest for detection of exoplanets via transits. By design the data from moderately bright Kepler stars are expected to have roughly comparable levels of noise intrinsic to the stars and arising from a combination of fundamental limitations such as Poisson statistics and any instrument noise. The noise levels attained by Kepler on-orbit exceed by some 50% the target levels for solar-type, quiet stars. We provide a decomposition of observed noise for an ensemble of 12th magnitude stars arising from fundamental terms (Poisson and readout noise), added noise due to the instrument and that intrinsic to the stars. The largest factor in the modestly higher than anticipated noise follows from intrinsic stellar noise. We show that using stellar parameters from galactic stellar synthesis models, and projections to stellar rotation, activity, and hence noise levels reproduce the primary intrinsic stellar noise features.
  12. Ford, E., Rowe, J., Fabrycky, D., et al., (including Dunham, E.), 2011, ApJS, 197, 2, Transit Timing Observations from Kepler. I. Statistical Analysis of the First Four Months
    The architectures of multiple planet systems can provide valuable constraints on models of planet formation, including orbital migration, and excitation of orbital eccentricities and inclinations. NASA's Kepler mission has identified 1235 transiting planet candidates. The method of transit timing variations (TTVs) has already confirmed seven planets in two planetary systems. We perform a transit timing analysis of the Kepler planet candidates. We find that at least ~11% of planet candidates currently suitable for TTV analysis show evidence suggestive of TTVs, representing at least ~65 TTV candidates. In all cases, the time span of observations must increase for TTVs to provide strong constraints on planet masses and/or orbits, as expected based on N-body integrations of multiple transiting planet candidate systems (assuming circular and coplanar orbits). We find the fraction of planet candidates showing TTVs in this data set does not vary significantly with the number of transiting planet candidates per star, suggesting significant mutual inclinations and that many stars with a single transiting planet should host additional non-transiting planets. We anticipate that Kepler could confirm (or reject) at least ~12 systems with multiple transiting planet candidates via TTVs. Thus, TTVs will provide a powerful tool for confirming transiting planets and characterizing the orbital dynamics of low-mass planets. If Kepler observations were extended to at least seven years, then TTVs would provide much more precise constraints on the dynamics of systems with multiple transiting planets and would become sensitive to planets with orbital periods extending into the habitable zone of solar-type stars.
  13. Buchhave, L., Latham, D., Carter, J., et al., (including Dunham, E.), 2011, ApJS, 197, 3, Kepler-14b: A Massive Hot Jupiter Transiting an F Star in a Close Visual Binary
    We present the discovery of a hot Jupiter transiting an F star in a close visual (0farcs3 sky projected angular separation) binary system. The dilution of the host star's light by the nearly equal magnitude stellar companion (~0.5 mag fainter) significantly affects the derived planetary parameters, and if left uncorrected, leads to an underestimate of the radius and mass of the planet by 10% and 60%, respectively. Other published exoplanets, which have not been observed with high-resolution imaging, could similarly have unresolved stellar companions and thus have incorrectly derived planetary parameters. Kepler-14b (KOI-98) has a period of P = 6.790 days and, correcting for the dilution, has a mass of Mp = 8.40+0.35 - 0.34 M J and a radius of Rp = 1.136+0.073 - 0.054 R J, yielding a mean density of p = 7.1 1.1 g cm-3.
  14. Barman, T., 2011, hst, 12511, Determining the Atmospheric Properties of Directly Imaged Planets
    For the first time, a multi-planet system has been directly imaged. The young star HR 8799 is home to four massive planets {5 to 10 Jupiter-masses} that have all been imaged from the ground, confirmed as proper motion companions, and orbital motion is clearly detected. This system offers a unique opportunity to study planetary atmospheres in detail for a coeval set of objects that also likely have very similar abundances. Despite ground based detections at J, H, K, L, and M-band, there remain significant degeneracies when fitting synthetic spectra to this limited data set. We, therefore, are requesting WFC3 medium band photometric observations from 0.8 to 1.6 microns to better characterize these planets. These proposed data will allow us to distinguish between various atmospheric cloud models and allow robust effective temperature and surface gravity determinations to be made.
  15. Massey, P., 2011, hst, 12528, Probing the Nature of LBVs in M31 and M33: Blasts from the Past
    Luminous Blue Variables {LBVs} are a short-lived, but critical stage in the evolution of the most massive stars. Episodic outbursts during the LBV phase may provide the dominant mass-loss mechanism for evolution to the Wolf-Rayet stage. However, these large mass-loss outbursts {accompanied by large changes in the visual magnitude} take place on timescales of order 1000 years or so: the archetypical LBVs P Cyg and Eta Car had their last major outbursts in the 17th and 19th centuries, respectively. Were these stars located in nearby galaxies would we know of them today? Only six LBVs have been confirmed in M31 and M33 through detection of outbursts, although 175 stars have now been identified as LBV "candidates" in these galaxies. These LBV candidates are spectroscopically indistinguishable from the known LBVs, but no large-scale {>2 mag} photometric outbursts have been found, although many of the candidates do show smaller photometric variability and/or spectroscopic variability. Rather than wait 1000 years for an outburst, we instead here propose to look for signatures of past outbursts in the form of ejecta nebulae close to the stars. The high spatial resolution of STIS will be sensitive to nebulae with radii larger than 0.3-0.4 pc, which corresponds to ages of >500-1000 yrs. These data will allow us to determine the frequency of ejecta among our LBV candidates compared to those of the known LBVs, and determine the physical characteristics of these past mass-loss events. Ultimately, this will help us constrain the lifetime and total mass lost in the LBV phase.
  16. Knight, M., 2011, hst, 12792, High Spatial Resolution Photometric Imaging of the Area Around the Nucleus of C/2011 W3 Lovejoy
    We propose to observe the newly discovered comet C/2011 W3 Lovejoy at one epoch near its closest approach to the Earth in early-January 2012. Lovejoy is a member of the Kreutz group of sungrazing comets and is the first sungrazing comet known to have survived perihelion during the era of modern observations {since 1970}. Its size is currently unconstrained but is critical for understanding Lovejoy?s place in the Kreutz group hierarchy {either as one of the 1600+ known ?pygmy? fragments or one of a handful of major fragments of the parent body, which support and fuel the rest}. Kreutz comets are known to fragment frequently, and we expect that Hubble?s high spatial resolution will reveal individual fragments undetectable by any other means. We will estimate the size distribution of these fragments. Due to Lovejoy?s extreme southern declination, small solar elongation, and 300+ year orbit, these observations can only be obtained using Hubble, and cannot be accomplished at any other epoch.
  17. Porter, S., Grundy, W., 2011, epsc, 2011, 178, KCTF Evolution of Trans-Neptunian Binaries
    Recent observational surveys of Trans-Neptunian Binary (TNB) systems have dramatically increased the number of known mutual orbits. Kozai Cycle Tidal Friction (KCTF) simulations of synthetic binary systems shows that tidal dissipation in these systems can totally reshape their orbits. Specifically, solar torques should have dramatically accelerated the tidal decay and circularization of primordial (or recently excited) TNBs. As a result, an initially random distribution of TNBs will evolve to three distinct populations: extremely tight systems, very low inclination systems, and long-term Kozai oscillators. The tight systems account for approximately one third of evolved systems, while one third to one half are coplanar. These populations appear for a range of TNO physical properties, with stronger gravitational quadrapole minimizing variation due to different physical tidal properties.
  18. Foote, E., Paige, D., Shepard, M., et al., (including Grundy, W.), 2011, epsc, 2011, 329, The Bidirectional Reflectance of Apollo Lunar Soils
    We have compared laboratory solar bidirectional reflectance measurements of a diverse set of Apollo soil samples with Lunar Reconnaissance Orbiter (LRO) Diviner orbital albedo measurements at the Apollo 11 and 16 landing sites. Preliminary results show good agreement between the laboratory and orbital measurements at low phase angles. We expect reasonable agreement between the Apollo 12, 15, and 17 landing sites once we complete those measurements.
  19. French, L., Stephens, R., Lederer, S., et al., (including Wasserman, L.), 2011, epsc, 2011, 351, Preliminary Results from a Rotation Survey of Jovian Trojan Asteroids
    Lightcurve results are presented for 16 Jupiter Trojan asteroids from observations obtained at Cerro Tololo Interamerican Observatory, GMARS Observatory, and Lowell Observatory from October 2009 to January 2011.
  20. Protopapa, S., Boehnhardt, H., Barrera, L., et al., (including Grundy, W.), 2011, epsc, 2011, 512, Longitudinal and temporal variability of Pluto
    In particular, we present low dispersion L band spectroscopy together with high dispersion spectroscopy in H and K bands of Pluto acquired with the NACO instrument at the ESO VLT on 27 June 2008. The nature and properties of the compounds present on the surface of Pluto are investigated by applying a Hapke radiative transfer model to the measured spectra. The 2008 observations are compared with 2005 measurements obtained with the same instrument and spectroscopic mode, covering similar sub-earth longitudes. A systematic study of Pluto's surface composition is presented in order to characterize the spatial and temporal distribution of Pluto's surface ices. The spectra of Pluto obtained at different sub-earth longitudes do not show any significant difference in the wavelength range between 2.9 and 3.7m. No changes in the ratio between pure and diluted methane ice are observed from 2005 to 2008, indicating that Pluto's resurfacing process has slowed down or stopped.
  21. Knight, M., Schleicher, D., 2011, epsc, 2011, 655, Photometry and Imaging of Comet 103P/Hartley 2 from Lowell Observatory
    We will discuss some results based on our imaging and photometric observations of Comet 103P/Hartley 2. Photometry was obtained during the 1991, 1997, and 2010 apparitions. These data reveal a strong secular decrease in production rates from 1991 to 2010 and a strong pre-/post-perihelion asymmetry in 2010. Imaging was obtained over 39 nights from 2010 July through 2011 January and analyses of the data are ongoing. We will discuss the CN coma morphology and make intercomparisons between gas species (CN, OH, C2, and C3), investigate the appearance and behavior of a possible dust jet, and refine the pole solution by combining the published results of multiple authors.
  22. Fuentes, C., Trilling, D., Knight, M., 2011, epsc, 2011, 682, The most dangerous IEOs in STEREO
    IEOs (inner Earth objects or interior Earth objects) are potentially the most dangerous near Earth small body population. Their study is complicated by the fact the population spends all of its time inside the orbit of the Earth, giving ground-based telescopes a small window to observe them. We introduce STEREO (Solar TErrestrial RElations Observatory) and its 5 years of archival data as our best chance of studying the IEO population and discovering possible impactor threats to Earth. We show that in our current search for IEOs in STEREO data we are capable of detecting and characterizing the orbits of 10-100 potentially dangerous IEOs. The number of expected detections by STEREO is based on the current number of known IEOs which is heavily biased by the 8 objects discovered so far [4]. STEREO is sensitive to IEOs that are not visible from the Earth and hence samples a part of the IEO population that has not been discovered yet.
  23. Noll, K., Grundy, W., Benecchi, S., et al., 2011, epsc, 2011, 1029, The Relative Sizes of Transneptunian Binaries: Evidence for Different Populations from a Homogeneous Data Set
    A unique feature of Transneptunian Objects is the prevalence of binaries made up of comparably-sized components. Nearly-equal-brightness binaries are especially common in the low inclination Cold Classicals where all companions differ by mag < 1.5. With the assumption of equal albedos, this translates to secondaries with radii half that of the primary or greater. By contrast, members of the dynamically hot population, Hot Classical, Resonant, and Scattered Disk, have a larger range of secondary sizes. Detection of satellites with magnitude differences of mag > 5, corresponding to secondary radii less than 10% of the primary, are rare. This is explained, in part, by detection biases that limit the detectability of faint secondaries and secondaries that are close to their primary. However, the lack of companions with mag > 1.5 at separations of more than 0.1 arcsec (2900 km at 40 AU), independent of dynamical classification, is strongly constrained with the current data. This limit constrains the overall population of such secondaries.
  24. Grundy, W., Benecchi, S., Buie, M., et al., (including Porter, S., Roe, H.), 2011, epsc, 2011, 1078, A New NOAO Survey Program: Mutual Orbits and Masses of Kuiper Belt Binaries
    We will report progress from our multi-year campaign to determine the orbits and masses of transneptunian binaries (TNBs). Binary systems are abundant in the Kuiper belt, and especially among the "Cold Classical" disk of objects on low-eccentricity, lowinclination, non-resonant orbits about the Sun [1]. These binaries offer an opportunity to learn the masses and densities of an intriguing population of small, distant objects. Additionally, the statistics of their mutual orbital parameters offer clues to conditions where they formed in the protoplanetary nebula, as well as to subsequent dynamical evolution of the outer solar system. Historically, NASA/ESA's Hubble Space Telescope (HST) has been the premier facility for spatially resolving the components of TNBs, benefiting from its exceptionally stable optics and from diffraction- limited imaging unimpeded by the Earth's atmosphere. More recently, laser guide star adaptive optics (LGS AO) technology has enabled large groundbased telescopes to begin contributing valuable data as well [2]. LGS AO observations of faint TNBs (the components of which have typical V magnitudes ~24th) are only feasible when the target passes near an appulse star suitable for use as a tip-tilt correction reference. We have been using LGS AO data from Keck in combination with HST data to constrain TNB orbits [e.g., 3]. In 2011 we began a new 3-year NOAO Survey program to use LGS AO on the 8 m Gemini North telescope. We will discuss how Gemini and other telescopes complement one another, show examples of data from Gemini, Keck, and HST, and describe how we are using these facilities to improve orbital knowledge for as many of the tighter TNBs as we can. Optimal scheduling techniques enable us to make the most efficient possible use of the very limited availability of time on telescopes capable of resolving these objects [4]. Our progress is documented online at http://www.lowell.edu/~grundy/tnbs. We will discuss systems of particular interest such as those likely to undergo mutual events in the near future. These include 2003 QW111 (events probably beginning in a few years) and 79360 1997 CS29 (events probably happening right now). Also of interest are systems for which sizes can be independently determined from thermal or other observations. For these systems, the dynamical masses from binary orbits enable computation of bulk densities. We will also explore statistical patterns beginning to emerge from the growing ensemble of known TNB orbits. Observed distributions of orbital characteristics, including inclinations, eccentricities, and separations have important implications for formation scenarios as well as subsequent evolution [5], although accounting for observational biases remains an open issue. For instance, there appears to be a shortage of loose binaries among TNOs on excited heliocentric orbits. While there seems to be an excess of prograde systems among the tighter binaries, there is little evidence for preferentially low inclinations.
  25. Person, M., Dunham, E., Bida, T., et al., (including Collins, P., Levine, S., Mandushev, G., Taylor, B.), 2011, epsc, 2011, 1374, First Small-Body Occultation Attempts from the Stratospheric Observatory for Infrared Astronomy
    Here we report the first attempts to observe a stellar occultation from the Stratospheric Observatory for Infrared Astronomy. We predicted and will attempt to observe the stellar occultations by Pluto and Charon on 23 June 2011 UT and by Pluto and Hydra on 27 June 2011 UT. We shall provide details on the predictions, preparation, and any successful observations and initial results and implications for the Pluto system.
  26. Zangari, A., Dunham, E., Mandushev, G., et al., (including Collins, P., Bida, T., Taylor, B., Zoonematkermani, S.), 2011, epsc, 2011, 1378, Laboratory precision photometry test results for the High-speed Imaging Photometer for Occultations (HIPO)
    We present the results of several laboratory precision photometry tests using the High-speed Imaging Photometer for Occultations (HIPO), one of seven first generation instruments of the Stratospheric Observatory For Infrared Astronomy (SOFIA). Using artificial stars illuminated by an integrating sphere, we have tested the stability of the photometry in the laboratory against variations in chip temperature, controller temperature, and power supply temperature. We find that changes in the controller temperature and the chip temperature correlate with millimag-level changes in differential photometry and sub-pixel changes in the centroid location of the artificial stars. We find that data can be averaged for up to 10 minutes and 0.1 millimag during times of temperature fluctuations if a single amplifier is used to take data without effecting the results. We make operating recommendations based on the test results and discuss the suitability of HIPO for research beyond occultations, such as exoplanet transits.
  27. Bender, C., Carr, J., Blake, G., et al., (including Barman, T.), 2011, epsc, 2011, 1393, Direct Spectroscopic Characterization of Hot Exoplanet Atmospheres
    We will present current results from our program using high-contrast, high-resolution spectroscopy to directly detect and characterize the atmospheres of short period, hot exoplanets. Our observations target the thermal emission of these planets, and are sensitive to molecules in their atmospheres. We treat these planet+star systems as spectroscopic binaries, and measure the radial velocity of the planet with orbital phase and the planet/star flux ratio at specific bandpasses. These quantities yield a planet's true mass and probe the physics and chemistry of its atmosphere. This technique can directly characterize the large population of non-transiting planets that other surveys are insensitive to.
  28. Roe, H., Greathouse, T., Tokunaga, A., 2011, epsc, 2011, 1398, Update on the TEXES Titan Mid-Infrared Spectral Survey
    At this meeting we will present the current status of the survey, including results on allene (CH2CCH2). We have tentatively identified several of the 10 subbands of allene amongst the strong emission lines of ethane's 12 822 cm-1 band. The observed spectrum of the 845 cm-1 subband are shown in Figure 1. Although often searched for, allene has not previously been detected in Titan's atmosphere. We discuss the challenges of identifying and measuring the abundance of allene when line lists and strengths are often in significant disagreement. In the case of allene a commonly used line list3 predicts significantly stronger emission for the same atmospheric abundance than what is predicted using absorption coefficient spectra empirically derived from cold laboratory spectroscopy. The lack of good line lists and/or high-resolution cold laboratory spectra is a significant obstacle to identifying the many as-yet-unidentified emission lines in the survey's spectra.
  29. Oszkiewicz, D., Bowell, E., Wasserman, L., et al., 2011, epsc, 2011, 1539, Information on asteroid taxonomy contained in phase curves
    We report our findings on asteroid phase curves based on processing large amount of photometric data contained in the Lowell Observatory photometric database [1, 2]. We fitted phase curves [3] to about half a million asteroids contained in the database. We found homogeneity in G12 slope parameters [1] in asteroid families and correlation of G12 with asteroid taxonomic complexes [2]. We predict taxonomic complex preponderance in asteroid families based on G12 slope parameters and compare our results with those available in the literature.
  30. Bowell, E., Oszkiewicz, D., Wasserman, L., et al., (including Muinonen, K.), 2011, epsc, 2011, 1549, Asteroid spin-axis longitudes from the Lowell observatory database
    Using the Lowell Observatory photometric database, we analyze the variation of reduced magnitudes with ecliptic longitude, thereby estimating spin-axis longitudes for hundred of thousands of asteroids. Hitherto, spin-axis longitude estimates have been made for fewer then two hundred asteroids. We investigate longitude distributions in different dynamical groups and longitude preferences in asteroid families. We show that asteroid spin-axis longitudes are not isotropically distributed, as has been suggested by some theoretical studies. For the main belt as a whole, we find a marked depletion of spin-axis longitudes near 140 and excesses near 30 and 90. For Jupiter Trojans there is preponderance of spin axes near 100. We describe longitude distributions for asteroid families.
  31. Bida, T., Killen, R., 2011, epsc, 2011, 1621, Observations of Al, Fe, and Ca+ in Mercury's exosphere
    We report 5- tangent column detections of Al and Fe, and strict 3- tangent column upper limits for Ca+ in Mercury's exosphere obtained using the HIRES spectrometer on the Keck I telescope. These are the first direct detections of Al and Fe in Mercury's exosphere. Our Ca+ observation is consistent with that reported by the The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) on the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft [1].
  32. von Braun, K., Boyajian, T., Turner, N., et al., (including van Belle, G.), 2011, epsc, 2011, 1622, Interferometric Studies of Exoplanet Hosting Stars
    Planetary characterization is playing an increasingly important role in exoplanet research. A frequently overlooked aspect in the calculation of physical quantities of these planets is that they are actually functions of astrophysical parameters of the host stars, such as stellar luminosity or diameter. The value of "understanding the parent stars" cannot be overstated in the realm of assessing the radii of transiting planets, the potential of harboring liquid water on exoplanets (habitable zone), the planetary equilibrium temperatures, etc. We use long-baseline interferometry to provide directly determined stellar astrophysical parameters of exoplanet host stars with the aim of characterizing their planet population. In this presentation, we show the results of our studies of the multiplanet systems GJ 581, GJ 876, and 55 Cancri with planets in or near the respective habitable zones, and of GJ 436 with a transiting hot Neptune.
  33. Buie, M., Tholen, D., Wasserman, L., et al., 2011, epsc, 2011, 1715, Hydra stellar occulatation of 2011 June 27
    We will present details regarding the deployment strategies, prediction efforts, and final results of a stellar occultation by Pluto's outermost satellite, Hydra, that is predicted to occur on 2011 June 27.
  34. Roe, H., Dunham, E., Bida, T., et al., (including Hall, J., Degroff, W.), 2011, epsc, 2011, 1823, A near-infrared spectrograph for the Discovery Channel Telescope
    Lowell Observatory is constructing the Discovery Channel Telescope (DCT) at Happy Jack, Arizona, approximately an hour from Lowell's main campus in Flagstaff, Arizona. The DCT is a 4.3-m optical/ infrared telescope. Construction of the telescope is complete and First Light of the DCT is planned for 2012Q2. In its initial configuration instruments will be co-mounted on a rotatable/selectable cube at the Cassegrain focus. Motorized deployable fold mirrors enable rapid switching amongst instruments. In the future the Nasmyth foci will be available for larger instruments as well. The first generation of instruments on DCT include: the Large Monolithic Imager (LMI), the Near-Infrared High-Throughput Spectrograph (NIHTS, pronounced "nights"), and the DeVeny optical spectrograph. The LMI contains a single large 6.1x6.1 K detector with a 12.5 arcmin2 FOV. NIHTS is a low resolution efficient near-infrared spectrograph and is the subject of this presentation. The DeVeny is Lowell's existing optical spectrograph with resolutions available between 500 and 4000. NIHTS is a low-resolution high-throughput infrared spectrograph covering 0.9-2.4 m in a single fixed spectral setting at a resolution of 100. For simplicity and replicability NIHTS contains no moving parts. The science detector is a 10242 HAWAII-1 array. The fixed slit plate features an 80" long slit with several different slit widths (2,3,4 and 12 pixels) available along its length. The widest slit width is designed to allow accurate flux calibration, while the 3 and 4-pixel slits are closely matched to typical seeing at the DCT site (0.86" mean). Different resolutions will be rapidly selectable by dithering the telescope, and a typical observation is anticipated to involve a sequence of dithers both at the desired resolution and at SED resolution for calibration purposes. Offset guiding and wavefront sensing to control the active optics of the primary mirror are provided by the facility via deployable probes in the instrument cube. Target acquisition and slit-guiding is possible in the optical with the LMI or in the near-infrared with an In- GaAs slit-viewing camera that is part of NIHTS. Because the fold mirror to NIHTS is a dichroic, simultaneous optical imaging with LMI and near-infrared spectroscopy with NIHTS is enabled. NASA funded the construction of NIHTS as part of a larger project, the Kuiper Spectral Survey (KSS), and will be available to all users of the DCT.
  35. Zuluaga, C., Person, M., Bosh, A., et al., (including Levine, S.), 2011, epsc, 2011, 1866, Measured Pluto-Charon Offset from the Stellar Occultations of 23 June 2011
    We report on our Charon results from the double occultation observed on 23 June 2011 [1,2,3]. Our group successfully observed the occultation of the same star, 2UCAC 24677089, by Pluto and Charon shown in Figure 1. Charon occulted the star first, and its shadow was offset from that of Pluto by about 1200 km to the north. Thus, observers on the big island of Hawaii and along most of Baja were in the double-occultation zone, where occultations by both Pluto and Charon could be observed. Observers were located around the globe for this event. In Table 1 we list the sites and instruments used. Using GPStriggered instrument MORIS [4] at the NASA Infrared Telescope Facility (IRTF), we were able to record both occultations within approximately 11 minutes of each other. We obtained Charon-only light curves at an additional three sites. Observations at Leeward Community College on Oahu were made using a GPS-triggered Portable Occultation, Eclipse, and Transit System (POETS [5]). Observers at Table Mountain Observatory (CA) used a GPS-triggered Portable Instrument for Capturing Occultations (PICO [6]). Data were acquired at the U. S. Naval Observatory - Flagstaff Station (AZ) with the USNO Array Camera, an array of six 2k by 4k chips by e2v. We will analyze these data to solve for the shape and size of Charon as well as to how its position relative to Pluto compares to the JPL PLU017 ephemeris.
  36. Raiteri, C., Villata, M., Aller, M., et al., (including Taylor, B.), 2011, A&A, 534, A87, The long-lasting activity of 3C 454.3. GASP-WEBT and satellite observations in 2008-2010
    Context. The blazar 3C 454.3 is one of the most active sources from the radio to the -ray frequencies observed in the past few years.
    Aims: We present multiwavelength observations of this source from April 2008 to March 2010. The radio to optical data are mostly from the GASP-WEBT, UV and X-ray data from Swift, and -ray data from the AGILE and Fermi satellites. The aim is to understand the connection among emissions at different frequencies and to derive information on the emitting jet.
    Methods: Light curves in 18 bands were carefully assembled to study flux variability correlations. We improved the calibration of optical-UV data from the UVOT and OM instruments and estimated the Ly flux to disentangle the contributions from different components in this spectral region.
    Results: The observations reveal prominent variability above 8 GHz. In the optical-UV band, the variability amplitude decreases with increasing frequency due to a steadier radiation from both a broad line region and an accretion disc. The optical flux reaches nearly the same levels in the 2008-2009 and 2009-2010 observing seasons; the mm one shows similar behaviour, whereas the and X-ray flux levels rise in the second period. Two prominent -ray flares in mid 2008 and late 2009 show a double-peaked structure, with a variable /optical flux ratio. The X-ray flux variations seem to follow the -ray and optical ones by about 0.5 and 1 d, respectively.
    Conclusions: We interpret the multifrequency behaviour in terms of an inhomogeneous curved jet, where synchrotron radiation of increasing wavelength is produced in progressively outer and wider jet regions, which can change their orientation in time. In particular, we assume that the long-term variability is due to this geometrical effect. By combining the optical and mm light curves to fit the and X-ray ones, we find that the (X-ray) emission may be explained by inverse-Comptonisation of synchrotron optical (IR) photons by their parent relativistic electrons (SSC process). A slight, variable misalignment between the synchrotron and Comptonisation zones would explain the increased and X-ray flux levels in 2009-2010, as well as the change in the /optical flux ratio during the outbursts peaks. The time delays of the X-ray flux changes after the , and optical ones are consistent with the proposed scenario.

    The radio-to-optical data presented in this paper are stored in the GASP-WEBT archive; for questions regarding their availability, please contact the WEBT President Massimo Villata (villata@oato.inaf.it).Table 3 is available in electronic form at http://www.aanda.org

  37. Hunter, D., Elmegreen, B., Oh, S., et al., (including Massey, P., Wilsey, N., Riabokin, M.), 2011, AJ, 142, 121, The Outer Disks of Dwarf Irregular Galaxies
    In order to explore the properties of extreme outer stellar disks, we obtained ultra-deep V and GALEX ultraviolet (UV) images of four dwarf irregular galaxies and one blue compact dwarf galaxy, and ultra-deep B images of three of these. Our V-band surface photometry extends to 29.5 mag arcsec-2. We convert the FUV and V-band photometry, along with H photometry obtained in a larger survey, into radial star formation rate profiles that are sensitive to timescales from 10 Myr to the lifetime of the galaxy. We also obtained H I-line emission data and compare the stellar distributions, surface brightness profiles, and star formation rate profiles to H I-line emission maps, gas surface density profiles, and gas kinematics. Our data lead us to two general observations. First, the exponential disks in these irregular galaxies are extraordinarily regular. We observe that the stellar disks continue to decline exponentially as far as our measurements extend. In spite of lumpiness in the distribution of young stars and H I distributions and kinematics that have significant unordered motions, sporadic processes that have built the disksstar formation, radial movement of stars, and perhaps even perturbations from the outsidehave, nevertheless, conspired to produce standard disk profiles. Second, there is a remarkable continuity of star formation throughout these disks over time. In four out of five of our galaxies the star formation rate in the outer disk measured from the FUV tracks that determined from the V-band, to within factors of five, requiring star formation at a fairly steady rate over the galaxy's lifetime. Yet, the H I surface density profiles generally decline with radius more shallowly than the stellar light, and the gas is marginally gravitationally stable against collapse into clouds. Outer stellar disks are challenging our concepts of star formation and disk growth and provide a critical environment in which to understand processes that mold galaxy disks.
  38. Galicher, R., Marois, C., Macintosh, B., et al., (including Barman, T.), 2011, ApJL, 739, L41, M-band Imaging of the HR 8799 Planetary System Using an Innovative LOCI-based Background Subtraction Technique
    Multi-wavelength observations/spectroscopy of exoplanetary atmospheres are the basis of the emerging exciting field of comparative exoplanetology. The HR 8799 planetary system is an ideal laboratory to study our current knowledge gap between massive field brown dwarfs and the cold 5 Gyr old solar system planets. The HR 8799 planets have so far been imaged at J- to L-band, with only upper limits available at M-band. We present here deep high-contrast Keck II adaptive optics M-band observations that show the imaging detection of three of the four currently known HR 8799 planets. Such detections were made possible due to the development of an innovative LOCI-based background subtraction scheme that is three times more efficient than a classical median background subtraction for Keck II AO data, representing a gain in telescope time of up to a factor of nine. These M-band detections extend the broadband photometric coverage out to ~5 m and provide access to the strong CO fundamental absorption band at 4.5 m. The new M-band photometry shows that the HR 8799 planets are located near the L/T-type dwarf transition, similar to what was found by other studies. We also confirm that the best atmospheric fits are consistent with low surface gravity, dusty, and non-equilibrium CO/CH4 chemistry models.
  39. Konopacky, Q., Macintosh, B., Fabrycky, D., et al., (including Barman, T.), 2011, ESS, 2, 7.05, Orbital Properties of the HR 8799 Planetary System
    We present a new dynamical analysis of the HR 8799 planetary system. This analysis takes advantage of improved astrometry from all data taken with the Keck II telescope by correcting for biases introduced by the NIRC2 camera's focal plane mask. We now have sufficient time coverage to constrain the orbital properties of these planets independent of stability considerations. We find that the planets cannot have high eccentricities (<0.4) and likely have similar inclinations, implying they formed in a common disk. Applying stability criteria to astrometrically-allowed orbits allows us to put constraints on the masses of these planets. The addition of a fourth planet makes it difficult, if not impossible, to find stable configurations for planetary masses greater than 7 Mjup. This argues that the lower masses predicted for a younger system age ( 30 Myr) are preferred. Using the lessons learned from this analysis, we perform simulations that show that we will be able to successfully constrain the eccentricity distribution of widely separated planets discovered by the upcoming Gemini Planet Imager Exoplanet Survey (GPIES). These constraints will be vital in determining the formation pathways for planets like those in the HR 8799 system.
  40. Redfield, S., Jensen, A., Cochran, W., et al., (including Barman, T.), 2011, ESS, 2, 12.04, Detection of H-alpha Absorption in Exoplanetary Exospheres
    The number of exoplanets with detected atmospheres is rapidly increasing. Particularly intriguing are detections of hydrogen that are attributed to the upper, unbound portion of their atmospheres (i.e., the exospheres) and indicate that some gas giants may be evaporating. Exospheric hydrogen has been detected in Lyman-alpha in the ultraviolet. We present the first detection of hydrogen absorption in H-alpha in the optical, which can be used to study hydrogen level populations and make measurements of the excitation temperature and density of hydrogen in these exospheres. We present a comparative survey of four transiting systems, based on high resolution optical spectra taken with the 9.2 meter Hobby-Eberly Telescope. We clearly detect H-alpha absorption (1.5% over the H-alpha feature) at the 4.6 sigma level for HD189733, and put strong limits on detections in our other systems. These measurements will provide important constraints on models of hydrodynamical atmospheric escape from these planets. Two systems (HD209458 and HD189733) have complementary Lyman-alpha detections. The detection of exospheric absorption in the optical of H-alpha provides a new window into the physical properties of these planetary atmospheres, and ensures access to exospheric measurements even after the end of HST and our capability to acquire UV spectra. This work is supported by the National Science Foundation through an Astronomy and Astrophysics Research Grant (AST-0903573).
  41. Tsvetanov, Z., Olling, R., McCullough, P., et al., (including Mandushev, G.), 2011, ESS, 2, 19.12, Search For Transits Of RV Discovered Planets In The Stereo Data
    We describe an application of the photometric time series extracted from the existing data from one of the instruments on the currently operating space mission STEREO to search for transiting exoplanets.

    STEREO is a mission in NASAs Solar Terrestrial Probes program and uses two nearly identical spacecrafts to map coronal mass ejections as they propagate away from the Sun. In addition to observing the heliosphere STEREO also observes the background star field. The continuous series of images obtained by the Heliospheric Imager 1 (HI-1) cameras on the two STEREO spacecrafts are well suited for the search for transiting exoplanets with bright host stars.

    There are approximately 50 RV-discovered planets in the STEREO field with periods ranging from a few days to several thousand days. This poster will present analysis of the existing data for all of these stars, which consists of up to ten 20-day windows of contiguous coverage of 40 min cadence. The STEREO data provide full coverage for transiting planets with periods up to 20 days and down to a certain radius, dependent on the brightness of the star. We will discuss the limitations in each individual case. In many cases, for the very bright host stars in particular, the transits of even super-Earths could be detected. In addition we will search for transits at the RV established periods. Special attention will be paid to planets with significant eccentricity because of the greatly increased probability of transit. For many of the host stars, the STEREO data provide the most precise photometric time series available; we will quantify the intrinsic variability of those stars in addition to searching for transits.

  42. Jenkins, J., Dunham, E., Argabright, V., et al., 2011, ESS, 2, 19.14, Assessing the Nature and Impact of Observed Stellar Variability on Keplers Ability to Detect Earth-Size Planets
    The Kepler spacecraft was launched on March 6 2009 on a 3.5-year mission to determine the frequency of Earth-size and larger planets in or near the habitable zones of their stars. Kepler has been observing 160,000 stars to detect transiting planets for over two years and has discovered more than 16 confirmed or validated planets and has identified over 1200 candidate planets. There is sufficient data and experience with the photometer to characterize Keplers ability to detect weak signatures of small, terrestrial planets. The photometers sensitivity depends on the total combined differential photometric precision (CDPP) and on the mission lifetime. These driving requirements for Kepler called for a total CDPP of 20 ppm for 12th magnitude G2 dwarf stars in 6.5 hours, and a mission lifetime of 3.5 years. The noise budget includes 14 ppm for shot noise, 10 ppm for instrument noise and 10 ppm adopted for intrinsic stellar variability. The CDPP requirement was necessarily set without knowledge of actual typical levels of stellar variability. We find that Keplers noise metrics for 12th magnitude dwarf stars are dominated by stellar variability and the overall combined noise is 50% higher than the required value. While this does reduce Keplers ability to achieve its scientific objectives, Keplers originally envisioned capability to detect terrestrial planets can be recovered by extending the duration of the flight mission to 8 years.
  43. Vigan, A., Patience, J., Galicher, R., et al., (including Barman, T.), 2011, ESS, 2, 22.02, Initial Results From The AO International Deep Planet Search Around Young A Stars
    Throughout their evolution, A stars exhibit favorable physical conditions and indirect evidence of planet formation, such as extended protoplanetary disks at the pre-main sequence stage and debris disks in the main sequence phase. Recent breakthrough discoveries of planetary companions around young, dusty A stars have identified the first massive planets at wide orbital separation. In order to understand the frequency of such systems -- an important factor for formation scenarios -- we are conducting a near-infrared adaptive optics search for giant planets around nearby A stars, part the on-going International Deep Planet Search (IDPS). We present the preliminary results of this survey of 40 stars: 28 of them are nearby (<65 pc) young (<200 Myr) A stars, and the others are star identified as extremely young (<20 Myr) from spectral analysis. The observations were obtained with 8 meter-class telescopes (VLT and Gemini). The Locally Optimized Combination of Images (LOCI) was used to suppress the speckle noise of the central star and reach the detection level of giant planets and low-mass brown dwarfs at wide orbital separation. The median 5-sigma sensitivity of our observations is 9.5 mag at 0.5 arcseconds and 14 mag at separations of a few arcseconds, allowing us to reach limits 1 to 20 Mjup, depending on the target mass and age. We present an overview of the observations, data analysis and performance, followed by a statistical analysis of the survey results, which provide upper limits on the fractions of stars with giant planet and low mass brown dwarf companions.
  44. Crossfield, I., Hansen, B., Barman, T., 2011, ESS, 2, 40.08, A Ground-based, Near-infrared, Emission Spectrum Of WASP-12b
    We report our measurement of the emission spectrum of the Hot Jupiter WASP-12b. We observed two secondary eclipses with SpeX on the NASA IRTF (covering the H and K bands at low resolution) and recover consistent planetary spectra from both events. We discuss our

    results, which are consistent with recent CFHT/WIRCam ground-based

    photometry but suggest a somewhat different spectral slope than

    inferred from those and Spitzer/IRAC data. In general, we find the

    ability of single-slit spectrographs to characterize exoplanet

    atmospheres is ultimately limited by our inability to sufficiently

    characterize temporal evolution of telluric and instrumental

    systematics. We discuss our possibilities and limitations in the

    context of our ongoing efforts to perform ground-based exoplanet

    spectroscopy, and reiterate the exciting, transformative potential of

    near-infrared multi-object spectrographs to revolutionize this field.

  45. King, R., Patience, J., De Rosa, R., et al., (including Barman, T.), 2011, ESS, 2, 40.16, The Atmospheres and Evolution of Young Brown Dwarf/Planetary-Mass Companions
    We present VLT\SINFONI JHK spectra of a set of young, low-mass brown dwarf and planetary-mass companions and a comparison with more evolved substellar companions and several theoretical model atmospheres. In the study of cool atmospheres, these low-mass companions to nearby young stars are particularly valuable since the primary provides constraints on the distance to and age of these low-mass objects, breaking the mass-age-luminosity degeneracy. Our sample consists of the lowest mass imaged companions with ages of 2-30 Myr and estimated masses of 5-25 MJup. These companions represent the lowest mass objects in the 2-30 Myr age range for which it is possible to obtain high quality infrared spectra. A particularly interesting member of the sample is 2M1207b, a young L dwarf with an anomalously low luminosity. We explore possible scenarios to explain its observed spectrum.
  46. von Braun, K., Krick, J., Ingalls, J., et al., (including van Belle, G.), 2011, ESS, 2, 40.24, A Comparative Study of the Atmospheres of Transiting Exoplanets
    Spitzer's extended warm mission gives us the opportunity to perform comparative studies of exoplanets' atmospheres. We describe the techniques and methods involved in our recently accepted Spitzer Exploration Science Proposal (Proposal ID 80016; PI: J. Krick; 619 hours) to obtain high-precision 4.5 micron phase curves for 22 transiting hot Jupiter systems, along with observations of secondary eclipses of 7 of these systems. The principal goal of this study, which will quadruple the number of phase curve observations to date, is to map longitudinal temperature distribution of the planetary atmospheres and to assess the following questions: (1) What is the contrast between exoplanetary day- and nightside temperatures, i. e., how efficiently is the incident energy redistributed? (2) Are the weather phenomena in the exoplanetary atmospheres stable over long periods of time? (3) How do the temperature distributions on the planetary surfaces correlate with astrophysical properties of the star-planet systems? To answer these questions with our proposed Spitzer observations, we will employ a novel observing technique involving snapshot observing to reduce telescope time requirements, and PCRS peak-up to IRAC to increase the pointing accuracy and thus minimize the photometric error due to intrapixel sensitivity variation.
  47. Doyle, L., Carter, J., Fabrycky, D., et al., (including Dunham, E.), 2011, Sci, 333, 1602, Kepler-16: A Transiting Circumbinary Planet
    We report the detection of a planet whose orbit surrounds a pair of low-mass stars. Data from the Kepler spacecraft reveal transits of the planet across both stars, in addition to the mutual eclipses of the stars, giving precise constraints on the absolute dimensions of all three bodies. The planet is comparable to Saturn in mass and size and is on a nearly circular 229-day orbit around its two parent stars. The eclipsing stars are 20 and 69% as massive as the Sun and have an eccentric 41-day orbit. The motions of all three bodies are confined to within 0.5 of a single plane, suggesting that the planet formed within a circumbinary disk.
  48. Anderson, D., Smith, A., Lanotte, A., et al., (including Barman, T.), 2011, MNRAS, 416, 2108, Thermal emission at 4.5 and 8 m of WASP-17b, an extremely large planet in a slightly eccentric orbit
    We report the detection of thermal emission at 4.5 and 8 m from the planet WASP-17b. We used Spitzer to measure the system brightness at each wavelength during two occultations of the planet by its host star. By combining the resulting light curves with existing transit light curves and radial-velocity measurements in a simultaneous analysis, we find the radius of WASP-17b to be 2.0RJup, which is 0.2RJup larger than any other known planet and 0.7RJup larger than predicted by the standard cooling theory of irradiated gas giant planets. We find the retrograde orbit of WASP-17b to be slightly eccentric, with 0.0012 < e < 0.070 (3). Such a low eccentricity suggests that, under current models, tidal heating alone could not have bloated the planet to its current size, so the radius of WASP-17b is currently unexplained. From the measured planet-star flux-density ratios we infer 4.5 and 8 m brightness temperatures of 1881 50 and 1580 150 K, respectively, consistent with a low-albedo planet that efficiently redistributes heat from its day side to its night side.
  49. Dalle Ore, C., Fulchignoni, M., Cruikshank, D., et al., (including Grundy, W.), 2011, A&A, 533, A98, Organic materials in planetary and protoplanetary systems: nature or nurture?

    Aims: The objective of this work is to summarize the discussion of a workshop aimed at investigating the properties, origins, and evolution of the materials that are responsible for the red coloration of the small objects in the outer parts of the solar system. Because of limitations or inconsistencies in the observations and, until recently, the limited availability of laboratory data, there are still many questions on the subject. Our goal is to approach two of the main questions in a systematic way: - Is coloring an original signature of materials that are presolar in origin ("nature") or stems from post-formational chemical alteration, or weathering ("nurture")? - What is the chemical signature of the material that causes spectra to be sloped towards the red in the visible? We examine evidence available both from the laboratory and from observations sampling different parts of the solar system and circumstellar regions (disks).
    Methods: We present a compilation of brief summaries gathered during the workshop and describe the evidence towards a primordial vs. evolutionary origin for the material that reddens the small objects in the outer parts of our, as well as in other, planetary systems. We proceed by first summarizing laboratory results followed by observational data collected at various distances from the Sun.
    Results: While laboratory experiments show clear evidence of irradiation effects, particularly from ion bombardment, the first obstacle often resides in the ability to unequivocally identify the organic material in the observations. The lack of extended spectral data of good quality and resolution is at the base of this problem. Furthermore, that both mechanisms, weathering and presolar, act on the icy materials in a spectroscopically indistinguishable way makes our goal of defining the impact of each mechanism challenging.
    Conclusions: Through a review of some of the workshop presentations and discussions, encompassing laboratory experiments as well as observational data, we infer that both "nature" and "nurture" are instrumental in the coloration of small objects in the outer parts
  50. Heesen, V., Rau, U., Rupen, M., et al., (including Hunter, D.), 2011, ApJL, 739, L23, Deep Radio Continuum Imaging of the Dwarf Irregular Galaxy IC 10: Tracing Star Formation and Magnetic Fields
    We exploit the vastly increased sensitivity of the Expanded Very Large Array to study the radio continuum and polarization properties of the post-starburst, dwarf irregular galaxy IC 10 at 6 cm, at a linear resolution of ~50 pc. We find close agreement between radio continuum and H emission, from the brightest H II regions to the weaker emission in the disk. A quantitative analysis shows a strictly linear correlation, where the thermal component contributes 50% to the total radio emission, the remainder being due to a non-thermal component with a surprisingly steep radio spectral index of between -0.7 and -1.0 suggesting substantial radiation losses of the cosmic-ray electrons. We confirm and clearly resolve polarized emission at the 10%-20% level associated with a non-thermal superbubble, where the ordered magnetic field is possibly enhanced due to the compression of the expanding bubble. A fraction of the cosmic-ray electrons has likely escaped because the measured radio emission is a factor of three lower than what is suggested by the H-inferred star formation rate.
  51. Bianchi, L., Kang, Y., Efremova, B., et al., (including Massey, P.), 2011, Ap&SS, 335, 249, Young stellar populations in the local group: an HST and GALEX comprehensive study
    The study of the stellar constituents of star-forming sites in a wide variety of conditions yields the key to interpreting wide-field UV-optical imaging of extended nearby galaxies, and of distant galaxies. We obtained six-band imaging (from far-UV to I) with HST-WFPC2 of 67 sites of recent star formation in eight Local Group galaxies. HST pointings were selected from GALEX wide-field FUV imaging, which traces the young stellar populations. The HST observations were optimized to characterize the hottest, most massive stars in these regions. From the HST photometry, analyzed with stellar model colors, we derived the physical parameters of the massive stars in each field, and of the extinction by interstellar dust. The HST results are used to interpret GALEX UV measurements of SF across the entire galaxies. Our comprehensive photometric study at HST resolution (sub-pc scale in these galaxies) also provides an ideal selection of targets for follow-up spectroscopy with large ground-based telescopes, and in the UV with HST- or WSO-class telescopes, to clarify the influence of metallicity on the properties and the evolution of massive stars.
  52. Simpson, C., Hunter, D., Nordgren, T., et al., 2011, AJ, 142, 82, VII Zw 403: H I Structure in a Blue Compact Dwarf Galaxy
    We present optical (UBVJ), ultraviolet (FUV, NUV), and high-resolution atomic hydrogen (H I) observations of the nearby blue compact dwarf (BCD), VII Zw 403. We find that VII Zw 403 has a relatively high H I mass-to-light ratio for a BCD. The rotation velocity is nominally 10-15 km s-1, but rises to ~20 km s-1 after correction for the ~8-10 km s-1 random motions present in the gas. The velocity field is complex, including a variation in the position angle of the major axis going from the northeast to the southwest parts of the galaxy. Our high-resolution H I maps reveal structure in the central gas, including a large, low-density H I depression or hole between the southern and northern halves of the galaxy, coincident with an unresolved X-ray source. Although interactions have been proposed as the triggering mechanism for the vigorous star formation occurring in BCDs, VII Zw 403 does not seem to have been tidally triggered by an external interaction, as we have found no nearby possible perturbers. It also does not appear to fall in the set of galaxies that exhibit a strong central mass density concentration, as its optical scale length is large in comparison to similar systems. However, there are some features that are compatible with an accretion event: optical/H I axis misalignment, a change in position angle of the kinematic axis, and a complex velocity field.
  53. Roe, H., Schaller, E., Brown, M., et al., 2011, noao, 35, Titan's Methane Weather post-Equinox: Seasonal climate change and surface geology
    Recently in this program we discovered clouds in the north polar region that are formed via lake-effect processes (Brown et al. 2008) and observed a massive tropical storm that induced Rossby-wave clouds throughout the southern hemisphere (Schaller et al. 2009). Previously we discovered Titan's mid-latitude clouds (Roe et al. 2005a) and that their locations are controlled by surface processes, possibly including cryovolcanoes, geysering, and/or the opening of surface cracks (Roe et al. 2005b). We observed a massive storm engulfing the south pole (Schaller et al. 2006a) and found a near-disappearance of south polar cloud activity as the season moved further into southern summer (Schaller et al. 2006B). Observing Titan's clouds requires only a small amount (15-25 min) of large (8-10 meter) adaptive optics telescope time and queued Gemini observations are uniquely suited to this program. As Titan's northern spring progresses (equinox was in August 2009), continued observations are required to monitor the advance of the planetary scale monsoon, driving new clouds in the northern and southern polar regions, and identify and monitor regions of active surface geology.
  54. Naud, M., Artigau, E., Malo, L., et al., (including Barman, T.), 2011, noao, 321, A Planet Search around Young-associations M dwarfs (PSYM survey)
    A comprehensive investigation of the formation and evolution of giant planets requires a thorough direct imaging search for planets around primaries of all masses. Currently, as published direct imaging surveys have been biased towards solar-type or more massive primaries, and since relatively few nearby young low-mass stars were known, these stars are under-represented in the sample targeted by previous searches. Using a new Bayesian analysis that takes into account proper motion, sky position, chromospheric activity (Halpha and X-ray), photometry and radial-velocity, we have identified 145 new low mass (>K7) members of nearby young (<50 Myr) associations. Being young and nearby, these newly-identified members are ideal targets for direct imaging searches. Here, we propose to continue our survey of this sample of new low-mass stars with NICI to search for self-luminous giant planets down to 2 Mjup at orbital separations of 15-500 AU. Our survey will nearly quadruple the number of young M-dwarfs probed for planets and will allow, for the first time, to place constraints on the existence of planets around low-mass stars at a level comparable to what has been done for more massive stars. A companion proposal, PSYM-wide, will complete our survey for the 300-5000 AU orbital range.
  55. Meibom, S., Barnes, S., Geller, A., et al., 2011, noao, 323, The connections between binarity, circumstellar disks, and stellar rotation
    We propose to study the effect on stellar rotation of binary companions within the typical circumstellar disk radius ( 100 AU), but beyond the reach of tidal interactions ( 0.2 AU). A first hint of faster rotation among binary primary stars than among single stars has been detected in the ~150 Myr open cluster M35 (tidally synchronized binaries excluded). This result is consistent with a model scenario involving truncation of the mass, size, and lifetime of the circumstellar disk by a companion, and consequently a shortened phase of magnetic disk-braking of the stellar rotation during the PMS phase. The scenario suggests the hypothesis that a difference in rotation between single and binary primary stars should be more pronounced in younger stellar populations, and gradually disappear over time as magnetic winds spin down stars not tidally locked. We propose to test this hypothesis by conducting a multi-epoch radial-velocity survey for membership and binarity in the rich 540 Myr open cluster M37, for which a unique set of rotational data ( 500 rotation periods) is available for late-type photometric members.
  56. Zhang, H., Hunter, D., Herrmann, K., et al., 2011, noao, 379, Deep JH Imaging of the LITTLE THINGS Galaxies: Stellar Mass Assembly in Dwarf Galaxies
    We propose to obtain deep broadband JH images for 2 dwarf irregular galaxies (dIm) which are part of a larger sample assembled by the LITTLE THINGS project (a VLA Large Proposal). Using the NIR data requested here and other multi-band data we have collected, we will, for the first time, construct high-quality spectral energy distributions (SEDs) covering the whole spectral range of stellar emission for a representative sample of dIm galaxies. dIm galaxies numerically dominate the local universe, yet our understanding of the star formation processes in dIm galaxies is very poor. For example, the star formation rate profile often correlates closely with the stellar surface brightness profile of the older stars, but not with the gas, and we do not know why. Also, abrupt changes in the slope of the stellar exponential profile imply a change in the star formation process at the surface brightness breaks according to some models, but this has not been shown observationally. With the SEDs constructed as a function of radius within each galaxy and our stellar population synthesis technique, we will answer the questions: 1) How is the stellar mass across the disks assembled throughout the lifetime of dwarf irregular galaxies? 2) Are there corresponding surface mass density breaks at the surface brightness breaks seen in many dIm galaxies? 3) Is there any difference in the stellar populations before and beyond the surface brightness breaks?
  57. French, L., Stephens, R., Wasserman, L., et al., 2011, noao, 495, Rotation Studies of Jovian Trojan Asteroids
    The Jovian Trojan asteroids appear to be fundamentally different from main belt asteroids. They formed further from the sun, they are of different composition, and their collisional history is different. Lightcurve studies provide information about the distribution of rotation frequencies of a group of asteroids. For main belt asteroids larger than about 40 km in diameter, the distribution of rotation frequencies is Maxwellian (Pravec et al. 2000). This suggests that collisions determine their rotation properties. Smaller main belt asteroids, however, show a predominance of both fast and slow rotators, with the observed spin distribution apparently controlled by the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect (Pravec et al. 2008). The Trojans larger than 100 km in diameter have been almost completely sampled, but lightcurves for smaller Trojans have been less well studied due to their low albedos and greater solar distances. We propose to investigate the rotation periods of 4-6 small (D < 50 km) Trojan asteroids and 6-9 Trojans in the 50-100 km size range.
  58. Sanchez-Lavega, A., Orton, G., Hueso, R., et al., (including Grundy, W.), 2011, Icar, 214, 462, Long-term evolution of the aerosol debris cloud produced by the 2009 impact on Jupiter
    We present a study of the long-term evolution of the cloud of aerosols produced in the atmosphere of Jupiter by the impact of an object on 19 July 2009 (Sanchez-Lavega, A. et al. [2010]. Astrophys. J. 715, L155-L159). The work is based on images obtained during 5 months from the impact to 31 December 2009 taken in visible continuum wavelengths and from 20 July 2009 to 28 May 2010 taken in near-infrared deep hydrogen-methane absorption bands at 2.1-2.3 m. The impact cloud expanded zonally from 5000 km (July 19) to 225,000 km (29 October, about 180 in longitude), remaining meridionally localized within a latitude band from 53.5S to 61.5S planetographic latitude. During the first two months after its formation the site showed heterogeneous structure with 500-1000 km sized embedded spots. Later the reflectivity of the debris field became more homogeneous due to clump mergers. The cloud was mainly dispersed in longitude by the dominant zonal winds and their meridional shear, during the initial stages, localized motions may have been induced by thermal perturbation caused by the impact's energy deposition. The tracking of individual spots within the impact cloud shows that the westward jet at 56.5S latitude increases its eastward velocity with altitude above the tropopause by 5-10 m s -1. The corresponding vertical wind shear is low, about 1 m s -1 per scale height in agreement with previous thermal wind estimations. We found evidence for discrete localized meridional motions with speeds of 1-2 m s -1. Two numerical models are used to simulate the observed cloud dispersion. One is a pure advection of the aerosols by the winds and their shears. The other uses the EPIC code, a nonlinear calculation of the evolution of the potential vorticity field generated by a heat pulse that simulates the impact. Both models reproduce the observed global structure of the cloud and the dominant zonal dispersion of the aerosols, but not the details of the cloud morphology. The reflectivity of the impact cloud decreased exponentially with a characteristic timescale of 15 days; we can explain this behavior with a radiative transfer model of the cloud optical depth coupled to an advection model of the cloud dispersion by the wind shears. The expected sedimentation time in the stratosphere (altitude levels 5-100 mbar) for the small aerosol particles forming the cloud is 45-200 days, thus aerosols were removed vertically over the long term following their zonal dispersion. No evidence of the cloud was detected 10 months after the impact.
  59. Lellouch, E., Stansberry, J., Emery, J., et al., (including Grundy, W.), 2011, Icar, 214, 701, Thermal properties of Pluto's and Charon's surfaces from Spitzer observations
    We report on thermal observations of the Pluto-Charon system acquired by the Spitzer observatory in August-September 2004. The observations, which consist of (i) photometric measurements (8 visits) with the Multiband Imaging Photometer (MIPS) at 24, 70 and 160 m and (ii) low-resolution spectra (8 visits) over 20-37 m with the Infrared Spectrometer (IRS), clearly exhibit the thermal lightcurve of Pluto/Charon at a variety of wavelengths. They further indicate a steady decrease of the system brightness temperature with increasing wavelength. Observations are analyzed by means of a thermophysical model, including the effects of thermal conduction and surface roughness, and using a multi-terrain description of Pluto and Charon surfaces in accordance with visible imaging and lightcurves, and visible and near-infrared spectroscopy. Three units are considered for Pluto, respectively covered by N 2 ice, CH 4 ice, and a tholin/H 2O mix. Essential model parameters are the thermal inertia of Pluto and Charon surfaces and the spectral and bolometric emissivity of the various units. A new and improved value of Pluto's surface thermal inertia, referring to the CH 4 and tholin/H 2O areas, is determined to be Pl = 20-30 J m -2 s -1/2 K -1 (MKS). The high-quality 24-m lightcurve permits a precise assessment of Charon's thermal emission, indicating a mean surface temperature of 55.4 2.6 K. Although Charon is on average warmer than Pluto, it is also not in instantaneous equilibrium with solar radiation. Charon's surface thermal inertia is in the range Ch = 10-150 MKS, though most model solutions point to Ch = 10-20 MKS. Pluto and Charon thermal inertias appear much lower than values expected for compact ices, probably resulting from high surface porosity and poor surface consolidation. Comparison between Charon's thermal inertia and even lower values estimated for two other H 2O-covered Kuiper-Belt objects suggests that a vertical gradient of conductivity exists in the upper surface of these bodies. Finally, the observations indicate that the spectral emissivity of methane ice is close to unity at 24 m and decreases with increasing wavelength to 0.6 at 100 m. Future observations of thermal lightcurves over 70-500 m by Herschel should be very valuable to further constrain the emissivity behavior of the Pluto terrains.
  60. Barnes, S., 2011, IAUS, 273, 465, A nonlinear model for rotating cool stars
    A simple nonlinear model is introduced here to describe the rotational evolution of main sequence cool (FGKM) stars. It is formulated only in terms of the ratio of a star's rotation period, P, to its convective turnover timescale, , and two dimensionless constants which are specified using solar- and open cluster data. The model explains the origin of the two sequences, C/fast and I/slow, of rotating stars observed in open cluster color-period diagrams, and describes their evolution from C-type to I-type through the rotational gap, g, separating them. It explains why intermediate-mass open cluster stars have the longest periods, while higher- and lower-mass cool stars have shorter periods. It provides an exact expression for the age of a rotating cool star in terms of P and , thereby generalizing gyrochronology. The possible range of initial periods is shown to contribute upto 128 Myr to the gyro age errors of solar mass field stars. A transformation to color-period space shows how this model explains some detailed features in the color-period diagrams of open clusters, including the shapes and widths of the sequences, and the observed number density of stars across these diagrams.
  61. Saar, S., Dyke, M., Meibom, S., et al., (including Barnes, S.), 2011, IAUS, 273, 469, The dependence of maximum starspot amplitude and the amplitude distribution on stellar properties
    We combine photometric data from field stars, plus over a dozen open clusters and associations, to explore how the maximum photometric amplitude (Amax) and the distribution of amplitudes varies with stellar properties. We find a complex variation of Amax with inverse Rossby number Ro-1, which nevertheless can be modeled well with a simple model including an increase in Amax with rotation for low Ro-1, and a maximum level. Amax may then be further affected by differential rotation and a decline at the highest Ro-1. The distribution of Aspot below Amax varies with Ro-1 : it peaks at low Aspot with a long tail towards Amax for low Ro-1, but is more uniformly distributed at higher Ro-1. We investigate further dependences of the Aspot distributions on stellar properties, and speculate on the source of these variations.
  62. Mahmud, N., Crockett, C., Johns-Krull, C., et al., (including Prato, L.), 2011, ApJ, 736, 123, Starspot-induced Optical and Infrared Radial Velocity Variability in T Tauri Star Hubble I 4
    We report optical (~6150 A) and K-band (2.3 m) radial velocities obtained over two years for the pre-main-sequence weak-lined T Tauri star Hubble I 4. We detect periodic and near-sinusoidal radial velocity variations at both wavelengths, with a semi-amplitude of 1395 94 m s-1 in the optical and 365 80 m s-1 in the infrared. The lower velocity amplitude at the longer wavelength, combined with bisector analysis and spot modeling, indicates that there are large, cool spots on the stellar surface that are causing the radial velocity modulation. The radial velocities maintain phase coherence over hundreds of days suggesting that the starspots are long-lived. This is one of the first active stars where the spot-induced velocity modulation has been resolved in the infrared.
  63. Crossfield, I., Barman, T., Hansen, B., 2011, ApJ, 736, 132, High-resolution, Differential, Near-infrared Transmission Spectroscopy of GJ 1214b
    The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to characterize the planet's atmosphere. By cross-correlating the spectral changes through transit with a suite of theoretical atmosphere models, we search for variations associated with absorption in the planet atmosphere. Our observations are sufficient to rule out tested model atmospheres with wavelength-dependent transit depth variations >~ 5 10-4 over the wavelength range 2.1-2.4 m. Our sensitivity is limited by variable slit loss and telluric transmission effects. We find no positive signatures but successfully rule out a number of plausible atmospheric models, including the default assumption of a gaseous, H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made consistent if the absorption due to methane is reduced. Clouds can also render such an atmosphere consistent with our observations, but only if they lie higher in the atmosphere than indicated by recent optical and infrared measurements. When taken in concert with other observational constraints, our results support a model in which the atmosphere of GJ 1214b contains significant H and He, but where CH4 is depleted. If this depletion is the result of photochemical processes, it may also produce a haze that suppresses spectral features in the optical.
  64. Vercellone, S., Striani, E., Vittorini, V., et al., (including Taylor, B.), 2011, ApJL, 736, L38, The Brightest Gamma-Ray Flaring Blazar in the Sky: AGILE and Multi-wavelength Observations of 3C 454.3 During 2010 November
    Since 2005, the blazar 3C 454.3 has shown remarkable flaring activity at all frequencies, and during the last four years it has exhibited more than one -ray flare per year, becoming the most active -ray blazar in the sky. We present for the first time the multi-wavelength AGILE, Swift, INTEGRAL, and GASP-WEBT data collected in order to explain the extraordinary -ray flare of 3C 454.3 which occurred in 2010 November. On 2010 November 20 (MJD 55520), 3C 454.3 reached a peak flux (E >100 MeV) of Fp = (6.8 1.0) 10-5 photons cm-2 s-1 on a timescale of about 12 hr, more than a factor of six higher than the flux of the brightest steady -ray source, the Vela pulsar, and more than a factor of three brighter than its previous super-flare on 2009 December 2-3. The multi-wavelength data make possible a thorough study of the present event: the comparison with the previous outbursts indicates a close similarity to the one that occurred in 2009. By comparing the broadband emission before, during, and after the -ray flare, we find that the radio, optical, and X-ray emission varies within a factor of 2-3, whereas the -ray flux by a factor of 10. This remarkable behavior is modeled by an external Compton component driven by a substantial local enhancement of soft seed photons.
  65. Barnes, J., Jones, H., Barman, T., et al., (including Prato, L.), 2011, EPJWC, 16, 04001, Spectroscopic detection and characterisation of planetary atmospheres
    Space based broadband infrared observations of close orbiting extrasolar giant planets at transit and secondary eclipse have proved a successful means of determining atmospheric spectral energy distributions and molecular composition. Here, a ground-based spectroscopic technique to detect and characterise planetary atmospheres is presented. Since the planet need not be transiting, this method enables a greater sample of systems to be studied. By modelling the planetary signature as a function of phase, high resolution spectroscopy has the potential to recover the signature of molecules in planetary atmospheres.
  66. Jackson, M., Hunter, D., Lockman, F., 2011, EAS, 48, 167, Merging or Interacting? Determining the Nature of the Large-Scale Structure Around NGC 1569
    We present a preliminary large-scale, neutral Hydrogen emission map of structure around dwarf irregular (dIm) galaxy NGC 1569. These data were taken earlier this year with the Robert C. Byrd Green Bank Telescope (GBT). Our primary objective was to search for HI structure potentially connecting NGC 1569 with IC 342 as an explanation for the starburst and peculiar kinematics prevalent in NGC 1569.
  67. Borucki, W., Koch, D., Basri, G., et al., (including Dunham, E.), 2011, ApJ, 736, 19, Characteristics of Planetary Candidates Observed by Kepler. II. Analysis of the First Four Months of Data
    On 2011 February 1 the Kepler mission released data for 156,453 stars observed from the beginning of the science observations on 2009 May 2 through September 16. There are 1235 planetary candidates with transit-like signatures detected in this period. These are associated with 997 host stars. Distributions of the characteristics of the planetary candidates are separated into five class sizes: 68 candidates of approximately Earth-size (R p < 1.25 R ), 288 super-Earth-size (1.25 R <= R p < 2 R ), 662 Neptune-size (2 R <= R p < 6 R ), 165 Jupiter-size (6 R <= R p < 15 R ), and 19 up to twice the size of Jupiter (15 R <= R p < 22 R ). In the temperature range appropriate for the habitable zone, 54 candidates are found with sizes ranging from Earth-size to larger than that of Jupiter. Six are less than twice the size of the Earth. Over 74% of the planetary candidates are smaller than Neptune. The observed number versus size distribution of planetary candidates increases to a peak at two to three times the Earth-size and then declines inversely proportional to the area of the candidate. Our current best estimates of the intrinsic frequencies of planetary candidates, after correcting for geometric and sensitivity biases, are 5% for Earth-size candidates, 8% for super-Earth-size candidates, 18% for Neptune-size candidates, 2% for Jupiter-size candidates, and 0.1% for very large candidates; a total of 0.34 candidates per star. Multi-candidate, transiting systems are frequent; 17% of the host stars have multi-candidate systems, and 34% of all the candidates are part of multi-candidate systems.
  68. Porter, S., Grundy, W., 2011, ApJL, 736, L14, Post-capture Evolution of Potentially Habitable Exomoons
    The satellites of extrasolar planets (exomoons) have been recently proposed as astrobiological targets. Since giant planets in the habitable zone are thought to have migrated there, it is possible that they may have captured a former terrestrial planet or planetesimal. We therefore attempt to model the dynamical evolution of a terrestrial planet captured into orbit around a giant planet in the habitable zone of a star. We find that approximately half of loose elliptical orbits result in stable circular orbits over timescales of less than a few million years. We also find that those orbits are mostly at low inclination, but have no prograde/retrograde preference. In addition, we calculate the transit timing and duration variations for the resulting systems, and find that potentially habitable Earth-mass exomoons should be detectable.
  69. Crockett, C., Mahmud, N., Prato, L., et al., 2011, ApJ, 735, 78, Precision Radial Velocities with CSHELL
    Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s-1 precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M JUP exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.
  70. Barman, T., Macintosh, B., Konopacky, Q., et al., 2011, ApJL, 735, L39, The Young Planet-mass Object 2M1207b: A Cool, Cloudy, and Methane-poor Atmosphere
    The properties of 2M1207b, a young (~8 Myr) planet-mass companion, have lacked a satisfactory explanation for some time. The combination of low luminosity, red near-IR colors, and L-type near-IR spectrum (previously consistent with T eff ~ 1600 K) implies an abnormally small radius. Early explanations for the apparent underluminosity of 2M1207b invoked an edge-on disk or the remnant of a recent protoplanetary collision. The discovery of a second planet-mass object (HR8799b) with similar luminosity and colors as 2M1207b indicates that a third explanation, one of a purely atmospheric nature, is more likely. By including clouds, non-equilibrium chemistry, and low gravity, an atmosphere with effective temperature consistent with evolution cooling-track predictions is revealed. Consequently, 2M1207b, and others like it, requires no new physics to explain nor do they belong to a new class of objects. Instead they most likely represent the natural extension of cloudy substellar atmospheres down to low T eff and log (g). If this atmosphere only explanation for 2M1207b is correct, then very young planet-mass objects with near-IR spectra similar to field T dwarfs may be rare.
  71. Agudo, I., Marscher, A., Jorstad, S., et al., (including Taylor, B.), 2011, ApJL, 735, L10, On the Location of the -Ray Outburst Emission in the BL Lacertae Object AO 0235+164 Through Observations Across the Electromagnetic Spectrum
    We present observations of a major outburst at centimeter, millimeter, optical, X-ray, and -ray wavelengths of the BL Lacertae object AO 0235+164. We analyze the timing of multi-waveband variations in the flux and linear polarization, as well as changes in Very Long Baseline Array images at = 7 mm with ~0.15 milliarcsec resolution. The association of the events at different wavebands is confirmed at high statistical significance by probability arguments and Monte Carlo simulations. A series of sharp peaks in optical linear polarization, as well as a pronounced maximum in the 7 mm polarization of a superluminal jet knot, indicate rapid fluctuations in the degree of ordering of the magnetic field. These results lead us to conclude that the outburst occurred in the jet both in the quasi-stationary "core" and in the superluminal knot, both parsecs downstream of the supermassive black hole. We interpret the outburst as a consequence of the propagation of a disturbance, elongated along the line of sight by light-travel time delays, that passes through a standing recollimation shock in the core and propagates down the jet to create the superluminal knot. The multi-wavelength light curves vary together on long timescales (months/years), but the correspondence is poorer on shorter timescales. This, as well as the variability of the polarization and the dual location of the outburst, agrees with the expectations of a multi-zone emission model in which turbulence plays a major role in modulating the synchrotron and inverse Compton fluxes.
  72. Buie, M., Trilling, D., Wasserman, L., et al., 2011, ApJS, 194, 40, A Large and Faint Photometric Catalog on the Ecliptic
    A photometric catalog, developed for the calibration of the Deep Ecliptic Survey, is presented. The catalog contains 213,272 unique sources that were measured in V and R filters and transformed to the Johnson-Cousins systems using the Landolt standard catalog. All of the sources lie within 6 of the ecliptic and cover all longitudes except for the densest stellar regions nearest the galactic center. Seventeen percent of the sources in the catalog are derived from three or more nights of observation. The catalog contains sources as faint as R ~19 but the largest fraction fall in the R ~15-16 (V ~16-17) mag range. All magnitude bins down to R = 19 have a significant fraction of objects with uncertainties <=0.1 mag.
  73. Meech, K., A'Hearn, M., Adams, J., et al., (including Knight, M., Schleicher, D., Schwieterman, E., Wasserman, L.), 2011, ApJL, 734, L1, EPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
    Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was ~16.4 hr. Starting in 2010 August the period changed from 16.6 hr to near 19 hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO2-driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production.
  74. Grundy, W., Noll, K., Nimmo, F., et al., (including Roe, H., Porter, S.), 2011, Icar, 213, 678, Five new and three improved mutual orbits of transneptunian binaries
    We present three improved and five new mutual orbits of transneptunian binary systems (58534) Logos-Zoe, (66652) Borasisi-Pabu, (88611) Teharonhiawako-Sawiskera, (123509) 2000 WK 183, (149780) Altjira, 2001 QY 297, 2003 QW 111, and 2003 QY 90 based on Hubble Space Telescope and Keck II laser guide star adaptive optics observations. Combining the five new orbit solutions with 17 previously known orbits yields a sample of 22 mutual orbits for which the period P, semimajor axis a, and eccentricity e have been determined. These orbits have mutual periods ranging from 5 to over 800 days, semimajor axes ranging from 1600 to 37,000 km, eccentricities ranging from 0 to 0.8, and system masses ranging from 2 10 17 to 2 10 22 kg. Based on the relative brightnesses of primaries and secondaries, most of these systems consist of near equal-sized pairs, although a few of the most massive systems are more lopsided. The observed distribution of orbital properties suggests that the most loosely-bound transneptunian binary systems are only found on dynamically cold heliocentric orbits. Of the 22 known binary mutual orbits, orientation ambiguities are now resolved for 9, of which 7 are prograde and 2 are retrograde, consistent with a random distribution of orbital orientations, but not with models predicting a strong preference for retrograde orbits. To the extent that other perturbations are not dominant, the binary systems undergo Kozai oscillations of their eccentricities and inclinations with periods of the order of tens of thousands to millions of years, some with strikingly high amplitudes.
  75. Benecchi, S., Noll, K., Stephens, D., et al., (including Grundy, W.), 2011, Icar, 213, 693, Optical and infrared colors of transneptunian objects observed with HST
    We present optical colors of 72 transneptunian objects (TNOs), and infrared colors of 80 TNOs obtained with the WFPC2 and NICMOS instruments, respectively, on the Hubble Space Telescope (HST). Both optical and infrared colors are available for 32 objects that overlap between the datasets. This dataset adds an especially uniform, consistent and large contribution to the overall sample of colors, particularly in the infrared. The range of our measured colors is consistent with other colors reported in the literature at both optical and infrared wavelengths. We find generally good agreement for objects measured by both us and others; 88.1% have better than 2 sigma agreement. The median absolute magnitude, H V, magnitude of our optical sample is 7.2, modestly smaller (0.5 mag) than for previous samples. The median H V in our infrared sample is 6.7. We find no new correlations between color and dynamical properties (semi-major axis, eccentricity, inclination and perihelion). We do find that colors of Classical objects with i < 6 come from a different distribution than either the Resonant or excited populations in the visible at the >99.99% level with a K-S test. The same conclusion is found in the infrared at a slightly lower significance level, 99.72%. Two Haumea collision fragments with strong near infrared ice bands are easily identified with broad HST infrared filters and point to an efficient search strategy for identifying more such objects. We find evidence for variability in (19255) 1999 VK 8, 1999 OE 4, 2000 CE 105, 1998 KG 62 and 1998 WX 31.
  76. Chatterjee, R., Marscher, A., Jorstad, S., et al., (including Taylor, B.), 2011, ApJ, 734, 43, Connection Between the Accretion Disk and Jet in the Radio Galaxy 3C 111
    We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4-10 keV), optical (R band), and radio (14.5, 37, and 230 GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the six years of observation, significant dips in the X-ray light curve are followed by ejections of bright superluminal knots in the VLBA images. This shows a clear connection between the radiative state near the black hole, where the X-rays are produced, and events in the jet. The X-ray continuum flux and Fe line intensity are strongly correlated, with a time lag shorter than 90 days and consistent with zero. This implies that the Fe line is generated within 90 lt-day of the source of the X-ray continuum. The power spectral density function of X-ray variations contains a break, with a steeper slope at shorter timescales. The break timescale of 13+12 - 6 days is commensurate with scaling according to the mass of the central black hole based on observations of Seyfert galaxies and black hole X-ray binaries (BHXRBs). The data are consistent with the standard paradigm, in which the X-rays are predominantly produced by inverse Compton scattering of thermal optical/UV seed photons from the accretion disk by a distribution of hot electronsthe coronasituated near the disk. Most of the optical emission is generated in the accretion disk due to reprocessing of the X-ray emission. The relationships that we have uncovered between the accretion disk and the jet in 3C 111, as well as in the Fanaroff-Riley class I radio galaxy 3C 120 in a previous paper, support the paradigm that active galactic nuclei and Galactic BHXRBs are fundamentally similar, with characteristic time and size scales proportional to the mass of the central black hole.
  77. Neugent, K., Massey, P., 2011, ApJ, 733, 123, The Wolf-Rayet Content of M33
    Wolf-Rayet (WR) stars are evolved massive stars, and the relative number of WC-type and WN-type WRs should vary with metallicity, providing a sensitive test of stellar evolutionary theory. The observed WC/WN ratio is much higher than that predicted by theory in some galaxies but this could be due to observational incompleteness for WN types, which have weaker lines. Previous studies of M33's WR content show a galactocentric gradient in the relative numbers of WCs and WNs, but only small regions have been surveyed with sufficient sensitivity to detect all of the WNs. Here, we present a sensitive survey for WRs covering all of M33, finding 55 new WRs, mostly of WN type. Our spectroscopy also improves the spectral types of many previously known WRs, establishing in one case that the star is actually a background quasar. The total number of spectroscopically confirmed WRs in M33 is 206, a number we argue is complete to ~5%, with most WRs residing in OB associations, although ~2% are truly isolated. The WC/WN ratio in the central regions (<2 kpc) of M33 is much higher than that predicted by the current Geneva evolutionary models, while the WC/WN ratios in the outer regions are in good accord, as are the values in the Small Magellanic Cloud and Large Magellanic Cloud. The WC/WN ratio and the WC subtype distribution both argue that the oxygen abundance gradient in M33 is significantly larger than that found by some recent studies, but are consistent with the two-component model proposed by Magrini et al.

    Observations reported here were partially obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. MMT telescope time was granted by NOAO, through the Telescope System Instrumentation Program (TSIP). TSIP is funded by the National Science Foundation.

  78. Knight, M., Schleicher, D., 2011, AJ, 141, 183, CN Morphology Studies of Comet 103P/Hartley 2
    We report on narrowband CN imaging of Comet 103P/Hartley 2 obtained at Lowell Observatory on 39 nights from 2010 July until 2011 January. We observed two features, one generally to the north and the other generally to the south. The CN morphology varied during the apparition: no morphology was seen in July; in August and September, the northern feature dominated and appeared as a mostly face-on spiral; in October, November, and December, the northern and southern features were roughly equal in brightness and looked like more side-on corkscrews; in January, the southern feature was dominant but the morphology was indistinct due to very low signal. The morphology changed smoothly during each night and similar morphology was seen from night to night. However, the morphology did not exactly repeat each rotation cycle, suggesting that there is a small non-principal axis rotation. Based on the repetition of the morphology, we find evidence that the fundamental rotation period was increasing: 16.7 hr from August 13 to 17, 17.2 hr from September 10 to 13, 18.2 hr from October 12 to 19, and 18.7 hr from October 31 to November 7. We conducted Monte Carlo jet modeling to constrain the pole orientation and locations of the active regions based on the observed morphology. Our preliminary, self-consistent pole solution has an obliquity of 10 relative to the comet's orbital plane (i.e., it is centered near R.A. = 257 and decl. = +67 with an uncertainty around this position of about 15) and has two mid-latitude sources, one in each hemisphere.
  79. Schleicher, D., Bair, A., 2011, AJ, 141, 177, The Composition of the Interior of Comet 73P/Schwassmann-Wachmann 3: Results from Narrowband Photometry of Multiple Components
    We present analyses of and results for multiple components of Comet 73P/Schwassmann-Wachmann 3 at two apparitions. A total of eight nights of narrowband photometry were obtained during the comet's 2006 apparition from February 25 to September 24 at Lowell Observatory. The comet's very close passage of Earth and sporadic outbursts allowed us to successfully measure the primary body, "C," as well as components "B," "G," and "R." We additionally include four nights of narrowband photometry from 1995, obtained at Perth Observatory between October 19 and November 21, one to two months after the initial fragmentation event and outburst. We determined production rates for OH, NH, CN, C3, and C2, along with a proxy for the dust production, A()f, and our 2006 measurements show considerable variation in behavior among the components, and for the gas species as compared to the dust grains. The two components having the best temporal coverage, C and B, both exhibit evidence for strong seasonal effects with larger production rates prior to perihelion than after. Because C showed little or no evidence of outbursts, its derived active area (based on water production rates) appears to be dominated by ice vaporizing from the nucleus; the fractional active area of the total nucleus surface varied from 56% (2006 February) to 125% (May) and back down to 11% (September) following perihelion. Except for when Component B was in outburst, C always had higher production rates than B, implying a significantly larger effective active area on its nucleus' surface. Unlike the gas species, dust production showed large and varying trends with both aperture size and with time, implying a significant change in the properties of the dust grains during the 2006 apparition. Due to the fragmentation event in 1995, the majority of active surfaces on the various components observed in 2006 are freshly exposed from the interior of Schwassmann-Wachmann 3's nucleus, thus permitting us to directly probe the chemical composition of the relatively pristine interior. Relative abundances, expressed as production rate ratios between gas species, were compared among the four components and to values determined prior to the fragmentation, as well as to those measured in other comets. Our measurements indicate each component, to within the uncertainties, has the same composition and that this composition is consistent with that measured in the pre-fragmented nucleus. Moreover, C2 and C3 are both strongly depleted when compared to the majority of comets, placing Schwassmann-Wachmann 3 among the more extreme comets within the carbon-chain depleted class identified by A'Hearn et al. With the material released from the interior of the comet yielding comparable depletions of carbon-chain molecules as the original surface of the nucleus, we conclude that carbon-chain depletion is not caused by evolution of the surface, and so must instead reflect the primordial composition at the time and location that the comet accreted.
  80. Horch, E., van Altena, W., Howell, S., et al., 2011, AJ, 141, 180, Observations of Binary Stars with the Differential Speckle Survey Instrument. III. Measures below the Diffraction Limit of the WIYN Telescope
    In this paper, we study the ability of CCD- and electron-multiplying-CCD-based speckle imaging to obtain reliable astrometry and photometry of binary stars below the diffraction limit of the WIYN 3.5 m Telescope. We present a total of 120 measures of binary stars, 75 of which are below the diffraction limit. The measures are divided into two groups that have different measurement accuracy and precision. The first group is composed of standard speckle observations, that is, a sequence of speckle images taken in a single filter, while the second group consists of paired observations where the two observations are taken on the same observing run and in different filters. The more recent paired observations were taken simultaneously with the Differential Speckle Survey Instrument, which is a two-channel speckle imaging system. In comparing our results to the ephemeris positions of binaries with known orbits, we find that paired observations provide the opportunity to identify cases of systematic error in separation below the diffraction limit and after removing these from consideration, we obtain a linear measurement uncertainty of 3-4 mas. However, if observations are unpaired or if two observations taken in the same filter are paired, it becomes harder to identify cases of systematic error, presumably because the largest source of this error is residual atmospheric dispersion, which is color dependent. When observations are unpaired, we find that it is unwise to report separations below approximately 20 mas, as these are most susceptible to this effect. Using the final results obtained, we are able to update two older orbits in the literature and present preliminary orbits for three systems that were discovered by Hipparcos.

    The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories.

  81. Muinonen, K., Oszkiewicz, D., Pieniluoma, T., et al., 2011, sssb, 7, Asteroid orbital inversion using Markov-chain Monte Carlo methods
    No abstract found.
  82. Oszkiewicz, D., Bowell, T., Muinonen, K., et al., (including Wasserman, L.), 2011, sssb, 23, Asteroid physical and dynamical properties from Lowell Observatory photometric database
    No abstract found.
  83. Massey, P., Drout, M., Tokarz, S., et al., 2011, AAS, 218, 125.06, The Red and Yellow Supergiants in M33: Kinematics and Massive Star Evolution
    Massive star evolution is hard to model, owing to the complications of mass-loss, uncertainties over mixing and convection, the effects of rotation, and so on. It is generally agreed that the most massive stars spend their He-burning lives as Wolf-Rayet stars. Stars of slightly smaller masses spend most of their He-burning phase as red supergiants, after briefly passing through a yellow supergiant phase. We are interested in identifying the numbers and physical properties of these stars throughout the star-forming galaxies of the Local Group in an effort to test stellar evolutionary models at varying metallicities. However, foreground contamination by Milky Way dwarfs is severe for both the yellow supergiants (YSGs) and red supergiants (RSGs). Using the photometry of the Local Group Galaxy Survey, we have used two-color information (B-V vs V-R) to separate likely foreground dwarfs from bona fide RSGs in M33, and obtained radial velocities with Hectospec on the 6.5-m MMT. The radial velocities refine the rotation curves of previous studies, and demonstrate that the rotation curve is quite flat. With the new velocity data we then separate the yellow supergiant population from the foreground using radial velocities as well. Since the number of Wolf-Rayet stars is now known to a few percent in M33 (Neugent et al. 2011, ApJ, in press, as well as poster at this meeting) it is now possible to compare the numbers of RSGs, YSGs, and WRs in this nearby spiral. This work is supported by the National Science Foundation through AST-1008020.
  84. Neugent, K., Massey, P., 2011, AAS, 218, 125.07, Wolf-Rayet Stars in the Local Group
    The physics behind hot, massive stars is complicated, making the stars' properties 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. Here we discuss our candidate selection process, as well as the results from our most recent study of M33 which yielded 56 new WR stars. The relative number of WCs to WNs would support there being a strong metallicity gradient. This work was supported by the National Science Foundation under AST-1008020.
  85. Henden, A., Levine, S., Terrell, D., et al., 2011, AAS, 218, 126.01, Data Release 3 of the AAVSO All-Sky Photometric Survey (APASS)
    APASS is an all-sky survey in 5 filters (B,V,g',r',i') covering the magnitude range 10<V<17. It is currently underway at two sites: Dark Ridge Observatory in New Mexico, and CTIO in Chile. The survey will take approximately two years to complete, and will provide a precision of 0.02mag for well-sampled stars. This paper presents the current status of the project and provides the access methods to the catalog.
  86. Morales-Calderon, M., Stauffer, J., Prato, L., et al., 2011, AAS, 218, 130.08, New Data for Five New Orion PMS Eclipsing Binaries from the Spitzer YSOVAR Program.
    In Fall 2009, we conducted a large, multi-wavelength time-series photometric monitoring campaign of about a one square degree region of the Orion Nebula cluster (ONC). From these data we identify nine stars in our field of view whose light curves show eclipse features. Four of these are the previously known ONC eclipsing binaries (EBs) and the other five systems are newly identified ONC PMS EB candidates - more than doubling what was known up to now. Here we present our follow-up observations and current work to confirm these candidates.
  87. Meibom, S., Saar, S., Barnes, S., 2011, AAS, 218, 133.03, Chandra Observations of the Well-Studied 180 Myr Old Open Cluster M35
    M35 is a relatively close ( 800 pc), rich, young ( 180 Myr) open cluster which has been the focus of extensive multi-epoch spectroscopic and photometric study. Some 250 single and 100 binary stars ( 50 with orbits) are confirmed members and 310 have measured rotation periods. This detailed information about membership, binarity, and rotation, makes M35 an ideal target for studying not only the rotation-activity-age relation for cool stars, but also for the effect of a stellar companion on this relationship. We present preliminary results of a 130 ksec ACIS-I observation near the core of the M35, containing 180 cluster members. We explore how the coronal flux and temperature change across the cluster's color-period diagram, how binarity affects these results, and compare our findings with other clusters.

    This work was funded by Chandra Award No. GO0-11041A.

  88. Borucki, W., Koch, D., Batalha, N., et al., (including Dunham, E.), 2011, AAS, 218, 218.01, First Estimate of the Exoplanet Population from Kepler Observations
    William J. Borucki, David G. Koch, Natalie Batalha, Derek Buzasi , Doug Caldwell, David Charbonneau, Jessie L. Christiansen, David R. Ciardi, Edward Dunham, Eric B. Ford, Steve Thomas N. Gautier III, Steve Howell, Jon M. Jenkins, Jeffery Kolodziejczak, Geoffrey W. Marcy, Jason Rowe, and Andrej Prsa

    A model was developed to provide a first estimate of the intrinsic frequency of planetary candidates based on the number of detected planetary candidates and the measured noise for each of the 156,000 observed stars. The estimated distributions for the exoplanet frequency are presented with respect to the semi-major axis and the stellar effective temperature and represent values appropriate only to short-period candidates. Improved estimates are expected after a Monte Carlo study of the sensitivity of the data analysis pipeline to transit signals injected at the pixel level is completed.

  89. Jensen, A., Redfield, S., Cochran, W., et al., (including Barman, T.), 2011, AAS, 218, 218.06, A Search for H-alpha Absorption in Exoplanetary Exospheres
    The number of exoplanets with detected atmospheres is rapidly increasing. Particularly intriguing are detections of hydrogen that are attributed to the upper, unbound portion of their atmospheres (i.e. the "exospheres") and indicate that some gas giants may be evaporating. Exospheric hydrogen has only been detected in Lyman-alpha, which, as with all single line detections, only provides limited information about physical conditions such as density and temperature. A much better understanding of exospheres and their evolution would be gained through a constraint on H-alpha. We have obtained more than 100 total hours of spectroscopic observations with the Hobby-Eberly Telescope of five different exoplanetary targets, with the goal of deriving transmission spectra of exoplanetary atmospheres; two of these targets have had their exospheres detected in Lyman-alpha. Here we report on our search for H-alpha absorption in these exospheres, and the implications for their physical conditions and evolution. This work is supported by the National Science Foundation through an Astronomy and Astrophysics Research Grant (AST-0903573). The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen and is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.
  90. Person, M., Elliot, J., Bosh, A., et al., 2011, AAS, 218, 224.12, Constraints On The Size Of KBO (50000) Quaoar From A Single-chord Stellar Occultation
    Observations of the stellar occultation of the magnitude 16.2 star 26029635 UCAC2 (2MASS ID 1275509401) by (50000) Quaoar were made at MIT's George R. Wallace, Jr., Astrophysical Observatory on the night of 11 February 2011 UT (Sallum, this meeting). A single occultation chord dataset was obtained and will be analyzed to place a lower limit on the size of Quaoar based on this chord. The resulting value will be compared to Quaoar size estimates from other techniques including direct imaging with the Hubble Space Telescope (Brown 2004), and Spitzer Infrared imaging (Stansberry 2007), which give significantly differing results given their error bars (1260 190 km and 844.4 +206.7/-189.6 km, respectively).

    The difficulties of analyzing low-cadence and single-chord occultation data will be examined, and comparisons to other such occultation chords of this type (e.g. Elliot 2010) will be made.

    This work is supported in part by grant NNX10AB27G to MIT from NASA's Planetary Astronomy Division. Student participation is supported in part by NSF's REU program, MIT's Undergraduate Research Opportunities Program, NASA's Massachusetts Space Grant, and the George R. Wallace, Jr., Astrophysical Observatory.

  91. Sallum, S., Brothers, T., Elliot, J., et al., 2011, AAS, 218, 224.13, First Observations of a Stellar Occultation by KBO (50000) Quaoar from MIT's George R. Wallace, Jr., Astrophysical Observatory
    Here we report the first recorded observations of a stellar occultation by Kuiper Belt Object (KBO) (50000) Quaoar. We detected a single-chord stellar occultation by Quaoar of a magnitude 16.2 star designated 26029635 UCAC2 (2MASS ID 1275509401), which occurred on 11 February 2011 UT.

    The prediction of the occultation was made using long baseline astrometric observations of Quaoar from several sites as part of the MIT Planetary Astronomy Laboratory's continuing effort to improve KBO positions for occultation prediction. The successful observations were made with a Celestron C14 0.36 m telescope and an SBIG STL-1001E CCD camera on a Paramount ME robotic mount. These observations show that a relatively accessible level of astronomical equipment, of the class often used by amateur astronomers, can be used to record KBO occultations. The data were taken at MIT's George R. Wallace, Jr., Astrophysical Observatory in Westford, MA. A light curve was generated from the data using aperture photometry on the individual images and is presented here. This light curve is being analyzed by Person et al. (this meeting) to provide constraints on Quaoar's size. We also discuss various observing strategies that could be used in the future to optimize the data from this type of event.

    This work was supported in part by grant NNX10AB27G to MIT from NASA's Planetary Astronomy Division. Student participation was supported in part by NSF's REU program, MIT's Undergraduate Research Opportunities Program, NASA's Massachusetts Space Grant, and the George R. Wallace, Jr., Astrophysical Observatory.

  92. Janes, K., Barnes, S., Meibom, S., et al., 2011, AAS, 218, 227.06, NGC 6811: An Intermediate-age Cluster In The Kepler Field
    NGC 6811 is one of four open clusters located in the Kepler spacecraft field of view. We have observed the cluster on several occasions with the 1.08-meter Hall and 1.83-meter Perkins telescopes at Lowell Observatory. A well-defined main sequence and red giant "clump" are clearly visible in the color-magnitude diagram; several of the red clump stars have velocities consistent with cluster membership. We have analyzed the data from two photometric nights (one night with each telescope) and we derive the following parameters for the cluster: E(B-V) = 0.04 0.04, (m-M)o = 11.0 0.2 and log(age) = 9.05 0.10, all assuming a slightly metal-poor composition. We are continuing our analysis with additional photometry.
  93. Pompea, S., Sparks, R., Dugan, C., et al., (including Schindler, K.), 2011, AAS, 218, 333.07, The Flagstaff Star Party Model for Using Galileoscopes: Evaluation Report
    The Galileoscope is a low-cost, high optical quality telescope kit designed for education and outreach during the International Year of Astronomy 2009. The Galileoscope has been used in a variety of formal and informal education settings around the world.

    We have been developing a model for large star parties by collaborating with school districts and Science Foundation Arizona. We held our first large start party last fall in Flagstaff and have our next one scheduled for April of 2011 in Yuma, Arizona.

    The model we are using includes and extensive professional development component for teacher. Each teacher attends a day-long professional development workshop that covers the optics of a telescope, how to assemble a Gaileoscope and how to make astronomical observations. Each teacher receives an optics eduction kit including all the materials necessary to do the activities in their classrooms. The teachers receive Galileoscopes and tripods for their classrooms as well.

    Before the star party, NOAO staff visit the classrooms to assist students and teachers with the Galileoscope and to teach observing techniques to ensure all the Galileoscopes are working and can be used at the star party.

    The evening of the star party students gather at the site (usually a local park or school grounds) for an evening of observing. Each student tries to find a variety of different objects to get their passports stamped. At the end of the evening, a drawing is held for students who have observed the designated objects.

    We will detail the process of planning and holding the star party including professional development, logistics and follow up with the students.

  94. Latham, D., Rowe, J., Quinn, S., et al., (including Dunham, E.), 2011, ApJL, 732, L24, A First Comparison of Kepler Planet Candidates in Single and Multiple Systems
    In this Letter, we present an overview of the rich population of systems with multiple candidate transiting planets found in the first four months of Kepler data. The census of multiples includes 115 targets that show two candidate planets, 45 with three, eight with four, and one each with five and six, for a total of 170 systems with 408 candidates. When compared to the 827 systems with only one candidate, the multiples account for 17% of the total number of systems, and one-third of all the planet candidates. We compare the characteristics of candidates found in multiples with those found in singles. False positives due to eclipsing binaries are much less common for the multiples, as expected. Singles and multiples are both dominated by planets smaller than Neptune; 69+2 - 3% for singles and 86+2 - 5% for multiples. This result, that systems with multiple transiting planets are less likely to include a transiting giant planet, suggests that close-in giant planets tend to disrupt the orbital inclinations of small planets in flat systems, or maybe even prevent the formation of such systems in the first place.
  95. Morales-Calderon, M., Stauffer, J., Hillenbrand, L., et al., (including Wasserman, L.), 2011, ApJ, 733, 50, Ysovar: The First Sensitive, Wide-area, Mid-infrared Photometric Monitoring of the Orion Nebula Cluster
    We present initial results from time-series imaging at infrared wavelengths of 0.9 deg2 in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5 m data over 40 consecutive days. We extracted light curves with ~3% photometric accuracy for ~2000 ONC members ranging from several solar masses down to well below the hydrogen-burning mass limit. For many of the stars, we also have time-series photometry obtained at optical (Ic ) and/or near-infrared (JK s ) wavelengths. Our data set can be mined to determine stellar rotation periods, identify new pre-main-sequence eclipsing binaries, search for new substellar Orion members, and help better determine the frequency of circumstellar disks as a function of stellar mass in the ONC. Our primary focus is the unique ability of 3.6 and 4.5 m variability information to improve our understanding of inner disk processes and structure in the Class I and II young stellar objects (YSOs). In this paper, we provide a brief overview of the YSOVAR Orion data obtained in Fall 2009 and highlight our light curves for AA-Tau analogsYSOs with narrow dips in flux, most probably due to disk density structures passing through our line of sight. Detailed follow-up observations are needed in order to better quantify the nature of the obscuring bodies and what this implies for the structure of the inner disks of YSOs.
  96. Barman, T., Macintosh, B., Konopacky, Q., et al., 2011, ApJ, 733, 65, Clouds and Chemistry in the Atmosphere of Extrasolar Planet HR8799b
    Using the integral field spectrograph OSIRIS, on the Keck II telescope, broad near-infrared H- and K-band spectra of the young exoplanet HR8799b have been obtained. In addition, six new narrowband photometric measurements have been taken across the H and K bands. These data are combined with previously published photometry for an analysis of the planet's atmospheric properties. Thick photospheric dust cloud opacity is invoked to explain the planet's red near-IR colors and relatively smooth near-IR spectrum. Strong water absorption is detected, indicating a hydrogen-rich atmosphere. Only weak CH4 absorption is detected at K band, indicating efficient vertical mixing and a disequilibrium CO/CH4 ratio at photospheric depths. The H-band spectrum has a distinct triangular shape consistent with low surface gravity. New giant planet atmosphere models are compared to these data with best-fitting bulk parameters, T eff = 1100 K 100 and log (g) = 3.5 0.5 (for solar composition). Given the observed luminosity (log L obs/L sun ~ - 5.1), these values correspond to a radius of 0.75 R Jup +0.17 - 0.12 and a mass of ~0.72 M Jup +2.6 - 0.6strikingly inconsistent with interior/evolution models. Enhanced metallicity (up to ~10 that of the Sun) along with thick clouds and non-equilibrium chemistry are likely required to reproduce the complete ensemble of spectroscopic and photometric data and the low effective temperatures (<1000 K) required by the evolution models.
  97. Meibom, S., Barnes, S., Latham, D., et al., 2011, ApJL, 733, L9, The Kepler Cluster Study: Stellar Rotation in NGC 6811
    We present rotation periods for 71 single dwarf members of the open cluster NGC 6811 determined using photometry from NASA's Kepler mission. The results are the first from The Kepler Cluster Study, which combines Kepler's photometry with ground-based spectroscopy for cluster membership and binarity. The rotation periods delineate a tight sequence in the NGC 6811 color-period diagram from ~1 day at mid-F to ~11 days at early-K spectral type. This result extends to 1 Gyr similar prior results in the ~600 Myr Hyades and Praesepe clusters, suggesting that rotation periods for cool dwarf stars delineate a well-defined surface in the three-dimensional space of color (mass), rotation, and age. It implies that reliable ages can be derived for field dwarf stars with measured colors and rotation periods, and it promises to enable further understanding of various aspects of stellar rotation and activity for cool stars.
  98. Platais, I., Girard, T., Vieira, K., et al., (including Barnes, S.), 2011, MNRAS, 413, 1024, A deep proper-motion survey of the nearby open cluster Blanco 1
    We provide two comprehensive catalogues of positions and proper motions in the area of open cluster Blanco 1. The main catalogue, CTLGM, contains 6271 objects down to V 18.5 and covers a circular 11 deg2 area. The accuracy of CTLGM proper motions, at about 0.3-0.5 mas yr-1 for well-measured stars, permits an excellent segregation between the cluster and field stars. The vector-point diagram of proper motions indicates an estimated total of 165 cluster members among the stars in our sample, while 314 stars with < 2.5 mas yr-1 have membership probabilities P 1 per cent. We also explored the astrometric potential of the Catalogue of Objects and Measured Parameters from All Sky Surveys (COMPASS) data base in order to obtain additional proper motions for fainter stars in the area of Blanco 1. This effort produced the second catalogue of proper motions, CTLGD, containing 11 598 objects down to V 21. A total of 4273 objects are common between the two catalogues. The accuracy of proper motions in CTLGD ranges from 1.0 to 6 mas yr-1. A combination of both proper-motion catalogues was instrumental in confirming that Blanco 1 contains a large population of M dwarfs (150 down to M5 V - the limit of our survey). In many respects, Blanco 1 is a scaled down twin of the Pleiades. The noted discrepancy between the distance from a new Hipparcos parallax of Blanco 1 and the cluster's photometric distance, at least partially, might be due to the apparent correlation between parallax and proper motion in right ascension for the ensemble of cluster members.
  99. Meech, K., Pittichova, J., Yang, B., et al., (including Herrmann, K., Taylor, B., Wasserman, L.), 2011, Icar, 213, 323, Deep Impact, Stardust-NExT and the behavior of Comet 9P/Tempel 1 from 1997 to 2010
    We present observational data for Comet 9P/Tempel 1 taken from 1997 through 2010 in an international collaboration in support of the Deep Impact and Stardust-NExT missions. The data were obtained to characterize the nucleus prior to the Deep Impact 2005 encounter, and to enable us to understand the rotation state in order to make a time of arrival adjustment in February 2010 that would allow us to image at least 25% of the nucleus seen by the Deep Impact spacecraft to better than 80 m/pixel, and to image the crater made during the encounter, if possible. In total, 500 whole or partial nights were allocated to this project at 14 observatories worldwide, utilizing 25 telescopes. Seventy percent of these nights yielded useful data. The data were used to determine the linear phase coefficient for the comet in the R-band to be 0.045 0.001 mag deg -1 from 1 to 16. Cometary activity was observed to begin inbound near r 4.0 AU and the activity ended near r 4.6 AU as seen from the heliocentric secular light curves, water-sublimation models and from dust dynamical modeling. The light curve exhibits a significant pre- and post-perihelion brightness and activity asymmetry. There was a secular decrease in activity between the 2000 and 2005 perihelion passages of 20%. The post-perihelion light curve cannot be easily explained by a simple decrease in solar insolation or observing geometry. CN emission was detected in the comet at 2.43 AU pre-perihelion, and by r = 2.24 AU emission from C 2 and C 3 were evident. In December 2004 the production rate of CN increased from 1.8 10 23 mol s -1 to QCN = 2.75 10 23 mol s -1 in early January 2005 and 9.3 10 24 mol s -1 on June 6, 2005 at r = 1.53 AU.
  100. Belton, M., Meech, K., Chesley, S., et al., (including Herrmann, K., Taylor, B., Wasserman, L.), 2011, Icar, 213, 345, Stardust-NExT, Deep Impact, and the accelerating spin of 9P/Tempel 1
    The evolution of the spin rate of Comet 9P/Tempel 1 through two perihelion passages (in 2000 and 2005) is determined from 1922 Earth-based observations taken over a period of 13 year as part of a World-Wide observing campaign and from 2888 observations taken over a period of 50 days from the Deep Impact spacecraft. We determine the following sidereal spin rates (periods): 209.023 0.025/dy (41.335 0.005 h) prior to the 2000 perihelion passage, 210.448 0.016/dy (41.055 0.003 h) for the interval between the 2000 and 2005 perihelion passages, 211.856 0.030/dy (40.783 0.006 h) from Deep Impact photometry just prior to the 2005 perihelion passage, and 211.625 0.012/dy (40.827 0.002 h) in the interval 2006-2010 following the 2005 perihelion passage. The period decreased by 16.8 0.3 min during the 2000 passage and by 13.7 0.2 min during the 2005 passage suggesting a secular decrease in the net torque. The change in spin rate is asymmetric with respect to perihelion with the maximum net torque being applied on approach to perihelion. The Deep Impact data alone show that the spin rate was increasing at a rate of 0.024 0.003/dy/dy at JD2453530.60510 (i.e., 25.134 dy before impact), which provides independent confirmation of the change seen in the Earth-based observations. The rotational phase of the nucleus at times before and after each perihelion and at the Deep Impact encounter is estimated based on the Thomas et al. (Thomas et al. [2007]. Icarus 187, 4-15) pole and longitude system. The possibility of a 180 error in the rotational phase is assessed and found to be significant. Analytical and physical modeling of the behavior of the spin rate through of each perihelion is presented and used as a basis to predict the rotational state of the nucleus at the time of the nominal (i.e., prior to February 2010) Stardust-NExT encounter on 2011 February 14 at 20:42. We find that a net torque in the range of 0.3-2.5 10 7 kg m 2 s -2 acts on the nucleus during perihelion passage. The spin rate initially slows down on approach to perihelion and then passes through a minimum. It then accelerates rapidly as it passes through perihelion eventually reaching a maximum post-perihelion. It then decreases to a stable value as the nucleus moves away from the Sun. We find that the pole direction is unlikely to precess by more than 1 per perihelion passage. The trend of the period with time and the fact that the modeled peak torque occurs before perihelion are in agreement with published accounts of trends in water production rate and suggests that widespread H 2O out-gassing from the surface is largely responsible for the observed spin-up.
  101. Witte, S., Helling, C., Barman, T., et al., 2011, A&A, 529, A44, Dust in brown dwarfs and extra-solar planets. III. Testing synthetic spectra on observations
    Context. This work is concerned with dust formation in ultra-cool atmospheres, encompassing the latest type stars, brown dwarfs, and hot giant exoplanets. Dust represents one of the most important and yet least understood sources of opacity in these types of objects.
    Aims: We compare our model spectra with SpeX data in order to draw conclusions about the dust cloud structure and related quantities in ultra-cool atmospheres.
    Methods: We use the self-consistent Drift-Phoenix atmosphere code, which features a kinetic dust formation mechanism and accounts for the dust cloud influence on the spectra.
    Results: We present fits of our latest model spectra to observations that cover a wide range of our model grid. The results are remarkably good, yielding significant improvement over the older Cond-/Dusty-Phoenix models, especially in the L-dwarf regime. The new models are able to properly reproduce observed spectra, including complicated features such as the molecular band strengths. This raises confidence in the reliability of our dust-modeling approach.
    Conclusions: We demonstrate that our code produces excellent results concerning the fitting with observations. This suggests that our dust cloud and atmosphere structures are reasonably accurate. Like all other current cloud models, ours is not able to produce satisfying results for spectral types later than L6 without manually tuning down the amount of dust. Our results show the formation of convective cells within the cloud, which are able to destroy the lower cloud parts. The dust opacity is reduced significantly without the need to tune the dust cloud thickness. There are indications that the cycle of dust accumulation and cloud destruction by convection is time-dependent on rather long timescales. Considering a statistical distribution of locally variable dust clouds over a dwarf's surface can result in a large number of spectral configurations for the same model atmosphere parameters, hence introducing an additional and more or less random degree of freedom to those atmospheres. Without resorting to the model atmosphere parameters, this alone can account for the unusually red and blue objects that have been discovered.
  102. Grundy, W., Morrison, S., Bovyn, M., et al., 2011, Icar, 212, 941, Remote sensing D/H ratios in methane ice: Temperature-dependent absorption coefficients of CH 3D in methane ice and in nitrogen ice
    The existence of strong absorption bands of singly deuterated methane (CH 3D) at wavelengths where normal methane (CH 4) absorbs comparatively weakly could enable remote measurement of D/H ratios in methane ice on outer Solar System bodies. We performed laboratory transmission spectroscopy experiments, recording spectra at wavelengths from 1 to 6 m to study CH 3D bands at 2.47, 2.87, and 4.56 m, wavelengths where ordinary methane absorption is weak. We report temperature-dependent absorption coefficients of these bands when the CH 3D is diluted in CH 4 ice and also when it is dissolved in N 2 ice, and describe how these absorption coefficients can be combined with data from the literature to simulate arbitrary D/H ratio absorption coefficients for CH 4 ice and for CH 4 in N 2 ice. We anticipate these results motivating new telescopic observations to measure D/H ratios in CH 4 ice on Triton, Pluto, Eris, and Makemake.
  103. Batalha, N., Borucki, W., Bryson, S., et al., (including Dunham, E.), 2011, ApJ, 729, 27, Kepler's First Rocky Planet: Kepler-10b
    NASA's Kepler Mission uses transit photometry to determine the frequency of Earth-size planets in or near the habitable zone of Sun-like stars. The mission reached a milestone toward meeting that goal: the discovery of its first rocky planet, Kepler-10b. Two distinct sets of transit events were detected: (1) a 152 4 ppm dimming lasting 1.811 0.024 hr with ephemeris T [BJD] =2454964.57375+0.00060 -0.00082 + N*0.837495+0.000004 -0.000005 days and (2) a 376 9 ppm dimming lasting 6.86 0.07 hr with ephemeris T [BJD] =2454971.6761+0.0020 -0.0023 + N*45.29485+0.00065 -0.00076 days. Statistical tests on the photometric and pixel flux time series established the viability of the planet candidates triggering ground-based follow-up observations. Forty precision Doppler measurements were used to confirm that the short-period transit event is due to a planetary companion. The parent star is bright enough for asteroseismic analysis. Photometry was collected at 1 minute cadence for >4 months from which we detected 19 distinct pulsation frequencies. Modeling the frequencies resulted in precise knowledge of the fundamental stellar properties. Kepler-10 is a relatively old (11.9 4.5 Gyr) but otherwise Sun-like main-sequence star with T eff = 5627 44 K, M sstarf = 0.895 0.060 M sun, and R sstarf = 1.056 0.021 R sun. Physical models simultaneously fit to the transit light curves and the precision Doppler measurements yielded tight constraints on the properties of Kepler-10b that speak to its rocky composition: M P = 4.56+1.17 -1.29 M , R P = 1.416+0.033 -0.036 R , and P = 8.8+2.1 -2.9 g cm-3. Kepler-10b is the smallest transiting exoplanet discovered to date.

    Based in part on observations obtained at the W. M. Keck Observatory, which is operated by the University of California and the California Institute of Technology.

  104. Barnes, S., Kim, Y., 2011, ApJ, 729, 150, Erratum: "Angular Momentum Loss from Cool Stars: An Empirical Expression and Connection to Stellar Activity" (2010, ApJ, 721, 675)
    No abstract found.
  105. Bullock, E., Szkody, P., Mukadam, A., et al., (including Levine, S.), 2011, AJ, 141, 84, GALEX and Optical Observations of GW Librae during the Long Decline from Superoutburst
    The prototype of accreting, pulsating white dwarfs (GW Lib) underwent a large amplitude dwarf nova outburst in 2007. We used ultraviolet data from Galaxy Evolution Explorer and ground-based optical photometry and spectroscopy to follow GW Lib for three years following this outburst. Several variations are apparent during this interval. The optical shows a superhump modulation in the months following outburst, while a 19 minute quasi-periodic modulation lasting for several months is apparent in the year after outburst. A long timescale (about 4 hr) modulation first appears in the UV a year after outburst and increases in amplitude in the following years. This variation also appears in the optical two years after outburst but is not in phase with the UV. The pre-outburst pulsations are not yet visible after three years, likely indicating the white dwarf has not returned to its quiescent state.

    Based on observations made with the NASA Galaxy Evolution Explorer and with the Apache Point Observatory (APO) 3.5 m telescope. GALEX is operated for NASA by the California Institute of Technology under NASA contract NAS5-98034. APO is owned and operated by the Astrophysical Research Consortium (ARC).

  106. Archinal, B., A'Hearn, M., Bowell, E., et al., 2011, CeMDA, 109, 101, Report of the IAU Working Group on Cartographic Coordinates and Rotational Elements: 2009
    Every three years the IAU Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report takes into account the IAU Working Group for Planetary System Nomenclature (WGPSN) and the IAU Committee on Small Body Nomenclature (CSBN) definition of dwarf planets, introduces improved values for the pole and rotation rate of Mercury, returns the rotation rate of Jupiter to a previous value, introduces improved values for the rotation of five satellites of Saturn, and adds the equatorial radius of the Sun for comparison. It also adds or updates size and shape information for the Earth, Mars' satellites Deimos and Phobos, the four Galilean satellites of Jupiter, and 22 satellites of Saturn. Pole, rotation, and size information has been added for the asteroids (21) Lutetia, (511) Davida, and (2867) Steins. Pole and rotation information has been added for (2) Pallas and (21) Lutetia. Pole and rotation and mean radius information has been added for (1) Ceres. Pole information has been updated for (4) Vesta. The high precision realization for the pole and rotation rate of the Moon is updated. Alternative orientation models for Mars, Jupiter, and Saturn are noted. The Working Group also reaffirms that once an observable feature at a defined longitude is chosen, a longitude definition origin should not change except under unusual circumstances. It is also noted that alternative coordinate systems may exist for various (e.g. dynamical) purposes, but specific cartographic coordinate system information continues to be recommended for each body. The Working Group elaborates on its purpose, and also announces its plans to occasionally provide limited updates to its recommendations via its website, in order to address community needs for some updates more often than every 3 years. Brief recommendations are also made to the general planetary community regarding the need for controlled products, and improved or consensus rotation models for Mars, Jupiter, and Saturn.
  107. Borucki, W., Koch, D., Basri, G., et al., (including Dunham, E.), 2011, ApJ, 728, 117, Characteristics of Kepler Planetary Candidates Based on the First Data Set
    In the spring of 2009, the Kepler Mission commenced high-precision photometry on nearly 156,000 stars to determine the frequency and characteristics of small exoplanets, conduct a guest observer program, and obtain asteroseismic data on a wide variety of stars. On 2010 June 15, the Kepler Mission released most of the data from the first quarter of observations. At the time of this data release, 705 stars from this first data set have exoplanet candidates with sizes from as small as that of Earth to larger than that of Jupiter. Here we give the identity and characteristics of 305 released stars with planetary candidates. Data for the remaining 400 stars with planetary candidates will be released in 2011 February. More than half the candidates on the released list have radii less than half that of Jupiter. Five candidates are present in and near the habitable zone; two near super-Earth size, and three bracketing the size of Jupiter. The released stars also include five possible multi-planet systems. One of these has two Neptune-size (2.3 and 2.5 Earth radius) candidates with near-resonant periods.
  108. Grundy, W., Roe, H., Trujillo, C., et al., (including Porter, S.), 2011, noao, 17, Mutual Orbits and Masses of Kuiper Belt Binaries and Multiple Systems
    The planetesimals in the Kuiper belt are a mixed group of survivors originating at different places in the proto-planetary nebula around the young Sun. They show a remarkable diversity of surface properties, but this heterogeneity remains to be understood in terms of formation in physically and chemically distinct nebular regions. Trans-neptunian binary and multiple systems can provide this link through measurement of their mutual orbits and masses, opening the door to a rich family of investigations that can probe bulk properties such as density and albedo, chemical composition, and internal structure. Binaries are a natural laboratory for a wealth of dynamical studies that can constrain conditions at the time of their formation as well as their subsequent evolution. But to realize their full potential to elucidate conditions in the proto-planetary nebula requires access to a large sample to tease apart the distinct influences of formation conditions and subsequent history. The natural time-dependence of this problem and the necessity of a large sample call for the investment of a survey program.
  109. Herrmann, K., Ciardullo, R., 2011, noao, 104, Planetary Nebula Kinematics in M101
    Look at a spiral; what do you see? Stars zooming `round in the galaxy! Their motions indicate total mass, but how much is DM, stars, and gas? Study motions in and out; first find monochromatic stars- that's my kind. Find us, get our velocities, then: determine disk mass! I'm a PN! Rotation curves indicate the total mass of spirals, but halo mass profiles cannot be decoupled from the visible disk mass using rotation curves alone. To break this disk-halo degeneracy, we have been using planetary nebulae (PNe) to measure the z-component of the stellar velocity dispersion in the disks of face-on spirals. These measurements of _z, coupled with straightforward assumptions, have yielded disk surface mass estimates over several scale lengths (h_R) in 6 spirals. We find that in the inner regions of galaxies (R < 3.5 h_R), the values of _z are consistent with those expected from a constant mass-to-light ratio (M/L), constant scale-height disk and this trend continues into the outer regions of M74 and IC 342. However, in M83 and M94, _z flattens and becomes constant with radius. We have interpreted this as evidence for satellite accretion with disk flaring, but an increasing disk M/L may also contribute to the behavior. To investigate this phenomenon more thoroughly, we are proposing to extend the survey of an additional galaxy, M101, to R > 8 h_R. Last year we imaged M101 with the wide-field Mosaic camera on the KPNO 4-m telescope. This proposal is to perform follow-up spectroscopy on ~240 PNe in M101 with WIYN/Hydra.
  110. Jackson, M., Hunter, D., Rubin, V., et al., 2011, noao, 116, The Stellar Kinematics of Dwarf Irregular Galaxy DDO 125: Is this a galaxy without dark matter?
    DDO 125 may contain little or no dark matter, according to some radio observations of the neutral hydrogen gas in the disk. However, no dark matter could be the result of assuming a maximum stellar disk but, we can find out about the real stellar disk from kinematics of the stars. If a turnover in the rotation of the stars is detected and the rotation of the stars is flat after the turnover point, then dark matter would be needed to explain the stellar rotation curve of DDO 125. If there is, in fact, no turnover point and the stars and the gas follow each other kinematically, then there may be little or no dark matter detectable in this system. This could indicate a different evolutionary history. There are recent studies that show stars and gas do not move in the same way, thus, it could be quite possible that the stars and the gas of DDO 125 do not follow each other. Therefore, we propose to use the KPNO 4-m+Echelle as a 3 arcmin longslit spectrograph to obtain the stellar kinematics of DDO 125. We will use a cross-correlation function to determine heliocentric radial velocities and velocity dispersions as a function of radius for the stellar disk of DDO 125 and compare these to the gas kinematics determined from newly acquired 21 cm VLA HI data.
  111. Roe, H., Schaller, E., Brown, M., et al., 2011, noao, 147, Titan's Methane Weather post-Equinox: Seasonal climate change and surface geology
    Recently in this program we discovered clouds in the north polar region that are formed via lake-effect processes (Brown et al. 2008) and observed a massive tropical storm that induced Rossby-wave clouds throughout the southern hemisphere (Schaller et al. 2009). Previously we discovered Titan's mid-latitude clouds (Roe et al. 2005a) and that their locations are controlled by surface processes, possibly including cryovolcanoes, geysering, and/or the opening of surface cracks (Roe et al. 2005b). We observed a massive storm engulfing the south pole (Schaller et al. 2006a) and found a near-disappearance of south polar cloud activity as the season moved further into southern summer (Schaller et al. 2006B). Observing Titan's clouds requires only a small amount (15-25 min) of large (8-10 meter) adaptive optics telescope time and queued Gemini observations are uniquely suited to this program. As Titan's northern spring progresses (equinox was in August 2009), continued observations are required to monitor the advance of the planetary scale monsoon, driving new clouds in the northern and southern polar regions, and identify and monitor regions of active surface geology.
  112. Young, L., Roe, H., Young, E., et al., 2011, noao, 301, Pluto's Atmospheric CH_4: Variations in time, space, and altitude
    We propose observations of gaseous methane on Pluto with GNIRS+AO at three specific sub-observer longitudes to (1) establish a baseline for temporal change, (2) search for spatial variability in gaseous methane, and (3) refine the vertical distribution of gaseous CH_4. The three longitudes, separated by roughly 120, correspond to the longitudes of minimum CH_4 frost, maximum CH_4 frost, and maximum ratio of nearly pure to highly diluted CH_4 frost. These three terrains are expected to produce detectable differences in the gaseous CH_4. These observations will provide a temporal and spatial context in which to place the New Horizons encounter with Pluto in 2015.
  113. Zhang, H., Hunter, D., Herrmann, K., et al., 2011, noao, 306, Deep JH Imaging of the LITTLE THINGS Galaxies: Stellar Mass Assembly in Dwarf Galaxies
    We propose to obtain deep broadband JH images for 6 dwarf irregular galaxies (dIm) which are part of a larger sample assembled by the LITTLE THINGS project (a VLA Large Proposal). Using the NIR data requested here and other multi-band data we have collected, we will, for the first time, construct high-quality spectral energy distributions (SEDs) covering the whole spectral range of stellar emission for a representative sample of dIm galaxies. dIm galaxies numerically dominate the local Universe, yet our understanding of the star formation processes in dIm galaxies is very poor. For example, the star formation rate profile often correlates closely with the stellar surface brightness profile of the older stars, but not with the gas, and we do not know why. Also, abrupt changes in the slope of the stellar exponential profile imply a change in the star formation process at the surface brightness breaks according to some models, but this has not been shown observationally. With the SEDs constructed as a function of radius within each galaxy and our stellar population synthesis technique, we will answer the questions: 1) How is the stellar mass across the disks assembled throughout the lifetime of dwarf irregular galaxies? 2) Are there corresponding surface mass density breaks at the surface brightness breaks seen in many dIm galaxies? And is there any difference in the stellar populations before and beyond the surface brightness breaks?
  114. Naud, M., Artigau, E., Malo, L., et al., (including Barman, T.), 2011, noao, 382, A Planet Search around Young-associations M dwarfs (PSYM survey)
    A comprehensive investigation of the formation and evolution of giant planets requires a thorough direct imaging search for planets around primaries of all masses. Currently, as published direct imaging surveys have focused on solar-type or more massive primaries, and since relatively few nearby young low-mass stars were known, low-mass stars are under-represented in the sample targeted by previous searches. Using a new Bayesian analysis that takes into account proper motion, sky position, chromospheric activity (Halpha and X-ray), photometry and radial-velocity, we have identified 160 new low mass (>M0) members of nearby young (<50 Myr) associations. Being young and nearby, these newly-identified members are ideal targets for direct imaging searches. We propose to observe this sample of new low-mass stars with NICI to search for self-luminous giant planets down to 2 Mjup at orbital separations of 15-500 AU. Our survey will nearly quadruple the number of young M-dwarfs probed for planets and will allow, for the first time, to place constraints on the existence of planets around low-mass stars at a level comparable to what has been done for more massive stars.
  115. Ciardullo, R., Jacoby, G., Feldmeier, J., et al., (including Herrmann, K.), 2011, noao, 466, The Distance to the Antennae Galaxy
    The Antennae Galaxy (NGC 4038/39) is a key member of the Toomre sequence of merging galaxies, and an important astrophysical laboratory for a host of exotic objects, such as ultra luminous x-ray sources, super star clusters, and tidal dwarf galaxies. Yet the distance to the system is extremely controversial, with recent estimates ranging from 13.3 Mpc (Saviane l 2008) to 22.3 Mpc (Schweizer l 2008). Since this uncertainty effects all our astrophysical measurements, it is vital that the question be settled. We propose to use the CTIO 4-m telescope to measure the Antennae Galaxy's distance using the Planetary Nebula Luminosity Function. By imaging the galaxy in [O III] (lambda) 5007, H(alpha), and in the continuum, we will be able to produce a definitive distance to this important system. We also note that if the galaxy is closer than ~ 15 Mpc, our survey will produce a large sample of PNe for a future kinematic study. This proposal is a resubmission of program 2009A-0272, which was mostly lost to clouds and extremely poor seeing. Only five hours of marginally useful data were acquired; these observations imply a distance D > 12 Mpc. To place a more interesting limit on the system's distance, more time (with at least close to median seeing!) is needed.
  116. Adams, E., Lopez-Morales, M., Elliot, J., et al., 2011, ApJ, 728, 125, Transit Timing Variation Analysis of OGLE-TR-132b with Seven New Transits
    We report the results of the first transit timing variation analysis of the very hot Jupiter OGLE-TR-132b, using 10 transits collected over a seven-year period. Our analysis combines three previously published transit light curves with seven new transits, which were observed between 2008 February and 2009 May with the new MagIC-e2V instrument on the Magellan Telescopes in Chile. We provide a revised planetary radius of Rp = 1.23 0.07RJ , which is slightly larger, but consistent within the errors, than that given by previously published results. Analysis of the planet-to-star radius ratio, orbital separation, inclination, and transit duration reveals no apparent variation in any of those parameters during the time span observed. We also find no sign of transit timing variations larger than -108 49 s, with most residuals very close to zero. This allows us to place an upper limit of 5-10 M for a coplanar, low-eccentricity perturber in either the 2:1 or 3:2 mean-motion resonance with OGLE-TR-132b. We similarly find that the data are entirely consistent with a constant orbital period and there is no evidence for orbital decay within the limits of precision of our data.

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

  117. Lissauer, J., Fabrycky, D., Ford, E., et al., (including Dunham, E.), 2011, Natur, 470, 53, A closely packed system of low-mass, low-density planets transiting Kepler-11
    When an extrasolar planet passes in front of (transits) its star, its radius can be measured from the decrease in starlight and its orbital period from the time between transits. Multiple planets transiting the same star reveal much more: period ratios determine stability and dynamics, mutual gravitational interactions reflect planet masses and orbital shapes, and the fraction of transiting planets observed as multiples has implications for the planarity of planetary systems. But few stars have more than one known transiting planet, and none has more than three. Here we report Kepler spacecraft observations of a single Sun-like star, which we call Kepler-11, that reveal six transiting planets, five with orbital periods between 10 and 47days and a sixth planet with a longer period. The five inner planets are among the smallest for which mass and size have both been measured, and these measurements imply substantial envelopes of light gases. The degree of coplanarity and proximity of the planetary orbits imply energy dissipation near the end of planet formation.
  118. Horch, E., Gomez, S., Sherry, W., et al., 2011, AJ, 141, 45, Observations of Binary Stars with the Differential Speckle Survey Instrument. II. Hipparcos Stars Observed in 2010 January and June
    The results of 497 speckle observations of Hipparcos stars and selected other targets are presented. Of these, 367 were resolved into components and 130 were unresolved. The data were obtained using the Differential Speckle Survey Instrument at the WIYN 3.5 m Telescope. (The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories.) Since the first paper in this series, the instrument has been upgraded so that it now uses two electron-multiplying CCD cameras. The measurement precision obtained when comparing to ephemeris positions of binaries with very well known orbits is approximately 1-2 mas in separation and better than 0fdg6 in position angle. Differential photometry is found to be in very good agreement with Hipparcos measures in cases where the comparison is most relevant. We derive preliminary orbits for two systems.
  119. Torres, G., Fressin, F., Batalha, N., et al., (including Dunham, E.), 2011, ApJ, 727, 24, Modeling Kepler Transit Light Curves as False Positives: Rejection of Blend Scenarios for Kepler-9, and Validation of Kepler-9 d, A Super-earth-size Planet in a Multiple System
    Light curves from the Kepler Mission contain valuable information on the nature of the phenomena producing the transit-like signals. To assist in exploring the possibility that they are due to an astrophysical false positive, we describe a procedure (BLENDER) to model the photometry in terms of a "blend" rather than a planet orbiting a star. A blend may consist of a background or foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated by the light of the candidate and possibly other stars within the photometric aperture. We apply BLENDER to the case of Kepler-9 (KIC 3323887), a target harboring two previously confirmed Saturn-size planets (Kepler-9 b and Kepler-9 c) showing transit timing variations, and an additional shallower signal with a 1.59 day period suggesting the presence of a super-Earth-size planet. Using BLENDER together with constraints from other follow-up observations we are able to rule out all blends for the two deeper signals and provide independent validation of their planetary nature. For the shallower signal, we rule out a large fraction of the false positives that might mimic the transits. The false alarm rate for remaining blends depends in part (and inversely) on the unknown frequency of small-size planets. Based on several realistic estimates of this frequency, we conclude with very high confidence that this small signal is due to a super-Earth-size planet (Kepler-9 d) in a multiple system, rather than a false positive. The radius is determined to be 1.64+0.19 -0.14 R , and current spectroscopic observations are as yet insufficient to establish its mass.
  120. Zhang, H., Hunter, D., LITTLE THINGS Team, 2011, AAS, 217, 147.13, Stellar Mass Distributions in Dwarf Irregular Galaxies
    We present the radial distributions of the stellar mass and the star formation histories for a large sample of dwarf irregular galaxies assembled by the LITTLE THINGS project (Local Irregulars That Trace Luminosity Extremes The HI Nearby Galaxy Survey,

    http://www.lowell.edu/users/dah/littlethings/index.html). Specifically, utilizing the multi-band data

    including FUV/NUV/UBV/H/3.6m, and with the CB07 stellar population synthesis models, we

    analyze the variations of the SEDs as a function of radius. By studying the relationship between the

    stellar mass, star formation histories, star formation and HI gas, we will discuss the possible star formation modes and the roles played by the stellar mass and gas in determining the star formation in dwarf irregular galaxies in general.

    We gratefully acknowledge funding for this research from the National Science Foundation (AST-0707563).

  121. Taylor, J., Massey, P., Drout, M., et al., 2011, AAS, 217, 153.16, The O I 7774 Line as a Luminosity Indicator in M31
    Yellow supergiants are very useful tools in determining the accuracy of current stellar evolutionary models. These stars represent a short phase in a supergiants life; typically they will live only thousands of years. Because of this, their positions on the H-R diagram can reveal errors in current models. Identifying stars as yellow supergiants, however, has proved difficult as foreground Milky Way dwarfs can have similar colors and magnitudes. Still, Drout et al. (2009) and Neugent et al. (2010) identified yellow supergiant members from foreground non-members by using stars radial velocities. How does one identify yellow supergiants in galaxies without significant rotational velocity, though? In an effort to answer this, we have turned our attention to the O I 7774 triplet. This line has been known to be a luminosity indicator in F-type supergiants due to Non-Local Thermal Equilibrium (LTE) and sphericity effects (Osmer 1972). We analyzed the spectra of 900 stars in M31, obtained with the Hectospec multi-fiber spectrometer on the MMT. This sample included 48 rank-1 (nearly certain) M31 members (Drout et al. 2009), looking specifically at the 7774 line. There was found to be a limit that determines what a significant amount of oxygen is, at approximately 1.2 A. We found that the majority of previously known rank-1s had a significant amount of oxygen, while 11% of rank-2s (probable yellow supergiants) and less than 1% of rank-3s (foreground dwarfs) had a significant amount. These results imply that the O I 7774 will indeed work as a luminosity indicator.

    This work was supported by the National Science Foundation through grants AST-1008020 and AST-1004107.

  122. Blaha, C., Johnson, T., Cawthon, R., et al., (including Massey, P.), 2011, AAS, 217, 251.12, H Survey of Emission Line Regions in M33 and Local Group Dwarf Galaxies
    We present the results of a survey of H emission line regions in M33 and seven dwarf galaxies in the Local Group (NGC6822, IC10, WLM, Sextans A and B, Phoenix and Pegasus). Using data from the Local Group Galaxy Survey (LGGS - see Massey et al, 2006)), we used continuum-subtracted H emission line images to define emission regions with a faint flux limit of 10 -17 ergs-sec-1-cm-2 above the background. We have obtained photometric measurements for over 4000 H emission regions in M33 and five of the seven dwarf galaxies. Using these regions, with boundaries defined by their H -emission, we also determined fluxes for the continuum-subtracted [OIII] and [SII] images and constructed a catalog of H fluxes, region sizes and [OIII]/ H and [SII]/ H line ratios. The HII region luminosity functions and size distributions for spiral galaxy M33 are compared with those of the dwarf galaxies NGC 6822 and IC10. For M33, the average [SII]/ H line ratios, plotted as a function of galactocentric radius, display a linear trend with a very shallow slope. The galaxy-wide averages of [SII]/ H line ratios correlate with the masses of the dwarf galaxies following the previously established dwarf galaxy mass-metallicity relationship. An interactive catalog of these LGGS emission line surveys will be made available on-line.
  123. Wright, T., Hunter, D., Rubin, V., 2011, AAS, 217, 258.32, Star Formation in the Outer Disks of Spiral Galaxies
    This is a study done in collaboration with Deidre Hunter at Lowell Observatory studying star formation in two luminous spiral galaxies NGC 801 and UGC 2885. We used ultra-deep H images taken at the KPNO 2.1 m telescope. We compare these data to stellar images at various wavelengths and to HI maps to determine the extent of star formation activity into the outer disk in these galaxies and its relationship to the gas and older stars.

    TW is grateful for an REU internship during the summer of 2010 at Northern Arizona University, funded by NSF through grant AST-1004107.

  124. Jackson, M., Hunter, D., Oh, S., et al., 2011, AAS, 217, 328.03, Understanding the Structure of NGC 1569 and Dwarf Irregular Galaxies
    NGC 1569 is a post-starburst dwarf irregular (dIm) galaxy located in the IC 342 galaxy group. It has 3 supermassive star clusters (SSCs) and is a well studied object in the literature. We present an in depth study of the kinematics of the stellar and gas disks of NGC 1569 and analyze the three dimensional shape of this dIm galaxy. There are three forms of data we use to determine the shape of this system. First, we obtained long-slit, high resolution spectroscopy of the stars in NGC 1569 using the KPNO 4-meter + Echelle spectrograph. For these stellar spectra, we used a filter that targets the Mg Ib absorption features. During one of our 4-meter+Echelle observing runs, we changed the filter to target the [OIII]5007A emission line. Using this filter, we observed radial velocities of the ionized gas in NGC 1569, the second form of data in our study. Thirdly, we used high spatial and high spectral resolution, 21 cm, VLA HI line data obtained by THINGS. These data were mapped using a multi-scale cleaning algorithm implemented in AIPS by the LITTLE THINGS team. The kinematics of the gas were obtained using a double Gaussian decomposition method to separate a bulk motion velocity field from random, non-circular motions. In addition to the kinematic study, we also present our results of a large, 9 x 2 HI emission map made using the Robert C. Byrd Green Bank Telescope. We detect large-scale HI structure around NGC 1569 indicative of possible interactions with IC 342 galaxy group members. We conclude the dissertation talk by highlighting two more dwarf irregular galaxies for which both stellar and gas kinematics have been obtained and analyzed. This research has been funded by the NSF LITTLE THINGS grant AST-0707563 and by the NRAO Student Observing Support award GSSP10-0001.
  125. Meynet, G., Georgy, C., Hirschi, R., et al., (including Massey, P.), 2011, BSRSL, 80, 266, Red Supergiants, Luminous Blue Variables and Wolf-Rayet stars: the single massive star perspective
    We discuss, in the context of the single star scenario, the nature of the progenitors of Red Supergiants (RSG), of Luminous Blue Variables (LBV) and of Wolf-Rayet (WR) stars. These three different populations correspond to evolved phases of Main-Sequence (MS) OB stars. Axial rotation and mass loss have a great influence on massive star evolution in general and more specifically on the durations of these different phases. Moderate rotation and mass loss, during the MS phase, favor the evolution towards the RSG stage. Fast rotation and strong mass loss during the MS phase, in contrast, prevent the star from becoming a RSG and allow the star to pass directly from the OB star phase into the WR phase. Mass loss during the RSG stage may make the star evolve back in the blue part of the HR diagram. We argue that such an evolution may be more common than presently accounted for in stellar models. This might be the reason for the lack of type IIP SNe with RSG progenitors having initial masses between 18 and 30 M_. The LBVs do appear as a possible transition phase between O and WR stars or between WNL and WNE stars. Fast rotation and/or strong mass loss during the Main-Sequence phase prevent the formation of LBV stars. The mechanisms driving the very strong ejections shown by LBV stars are still unknown. We present some arguments showing that axial rotation together with the proximity of the Eddington limit may play a role in driving the shell ejections. Rotation and mass loss favor the formation of Wolf-Rayet stars. The fact that WR stars and RSGs rarely occur in the same coeval populations indicates that the mass range of these two populations is different, WR stars originating from more massive stars than RSGs. Single star evolution models predict variations with the metallicity of the number ratios of Type Ibc to Type II supernovae, of Type Ib to Type II and of Type Ic to Type II, which are compatible with observations, provided that many stars leaving a black hole as a remnant produce an observable supernova event.
  126. Borucki, W., Koch, D., Gautier, T., et al., (including Dunham, E., Kepler Science Team), 2011, AAS, 217, 121.01, Kepler Mission Overview
    Early Kepler observations show the presence of over 750 candidate planets, 1800 eclipsing binary stars, and variable stars of amazing variety. Many of the planetary candidates are smaller than Neptune. Discoveries of seven new exoplanets are shown including one of with two confirmed transiting planets. The candidate- and the announced-planets are compared with known exoplanets with respect to mass, size, density, and orbital period.

    Support by the NASA Astrophysics Division is gratefully acknowledged.

  127. Bryson, S., Jenkins, J., Gilliland, R., et al., (including Dunham, E.), 2011, AAS, 217, 140.05, Pixel-Level Analysis Techniques for False-Positive Identification in Kepler Data
    The Kepler mission seeks to identify Earth-size exoplanets by detecting transits of their parent star. The resulting transit signature will be small ( 100 ppm). Several astrophysical phenomena can mimic an Earth-size transit signature, most notably background eclipsing binaries (BGEBs). As part of a larger false-positive identification effort, pixel-level analysis of the Kepler data has proven crucial in identifying the likelihood of these confounding signals. Pixel-level analysis is primarily useful for the case of the transit being a BGEB. Several analysis techniques are presented, including:

    - measurement of centroid motion in and out of transit compared with detailed modeling of expected centroid motion, including an estimate of the transit source location

    - transit source location determination through a high-precision PSF-fit of the difference between in- and out-of-transit pixels, directly measuring the location of the transit source

    - source location determination through fitting the observed summed flux time series (or the light curve derived from the transit model) to each pixel's time series data.

    These techniques have been automated and are being considered for inclusion in the Kepler Science Operations Center Data Analysis Pipeline. They are supplemented by various diagnostic plots of the Kepler data as well as comparison with background stars identified by the Kepler Follow-up Observing Program (FOP). The final determination of whether an observed transit is a false positive integrates several sources, including pixel-level analysis and FOP results. Pixel-level techniques can identify BGEBs that are separated from the Kepler target star by more than a certain radius, called the "radius of confusion". The determination of the radius of confusion, and the role it plays in assigning the probability of the transit being due to a planet, is briefly discussed. The statistics from the latest false-positive list are provided.

    Funding for this mission provided by NASA's Discovery Program Office, SMD.

  128. Prato, L., 2011, AAS, 217, 145.09, The Lowell Observatory Predoctoral Scholar Program
    Lowell Observatory is pleased to solicit applications for our Predoctoral Scholar Fellowship Program. Now beginning its fourth year, this program is designed to provide unique

    research opportunities to graduate students in good standing, currently enrolled at Ph.D. granting institutions. Lowell staff research spans a wide range of topics, from astronomical instrumentation, to icy bodies in our solar system, to exoplanet science, to stellar populations and dwarf irregular galaxies. First light with the observatory's

    new 4.2 meter Discovery Channel Telescope is expected in 2011, making this a particularly exciting time in our history. Student research is expected to lead to a thesis dissertation appropriate for graduation at the doctoral level at the student's home institution. Currently, five students are enrolled in our program; our first graduate completed the program in August, 2009. The Observatory provides competitive compensation and full benefits to student scholars. For more information, see http://www.lowell.edu/rsch/predoc.php and links therein.

    Applications for Fall 2011 are due by May 1, 2011.

  129. Hunter, D., Oh, S., Elmegreen, B., 2011, AAS, 217, 147.14, Gas, Stars, and Star Formation in Extreme Outer Disks of Dwarf Galaxies
    We compare deep optical images, deep ultraviolet images obtained with GALEX, and HI interferometric maps of five dwarf irregular galaxies in order to examine star formation in their outer disks. The V-band surface photometry, which extends to 29-30 mag/arcsec-squared, averages the star formation activity over the past Gyr for on-going star formation. The GALEX ultraviolet data provides information on star formation over the past 200 Myrs. The HI maps and cubes yield information on the gas surface densities and kinematics. We deconvolve the ordered rotation from non-ordered motions of the gas and compare with the stellar populations.

    This research has been funded by the Lowell Research Fund and by NASA/GALEX grant NNX08AL66G.

  130. Herrmann, K., Hunter, D., Zhang, H., et al., 2011, AAS, 217, 147.15, Broken Surface Brightness Profiles in Dwarf Galaxies
    Recently it has been well shown that there are three different surface brightness profile types in spiral galaxies: (I) the minority, where the light falls off with a single exponential; (II) truncated, the majority, where the light falls off with one exponential to a break radius and then falls off more steeply; and (III) anti-truncated, where the light falls off with a more shallow exponential beyond the break radius. Additionally, Bakos, Trujillo, & Pohlen (2008) showed that each type has a characteristic color trend with respect to the break location. In dwarf disk galaxies, however, there is a fourth type which is perhaps a special Type II case: the light profile is flat on the inside and then falls off exponentially beyond the break radius. We will show the different color trends for these four profile types from a large photometric study of dwarf disk galaxies and explore the ramifications of the differences between spirals and dwarfs.

    We gratefully acknowledge funding for this research from the National Science Foundation (AST-0707563).

  131. Herrmann, K., 2011, AAS, 217, 158.04, Amidst the Beauty of the Night Sky, Which of the Constellations am I?
    A well known constellation am I-

    I never set in the northern sky.

    Native Americans and Greeks, you see,

    Wrote legends when they recognized me.

    Two close stars still test for keen eyesight.

    Two point to the North Star - what a light!

    Look for my galaxies, you know where.

    I am ---- -----, the ----- ----!

    (If you've an answer you'd care to try,

    Or check out more riddles, please stop by!

    Note: All my astronomy riddles are copyrighted.)

  132. Massey, P., Neugent, K., Morrell, N., et al., 2011, AAS, 217, 242.07, Measuring the Masses of the Most Massive Stars
    The relationship between mass and luminosity is poorly determined for high mass stars, with stellar atmosphere analysis often yielding lower estimates of the masses than stellar evolutionary models predict. For the hottest massive stars in the Magellanic Clouds such differences can be as much as a factor of two. This "mass discrepancy" problem has been known for 15 years. During this time the physics of both the stellar atmosphere and stellar evolutionary models has improved considerably, but the problem still remains with us. We've concluded that resolving this discrepancy requires an observational approach.

    We have been determining the masses of the highest mass stars directly from Kepler's 3rd law using massive eclipsing binaries, and comparing these to what is predicted by stellar evolutionary tracks. To identify the sample, we have used four years of intensive queue observations on the SMARTS Yale and LCO Swope 1.0-m telescope. This photometry has allowed us to pick out appropriate systems, whose light-curves and periods indicate a good chance that the components are not interacting, and that the results will be representative of single stars. Follow-up spectroscopy has been carried out on the Magellan 6.5-m Baade and Clay telescopes using IMACS and MagE, respectively. We present our preliminary results here.

    This work has been funded in part through the National Science Foundation (AST-0506577) and NASA (HST GO-10612).

  133. Crockett, C., Mahmud, N., Prato, L., et al., 2011, AAS, 217, 253.13, Searching For The Youngest Planets With CSHELL
    We are using CSHELL at the IRTF to confirm the presence of giant planets in a sample of 1-3 Myr old T Tauri stars in the Taurus-Auriga low-mass star forming region. The presence of large, cool star spots makes this a challenging environment in which to conduct a traditional RV survey; optical RV amplitudes are typically hundreds of m/s from stellar activity alone. However, we can leverage the fact that spot-induced RV modulation is dependent of wavelength. We identify potential candidates based on initial optical observations obtained at McDonald Observatory, Kitt Peak, and through the Keck HIRES Archive. Bisector analysis helps us identify targets to continue observing in the K band where the spot noise is much lower. Companion-induced variability will have the same amplitude at both wavelengths. We present details on our methodology for determining NIR RVs using CSHELL; over a two year baseline, we achieve 60 m/s precision on RV standards. We also present progress in modeling how stellar parameters affect the optical-to-NIR RV contrast and analysis of several candidate planet hosts. Given the young ages of these targets, a positive detection will place one of the first observational constraints on the planet formation timescale.
  134. Mahmud, N., Crockett, C., Johns-Krull, C., et al., (including Prato, L.), 2011, AAS, 217, 253.14, Brown Dwarfs and Giant Planets Around Young Stars
    How dry is the brown dwarf (BD) desert at young ages? Previous radial velocity (RV) surveys have revealed that the frequency of BDs as close companions to solar-age stars in the field is extraordinarily low compared to the frequency of close planetary and stellar companions. Is this a formation or an evolutionary effect? Do close-in BDs form at lower rates, or are they destroyed by migration via interactions with a massive circumstellar disk, followed by assimilation into the parent star?

    To answer these questions, we are conducting an RV survey of 130 T Tauri stars in Taurus-Auriga (a few Myr old) and a dozen stars in the Pleiades (100 Myr old) to search for stellar reflex motions resulting from close substellar companions. Our goal is to measure the frequency of BDs at young ages. Detecting a higher frequency of BDs in young systems relative to the field will provide evidence for the migration theory as well as set limits on the migration timescale. Two additional goals are (1) to investigate the effect of star spots in young stars on RV observations, and (2) to detect the youngest-known giant exoplanet.

    We present results from the first few years of this survey. Strikingly, after completing observations of a third of our sample, we have yet to detect a single BD. Thus we can set limits on the dryness of the BD desert at young ages and shed light on the mysterious early lives of these objects.

  135. Marois, C., Macintosh, B., Konopacky, Q., et al., (including Barman, T.), 2011, AAS, 217, 302.01, Direct Imaging Discovery of a Fourth Planet at 15AU in the HR 8799 Planetary System
    We present the imaging discovery of a fourth planet at 0.376 arcsec (14.8 AU) projected separation from the young nearby star HR8799. This new object, designated HR8799e, is detected at Ks- and L-band wavelengths using the ADI observing technique with adaptive optics and the Keck II telescope on Mauna Kea. Over a 1-year baseline the object is confirmed as co-moving with the primary, revolving counter-clockwise like the three other known planets of this system, and it has similar brightness at Ks and L to HR8799c and d and hence likely similar mass, 10 times the mass of Jupiter. HR8799 has now been shown to possess the same number of gas giant planets as our Solar System, further adding to the various similarities between the two systems.
  136. Jensen-Clem, R., Elliot, J., Person, M., et al., (including Levine, S., Bright, L., Dunham, E.), 2011, AAS, 217, 306.05, A Search for Satellites of Kuiper Belt Object 55636 from the 2009 October 9 Occultation
    A world-wide observing campaign of 21 telescopes at 18 sites was organized by Elliot et al. (2010 Nature 465, 897) to observe the 2009 Oct. 9 stellar occultation of 2UCAC 41650964 (UCAC2 magnitude 13.1) by the Kuiper Belt object 55636 (visual magnitude 19.6). Integration times varied between 0.05 seconds at the Vatican Advanced Technology Telescope and 5 seconds at Mauna Kea mid-level. Data from the two sites that successfully observed the occultation (Haleakala and the Mauna Kea mid-level) were analyzed by Elliot et al. (2010) to determine the diameter and albedo of 55636. In this study, we use the entire data set to search for signatures of occultations by nearby satellites. One satellite previously discovered with occultation data is Neptune's moon Larissa, which was detected during Neptune's close approach to a star in 1982 (Reitsema et al. 1982). No satellites are found in this study, and upper limits will be reported on satellite radii within the volume probed (2 x 10-8 of the Hill Sphere). This work was supported, in part, by NASA Grants NNX10AB27G (MIT), NNX08AO50G (Williams College), and NNH08AI17I (USNO-FS) and NSF Grant AST-0406493 (MIT). Student participation was supported in part by NSF's REU program and NASA's Massachusetts Space Grant.
  137. Karnath, N., Prato, L., Wasserman, L., 2011, AAS, 217, 340.18, Orbital Parameters for a Pre-Main Sequence Binary System
    The young system VSB 111 was originally classified as a single-lined spectroscopic binary in the star forming region of NGC 2264. Using the Keck II telescope we measured radial velocities for both the primary and secondary components in the infrared. By combining these data with previous visible light observations of the primary star, we derived the period, eccentricity, and other orbital parameters, as well as the mass ratio of the system. With additional information gained from further observations, for example the inclination derived from the angularly resolved orbit, we will eventually obtain the individual stellar masses, necessary to help to calibrate models of young star evolution. Furthermore, by compiling dozens or even hundreds of mass ratios for young binaries we can use mass ratio distributions to improve our understanding of binary star formation. No infrared excess or any other indication of a circumstellar disk is in evidence for VSB 111, indicating that either the accretion rate has dropped to an undetectable value or that this system has aged enough that its disk has dissipated, if originally present. Given the approximately 900 day period of this system, and its relatively high eccentricity, 0.8, the action of the companion could have been responsible for early dissipation of any disk material.
  138. Prato, L., 2011, AAS, 217, 340.23, Young Star Spectroscopic Binary Mass Ratios
    Mass is the most fundamental stellar parameter. For a given composition, a star's mass determines the character and duration of its entire life and the manner of its death. Accurate and precise masses comprise the underpinnings of stellar astrophysics, from the mass-luminosity relation, to models of pre-main sequence evolution. Mass ratio distributions of young stars directly test models of binary star formation. I will describe the progress made over the past decade in using infrared, high-resolution spectroscopy of young spectroscopic binaries in nearby star forming regions to determine pre-main sequence stellar mass ratios and masses, highlighting the past and ongoing contributions of many student collaborators. This presentation will include the most up to date results for the dynamically determined mass ratio distribution, case studies of the most intriguing young systems, and a preview of a new program to triple the number of precisely known pre-main sequence spectroscopic binary mass ratios.
  139. DeRoo, C., Prato, L., Skiff, B., et al., 2011, AAS, 217, 343.01, Determining Rotational Periods with Relative Photometry: V836 Tauri & BP Tauri
    Rotational periods for the T Tauri stars V836 Tau and BP Tau were determined using relative photometry in the B, V, and R filters. A rotational period of 7.0 days for V836 Tau was found and is consistent with other published periods. This variation in flux is likely caused by a combination of hot and cool spots on the star's surface. Initial analysis of one week's worth of data for the young star BP Tau revealed a rotational period of approximately 5.6 days; with the inclusion of all our data sets taken over 4 years we will obtain a more robust result. This research is part of a larger program with the goal of searching for exoplanets around stars in the Taurus-Auriga association. By comparing photometric rotation periods with radial velocity periods, variability caused by exoplanets rather than star spots can be identified. This research was supported by NSF grant number AST-1004107.
  140. Jensen, A., Redfield, S., Cochran, W., et al., (including Barman, T.), 2011, AAS, 217, 343.06, The Wesleyan Hobby-Eberly High-resolution Exoplanetary Atmospheric Transmission Spectroscopy Survey (W[HE]2ATS2): First Results
    We present the first results of W[HE]2ATS2 (The Wesleyan Hobby-Eberly High-resolution Exoplanetary Atmospheric Transmission Spectroscopy Survey). To date, this survey has collected approximately 90 hours worth of high-resolution (R 60k) ground-based optical spectra with the 9.2m Hobby-Eberly Telescope, with additional observations in progress. The survey includes five different solar-type stellar systems with transiting hot Jupiters or Neptunes. Spectra are taken both in and out of transit; the two categories of observations are each coadded with the resulting coadded spectra differenced to search for absorption from resonance lines of alkali metals that are expected in these atmospheres. We will present our confirmation of previous detections of Na I absorption in HD 189733 and HD 209458 and present upper limits on and possible new detections of Na I and K I in these and other targets. In addition, we will describe the details and challenges of our data reduction and analysis. Finally, we will discuss our prospects for future work in searching for additional alkali metal lines and exospheric absorption. This work is supported by the National Science Foundation through an Astronomy and Astrophysics Research Grant (AST-0903573). The Hobby-Eberly Telescope is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universitat Munchen, and Georg-August-Universitat Gottingen and is named in honor of its principal benefactors, William P. Hobby and Robert E. Eberly.
  141. Konopacky, Q., Macintosh, B., Marois, C., et al., (including Barman, T.), 2011, AAS, 217, 343.08, Orbital Analysis of the HR 8799 Planetary System: Astrometric Characterization and Improvements
    We present new results on the potential orbital configuration of the HR 8799 planetary system. New astrometric analysis of imaging data from NIRC2 on the Keck II telescope has allowed us to correct biases in the astrometry caused primarily by the camera's focal plane mask. Correcting these biases has significantly improved the orbit fits to our astrometry. We use these fits, along with other information uncovered in new 2010 datasets, to shed light on the stability of this system over long timescales. Portions of this work were performed

    under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work is supported by the NASA Origins Program.

  142. Macintosh, B., Barman, T., Konopacky, Q., et al., 2011, AAS, 217, 418.04, Near-ir Spectra Of The Planets HR8799b And HR8799c
    The directly-imaged HR8799 system represents a unique window into exoplanet formation and evolution with three massive coeval planets accesible to characterization using adaptive optics on modern telescopes. One such window is spectroscopic characterization. We have used the OSIRIS near-IR integral field spectrograph on the W.M. Keck telescope to study the two outermost planets. Taking advantage of the 3-dimensional OSIRIS data product we can separate artifact speckles noise from the true planetary signal. H and K band spectra of these two planets, among the coldest planetary bodies ever characterized, significantly diverge from observed brown dwarfs and older models of planetary atmospheres, with evidence for thick clouds and an absence of strong methane absorption in spite of their low (<1100K) effective temperatures.

    Portions of this work prepared by LLNL under Contract DE-AC52-07NA27344 and under support from the NASA Origins program.

  143. Barman, T., Macintosh, B., Konopacky, Q., et al., 2011, AAS, 217, 418.05, Atmospheric Properties Of The Young Exoplanets Hr 8799 b And c
    The HR 8799 planetary system provides a unique opportunity to study the atmospheric properties of three young, coeval, planets at the extreme high-mass range of planet formation. We will compare broad-band near-IR spectra of the two outermost planets, c and b, to model atmospheres. In addition to their bulk properties (effective temperature, surface gravity, and size), the level of cloud coverage and departure from a chemical equilibrium CO/CH4 ratio will be discussed. Our effective temperature estimates also disagree, by several hundred Kelvin, with standard interior cooling-track predictions for the estimated age and measured luminosities of these planets. Possible sources of this disagreement will be presented.
  144. Tsvetanov, Z., Anglada-Esqude, G., McCullough, P., et al., (including Mandushev, G.), 2011, AAS, 217, 429.07, Search for Exoplanets Transiting Bright Stars using Existing Space-based Data
    At the current stage of research transiting exoplanets are the only targets that allow determination of many of the key planetary parameters. In this respect the exceptionally high value of TEPs with bright parent stars is well recognized by the scientific community and several missions to perform a wide area space-based transit survey have been proposed. Here we describe a project that partially addresses this issue by using the existing data from one of the instruments on the currently operating space mission STEREO.

    STEREO is the third mission in NASA's Solar Terrestrial Probes program. It uses two nearly identical spacecrafts - one on Earth-leading orbit and one on Earth-trailing orbit - each equipped with a suit of five small telescopes to provide a stereoscopic view of the coronal mass ejections as they propagate away from the Sun. As each of these telescopes observes a portion of the heliosphere, they also image the star field in the background. The continuous series of images obtained by the HI-1 instruments are well suited for searching for transiting exoplanets with bright host stars. In one orbit of the satellites the HI-1 images cover a band of 10 around the ecliptic (18% of the sky). The photometric data series have the sensitivity to detect transiting hot Jupiters and other gas giants with periods up to 20 days and even some Neptune size planets orbiting bright and/or late type stars. On the extreme bright end, the survey is sensitive to some super-Earth size planets, but the available number of target stars is small. A large number of eclipsing binaries and variable stars is also revealed.

    This poster will describe the capabilities and limitations of the project and will present preliminary analysis of the existing data for RV discovered planets and an interesting eclipsing binary system.

  145. Rosero, V., Prato, L., Wasserman, L., et al., 2011, AJ, 141, 13, Orbital Solutions for Two Young, Low-mass Spectroscopic Binaries in Ophiuchus
    We report the orbital parameters for ROXR1 14 and RX J1622.7-2325Nw, two young, low-mass, and double-lined spectroscopic binaries recently discovered in the Ophiuchus star-forming region. Accurate orbital solutions were determined from over a dozen high-resolution spectra taken with the Keck II and Gemini South telescopes. These objects are T Tauri stars with mass ratios close to unity and periods of ~5 and ~3 days, respectively. In particular, RX J1622.7-2325Nw shows a non-circularized orbit with an eccentricity of 0.30, higher than any other short-period pre-main-sequence (PMS) spectroscopic binary known to date. We speculate that the orbit of RX J1622.7-2325Nw has not yet circularized because of the perturbing action of a ~1'' companion, itself a close visual pair. A comparison of known young spectroscopic binaries (SBs) and main-sequence (MS) SBs in the eccentricity-period plane shows an indistinguishable distribution of the two populations, implying that orbital circularization occurs in the first 1 Myr of a star's lifetime. With the results presented in this paper we increase by ~4% the small sample of PMS spectroscopic binary stars with known orbital elements.
  146. Massey, P., Olsen, K., Hodge, P., et al., (including McNeill, R., Strong, S.), 2011, AJ, 141, 28, Erratum: "A Survey of Local Group Galaxies Currently Forming Stars. II. UBVRI Photometry of Stars in Seven Dwarfs and a Comparison of the Entire Sample" (2007, AJ, 133, 2393)
    No abstract found.
  147. Agudo, I., Jorstad, S., Marscher, A., et al., (including Taylor, B.), 2011, ApJL, 726, L13, Location of -ray Flare Emission in the Jet of the BL Lacertae Object OJ287 More than 14 pc from the Central Engine
    We combine time-dependent multi-waveband flux and linear polarization observations with submilliarcsecond-scale polarimetric images at = 7 mm of the BL Lacertae type blazar OJ287 to locate the -ray emission in prominent flares in the jet of the source >14 pc from the central engine. We demonstrate a highly significant correlation between the strongest -ray and millimeter-wave flares through Monte Carlo simulations. The two reported -ray peaks occurred near the beginning of two major millimeter-wave outbursts, each of which is associated with a linear polarization maximum at millimeter wavelengths. Our very long baseline array observations indicate that the two millimeter-wave flares originated in the second of two features in the jet that are separated by >14 pc. The simultaneity of the peak of the higher-amplitude -ray flare and the maximum in polarization of the second jet feature implies that the -ray and millimeter-wave flares are cospatial and occur >14 pc from the central engine. We also associate two optical flares, accompanied by sharp polarization peaks, with the two -ray events. The multi-waveband behavior is most easily explained if the -rays arise from synchrotron self-Compton scattering of optical photons from the flares. We propose that flares are triggered by interaction of moving plasma blobs with a standing shock. The -ray and optical emission is quenched by inverse Compton losses as synchrotron photons from the newly shocked plasma cross the emission region. The millimeter-wave polarization is high at the onset of a flare, but decreases as the electrons emitting at these wavelengths penetrate less polarized regions.
  148. Knight, M., Farnham, T., Schleicher, D., et al., 2011, AJ, 141, 2, The Increasing Rotation Period of Comet 10P/Tempel 2
    We imaged comet 10P/Tempel 2 on 32 nights from 1999 April through 2000 March. R-band light curves were obtained on 11 of these nights from 1999 April through 1999 June, prior to both the onset of significant coma activity and perihelion. Phasing of the data yields a double-peaked light curve and indicates a nucleus rotational period of 8.941 0.002 hr with a peak-to-peak amplitude of ~0.75 mag. Our data are sufficient to rule out all other possible double-peaked solutions as well as the single- and triple-peaked solutions. This rotation period agrees with one of five possible solutions found in post-perihelion data from 1994 by Mueller and Ferrin (Icarus, 123, 463-477) and unambiguously eliminates their remaining four solutions. We applied our same techniques to published light curves from 1988 which were obtained at an equivalent orbital position and viewing geometry as in 1999. We found a rotation period of 8.932 0.001 hr in 1988, consistent with the findings of previous authors and incompatible with our 1999 solution. This reveals that Tempel 2 spun-down by ~32 s between 1988 and 1999 (two intervening perihelion passages). If the spin-down is due to a systematic torque, then the rotation period prior to perihelion during the 2010 apparition is expected to be an additional 32 s longer than in 1999.
  149. Sheehan, W., Boudreau, J., Manara, A., 2011, MmSAI, 82, 358, A figure in the carpet: Giovanni Schiaparelli's classic observations of Mercury reconsidered in the light of modern CCD images
    Though best known for his observations of Mars, Giovanni Virginio Schiaparelli also undertook a prolonged series of observations of Mercury leading to a rotation period for the planet that was repeatedly confirmed by later astronomers and would remain the standard for almost seven decades. In 1965, his result was shown to be mistaken. This study of Schiaparelli's drawings and notes in his observing log books in the light of CCD images allows a comprehensive understanding of how Schiaparelli reached the conclusions he did and provides insights into the difficulties of planetary studies in the visual era.

    150. 149 publications and 8282 citations in 2011.

149 publications and 8282 citations total.

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