Browsing by Subject "sky survey 2mass"

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    The APOGEE Red-Clump Catalog: Precise Distances, Velocities, And High-Resolution Elemental Abundances Over A Large Area Of The Milky Way's Disk
    (2014-08) Bovy, Jo; Nidever, David L.; Rix, Hans-Walter; Girardi, Leo; Zasowski, Gail; Chojnowski, S. Drew; Holtzman, Jon; Epstein, Courtney; Frinchaboy, Peter M.; Hayden, Michael R.; Rodrigues, Thaise S.; Majewski, Steven R.; Johnson, Jennifer A.; Pinsonneault, Marc H.; Stello, Dennis; Prieto, Carlos Allende; Andrews, Brett; Basu, Sarbani; Beers, Timothy C.; Bizyaev, Dmitry; Burton, Adam; Chaplin, William J.; Cunha, Katia; Elsworth, Yvonne; Garcia, Rafael A.; Garcia-Hernandez, Domingo A.; Garcia Perez, Ana E.; Hearty, Fred R.; Hekker, Saskia; Kallinger, Thomas; Kinemuchi, Karen; Koesterke, Lars; Meszaros, Szabolcs; Mosser, Benoit; O'Connell, Robert W.; Oravetz, Daniel; Pan, Kaike; Robin, Annie C.; Schiavon, Ricardo P.; Schneider, Donald P.; Schultheis, Mathias; Serenelli, Aldo; Shetrone, Matthew; Aguirre, Victor Silva; Simmons, Audrey; Skrutskie, Michael; Smith, Verne V.; Stassun, Keivan; Weinberg, David H.; Wilson, John C.; Zamora, Olga; Shetrone, Matthew
    The Sloan Digital Sky Survey III's Apache Point Observatory Galactic Evolution Experiment (APOGEE) is a high-resolution near-infrared spectroscopic survey covering all of the major components of the Galaxy, including the dust-obscured regions of the inner Milky Way disk and bulge. Here we present a sample of 10,341 likely red-clump stars (RC) from the first two years of APOGEE operations, selected based on their position in color-metallicity-surface-gravity-effective-temperature space using a new method calibrated using stellar evolution models and high-quality asteroseismology data. The narrowness of the RC locus in color-metallicity-luminosity space allows us to assign distances to the stars with an accuracy of 5%-10%. The sample extends to typical distances of about 3 kpc from the Sun, with some stars out to 8 kpc, and spans a volume of approximately 100 kpc(3) over 5 kpc less than or similar to R less than or similar to 14 kpc, vertical bar Z vertical bar less than or similar to 2 kpc, and -15 degrees less than or similar to Galactocentric azimuth less than or similar to 30 degrees. The APOGEE red-clump (APOGEE-RC) catalog contains photometry from the Two Micron All Sky Survey, reddening estimates, distances, line-of-sight velocities, stellar parameters and elemental abundances determined from the high-resolution APOGEE spectra, and matches to major proper motion catalogs. We determine the survey selection function for this data set and discuss how the RC selection samples the underlying stellar populations. We use this sample to limit any azimuthal variations in the median metallicity within the approximate to 45 degrees azimuthal region covered by the current sample to be <= 0.02 dex, which is more than an order of magnitude smaller than the radial metallicity gradient. This result constrains coherent non-axisymmetric flows within a few kiloparsecs from the Sun.
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    A Technique To Derive Improved Proper Motions For Kepler Objects Of Interest
    (2014-12) Benedict, G. Fritz; Tanner, Angelle M.; Cargile, Phillip A.; Ciardi, David R.; Benedict, G. Fritz
    We outline an approach yielding proper motions with higher precision than exists in present catalogs for a sample of stars in the Kepler field. To increase proper-motion precision, we combine first-moment centroids of Kepler pixel data from a single season with existing catalog positions and proper motions. We use this astrometry to produce improved reduced-proper-motion diagrams, analogous to a Hertzsprung-Russell (H-R) diagram, for stars identified as Kepler objects of interest. The more precise the relative proper motions, the better the discrimination between stellar luminosity classes. Using UCAC4 and PPMXL epoch 2000 positions (and proper motions from those catalogs as quasi-Bayesian priors), astrometry for a single test Channel (21) and Season (0) spanning 2 yr yields proper motions with an average per-coordinate proper-motion error of 1.0 mas yr(-1), which is over a factor of three better than existing catalogs. We apply a mapping between a reduced-proper-motion diagram and an H-R diagram, both constructed using Hubble Space Telescope parallaxes and proper motions, to estimate Kepler object of interest K-band absolute magnitudes. The techniques discussed apply to any future small-field astrometry as well as to the rest of the Kepler field.