Bayesian distances and extinctions for giants observed by Kepler and APOGEE

Rodrigues, Tha and Girardi, L. and Miglio, Andrea and Bossini, Diego and Bovy, Jo and Epstein, Courtney and Pinsonneault, Marc H. and Stello, Dennis and Zasowski, Gail and Prieto, Carlos Allende and Chaplin, William J. and Hekker, Saskia and Johnson, Jennifer A. and Mészáros, Szabolcs and Mosser, Beno and Anders, Friedrich and Basu, Sarbani and Beers, Timothy C. and Chiappini, Cristina and da Costa, Luiz A. N. and Elsworth, Yvonne and Garcia, R. A. and Hearty, Fred R. and Maia, Marcio A. G. and Majewski, Steven R. and Mathur, Savita and Montalban, J. and Nidever, David L. and Santiago, Basilio and Schultheis, Mathias (2014) Bayesian distances and extinctions for giants observed by Kepler and APOGEE. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 445 (3). pp. 2758-2776. ISSN 0035-8711

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Abstract

We present a first determination of distances and extinctions for individual stars in the first release of the APOKASC catalogue, built from the joint efforts of the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and the Kepler Astero- seismic Science Consortium (KASC). Our method takes into account the spectroscopic constraints derived from the APOGEE Stellar Parameters and Chemical Abundances Pipeline, together with the asteroseismic parameters from KASC. These parameters are then employed to estimate intrinsic stellar properties, including absolute magni- tudes, using the Bayesian tool PARAM. We then find the distance and extinction that best fit the observed photometry in SDSS, 2MASS, and WISE passbands. The first 1989 giants targeted by APOKASC are found at typical distances between 0.5 and 5 kpc, with individual uncertainties of just ∼ 1.8 per cent. Our extinction estimates are systematically smaller than provided in the Kepler Input Catalogue and by the Schlegel, Finkbeiner & Davis maps. Distances to individual stars in the NGC 6791 and NGC 6819 star clusters agree to within their credible intervals. Comparison with the APOGEE red clump and SAGA catalogues provide another useful check, exhibiting agreement with our measurements to within a few percent. Overall, present methods seem to provide excellent distance and extinction determinations for the bulk of the APOKASC sample. Approximately one third of the stars present broad or multiple- peaked probability density functions and hence increased uncertainties. Uncertainties are expected to be reduced in future releases of the catalogue, when a larger fraction of the stars will have seismically-determined evolutionary status classifications.

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