Mapping the Galactic Disk with the LAMOST and Gaia Red Clump Sample. I. Precise Distances, Masses, Ages, and 3D Velocities of ∼140,000 Red Clump Stars

Abstract

Abstract We present a sample of ∼140,000 primary red clump (RC) stars of spectral signal-to-noise ratios higher than 20 from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) Galactic spectroscopic surveys, selected based on their positions in the metallicity-dependent effective temperature–surface gravity and color–metallicity diagrams, supervised by high-quality Kepler asteroseismology data. The stellar masses and ages of those stars are further determined from the LAMOST spectra, using the kernel principal component analysis method and are trained with thousands of RCs in the LAMOST–Kepler fields with accurate asteroseismic mass measurements. The purity and completeness of our primary RC sample are generally higher than 80%. For the mass and age, a variety of tests show typical uncertainties of 15% and 30%, respectively. Using over 10,000 primary RCs with accurate distance measurements from the parallaxes of Gaia Data Release 2 (DR2), we recalibrate the K s absolute magnitudes of primary RCs by, for the first time, considering both the metallicity and age dependencies. With the the new calibration, distances are derived for all the primary RCs, with a typical uncertainty of 5–10%, which is even better than the values yielded by the Gaia parallax measurements for stars beyond 3–4 kpc. The sample covers a significant volume of the Galactic disk of 4 ≤ R ≤ 16 kpc, , and −20 ≤ ϕ ≤ 50°. Stellar atmospheric parameters, line-of-sight velocities, and elemental abundances derived from the LAMOST spectra and proper motions of Gaia DR2 are also provided for the sample stars. Finally, the selection function of the sample is carefully evaluated in the color–magnitude plane for different sky areas. The sample is publicly available at 10.5281/zenodo.3875974.