Gaia calibrated UV luminous stars in LAMOST

Abstract

We take advantage of Gaia Data Release 2 to present 275 and 1774 ultraviolet luminous stars in the far ultraviolet (FUV) and near ultraviolet (NUV), respectively. These stars exceed their expected values by 5σ with respect to over one million ultraviolet stars in the log g vs. T _eff diagram. Galactic extinction is corrected with a 3D dust map. In order to limit the Lutz-Kelker bias to an insignificant level, we select stars with relative uncertainties in luminosity less than 40% and trigonometric parallaxes less than 20%. We cross-identified our sample with the catalogs of RR Lyr stars and possible white dwarf main-sequence binaries, and find they compose ∼62% and ∼16% of our sample in the FUV and NUV, respectively. This catalog provides a unique sample to study stellar activity, spectrally unresolved compact main-sequence binaries and variable stars.