Stars in the local galactic thick disc and halo in Gaia EDR3: a catalogue of half a million local main-sequence stars with photometric metallicities. Issue 3 (22nd December 2021)

• Record Type: Journal Article
• Authors: Kim, Bokyoung; Lépine, Sebastien
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 510:Issue 3(2022)
• Page Start: 4308
• Page End: 4329
• Publication Date: 2021-12-22
• Subjects: catalogues -- stars: abundances -- stars: kinematics and dynamics -- Galaxy: halo -- Galaxy: solar neighbourhood; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stab3671
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We present a catalogue of 551 214 main-sequence stars in the local ( d < 2 kpc) Galactic thick disc and halo, based on a search of stars with large proper motions ($\mu _{\rm tot} \gt 40.0~\rm mas\, yr^{-1}$ ) in the Gaia Early Data Release 3. We derive photometric metallicity calibrated from the colour–luminosity–metallicity distribution of 20 047 stars with spectroscopic metallicities, collected from various spectroscopic surveys, including SDSS SEGUE/APOGEE, GALAH DR3, and LAMOST DR6. We combine these results to construct an empirical colour–magnitude–metallicity grid, which can be used to estimate photometric metallicities for low-mass metal-poor stars of K and M subtypes from their absolute G magnitude and colour values. We find that low-mass, high-velocity stars in our catalogue share similar kinematics as reported in recent studies of more luminous Galactic halo stars. The pseudo-kinematic analysis of our sample recovers the main local halo structures, including the Gaia–Enceladus Stream and the Helmi stream; aside from these, the local halo stars appear to show a remarkably smooth distribution in velocity space. Since the future Gaia data release will provide radial velocity measurements for only a small number of our sample, our catalogue provides targets of high interest for the future spectroscopic observation programs.