Ages and masses of million Galactic disk main sequence turn-off and sub-giant stars from the LAMOST Galactic spectroscopic surveys

Abstract

We present estimates of stellar age and mass for 0.93 million Galactic disk main sequence turn-off and sub-giant stars from the LAMOST Galactic Spectroscopic Surveys. The ages and masses are determined by matching with stellar isochrones using Bayesian algorithm, utilizing effective temperature $T_{\mathrm{eff}}$, absolute magnitude ${\mathrm{M}}_V$, metallicity [Fe/H] and $\alpha$-element to iron abundance ratio [$\alpha$/Fe] deduced from the LAMOST spectra. Extensive examinations suggest the age and mass estimates are robust. The overall sample stars have a median error of 34 per cent for the age estimates, and half of the stars older than 2\,Gyr have age uncertainties of only 20--30 per cent. Median error for the mass estimates of the whole sample stars is $\sim 8$ per cent. The huge dataset demonstrates good correlations among stellar age, [Fe/H] ([$\alpha$/H]) and [$\alpha$/Fe]. Particularly, double sequence features are revealed in the both the age--[$\alpha$/Fe] and age--[Fe/H]([$\alpha$/H]) spaces. In the [Fe/H]--[$\alpha$/Fe] space, stars of 8--10\,Gyr exhibit both the thin and thick disk sequences, while younger (older) stars show only the thin (thick) disk sequence, indicating that the thin disk became prominent 8--10\,Gyr ago, while the thick disk formed earlier and almost quenched 8\,Gyr ago. Stellar ages exhibit positive vertical and negative radial gradients across the disk, and the outer disk of $R\gtrsim$\,9\,kpc exhibits a strong flare in stellar age distribution.

22 pages, 24 figures; Accepted for publication in ApJS

References in corpus (21)

• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• The Dartmouth Stellar Evolution Database
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• Structure and Evolution of Nearby Stars with Planets II. Physical Properties of ~1000 Cool Stars from the SPOCS Catalog
• On the Formation of Galactic Thick Disks
• The LAMOST Stellar Parameter Pipeline at Peking University --- LSP3
• LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC): target selection and the first release of value-added catalogues
• Mass transfer from a giant star to a main sequence companion and its contribution to long-orbital-period blue stragglers
• Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis
• A radial age gradient in the geometrically thick disk of the Milky Way
• LAMOST Spectroscopic Survey of the Galactic Anticentre (LSS-GAC): the second release of value-added catalogues
• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• A large sample of calibration stars for Gaia: log g from Kepler and CoRoT
• The binarity of Milky Way F,G,K stars as a function of effective temperature and metallicity
• Stellar loci II. a model-free estimate of the binary fraction for field FGK stars
• Binary coalescence from case A evolution -- mergers and blue stragglers
• The old open clusters Berkeley 32 and King 11
• Relative Flux Calibration of the LAMOST Spectroscopic Survey of the Galactic Anti-center
• Bayesian Investigation of Isochrone Consistency Using the Old Open Cluster NGC 188
• The old anticentre open cluster Berkeley 32: membership and fundamental parameters

Cited by in corpus (37)

• A time-resolved picture of our Milky Way's early formation history
• A Giant Planet Candidate Transiting a White Dwarf
• Overview of the LAMOST survey in the first decade
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample: I: precise distances, masses, ages and 3D velocities of $\sim$ 140000 red clump stars
• Beyond spectroscopy. I. Metallicities, distances, and age estimates for over twenty million stars from SMSS DR2 and Gaia EDR3
• Ages and Masses of 0.64 million Red Giant Branch stars from the LAMOST Galactic Spectroscopic Survey
• Quantifying radial migration in the Milky Way: Inefficient over short timescales but essential to the very outer disc beyond ~15 kpc
• Hot subdwarf Atmospheric parameters, Kinematics, and Origins -- Based on 1587 hot subdwarf stars observed in Gaia DR2 and LAMOST DR7
• Planets Across Space and Time (PAST). I. Characterizing the Memberships of Galactic Components and Stellar Ages: Revisiting the Kinematic Methods and Applying to Planet Host Stars
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. VI: An evidence for the long lived non-steady warp of non-gravitational scenarios
• Radial structure and formation of the Milky Way disc
• A variational encoder-decoder approach to precise spectroscopic age estimation for large Galactic surveys
• Planets Across Space and Time (PAST). V. The evolution of hot Jupiters revealed by the age distribution of their host stars
• From large-scale environment to CGM angular momentum to star forming activities -- I: star-forming galaxies
• Milky Way Analogues in MaNGA: Multi-Parameter Homogeneity and Comparison to the Milky Way
• The Flattening Metallicity Gradient in the Milky Way's Thin Disk
• The Galactic disc phase spirals at different Galactic positions revealed by Gaia and LAMOST data
• On the Flaring of Thick Disc of Galaxies: Insights from Simulations
• Hot Subdwarf Stars Identified in Gaia DR2 with Spectra of LAMOST DR6 and DR7. II. Kinematics
• A kinematic calibration of the O-rich Mira variable period-age relation from Gaia
• Age-metallicity dependent stellar kinematics of the Milky Way disc from LAMOST and Gaia
• Identification, mass and age of primary red clump stars from spectral features derived with the LAMOST DR7
• Precise Masses, Ages of ~1.0 million RGB and RC stars observed by the LAMOST
• Evidence for Populations-dependent vertical motions and the Long-lived Non-Steady Lopsided Milky Way Warp
• A Combined Chandra and LAMOST Study of Stellar Activity
• Disk flaring with TNG50: diversity across Milky Way and M31 analogs
• A Crystallizing White Dwarf in a Sirius-Like Quadruple System
• The breakdown of current gyrochronology as evidenced by old coeval stars
• Mass and Age determination of the LAMOST data with different Machine Learning methods
• Rediscovering the Milky Way with orbit superposition approach and APOGEE data II. Chrono-chemo-kinematics of the disc
• Element abundance analysis of the metal-rich stellar halo and high-velocitythick disk in the galaxy
• Nearly 30,000 late-type main-sequence stars with stellar age from LAMOST DR5
• A Cool Earth-sized Planet Candidate Transiting a Tenth Magnitude K-dwarf From K2
• 3D elemental abundances of stars at formation across the histories of Milky Way-mass galaxies in the FIRE simulations
• Spatially Dependent Photometric Activity of M dwarfs in the Solar Cylinder
• Two sequences in the age-metallicity relation as seen from [C/N] abundances in APOGEE
• A 'Quick Look' at All-Sky Galactic Archeology with TESS: 158,000 Oscillating Red Giants from the MIT Quick-Look Pipeline