Ages and Masses of 0.64 million Red Giant Branch stars from the LAMOST Galactic Spectroscopic Survey

Abstract

We present a catalog of stellar age and mass estimates for a sample of 640\,986 red giant branch (RGB) stars of the Galactic disk from the LAMOST Galactic Spectroscopic Survey (DR4). The RGB stars are distinguished from the red clump stars utilizing period spacing derived from the spectra with a machine learning method based on kernel principal component analysis (KPCA). Cross-validation suggests our method is capable of distinguishing RC from RGB stars with only 2 per cent contamination rate for stars with signal-to-noise ratio (SNR) higher than 50. The age and mass of these RGB stars are determined from their LAMOST spectra with KPCA method by taking the LAMOST - $Kepler$ giant stars having asteroseismic parameters and the LAMOST-TGAS sub-giant stars based on isochrones as training sets. Examinations suggest that the age and mass estimates of our RGB sample stars with SNR $>$ 30 have a median error of 30 per cent and 10 per cent, respectively. Stellar ages are found to exhibit positive vertical and negative radial gradients across the disk, and the age structure of the disk is strongly flared across the whole disk of $6<R<13$\,kpc. The data set demonstrates good correlations among stellar age, [Fe/H] and [$\alpha$/Fe]. There are two separate sequences in the [Fe/H] -- [$\alpha$/Fe] plane: a high--$\alpha$ sequence with stars older than $\sim$\,8\,Gyr and a low--$\alpha$ sequence composed of stars with ages covering the whole range of possible ages of stars. We also examine relations between age and kinematic parameters derived from the Gaia DR2 parallax and proper motions. Both the median value and dispersion of the orbital eccentricity are found to increase with age. The vertical angular momentum is found to fairly smoothly decrease with age from 2 to 12\,Gyr, with a rate of about $-$50\,kpc\,km\,s${}^{-1}$\,Gyr${}^{-1}$. A full table of the catalog is public available online.

arXiv comment16 pages, 22 figures,accepted by MNRAS

References in corpus (68)

• Planck 2015 results. XIII. Cosmological parameters
• The Gaia mission
• The Fourth US Naval Observatory CCD Astrograph Catalog (UCAC4)
• Radial Mixing in Galactic Discs
• The GALAH Survey: Scientific Motivation
• Chemical evolution with radial mixing
• Gaia Data Release 2: Kinematics of globular clusters and dwarf galaxies around the Milky Way
• Chemical Cartography with APOGEE: Metallicity Distribution Functions and the Chemical Structure of the Milky Way Disk
• Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars
• The Ages of Stars
• The age structure of stellar populations in the solar vicinity. Clues of a two-phase formation history of the Milky Way disk
• Asteroseismology of Solar-Type and Red-Giant Stars
• Riding the Spiral Waves: Implications of Stellar Migration for the Properties of Galactic Disks
• Asteroseismic fundamental properties of solar-type stars observed by the NASA Kepler Mission
• The APOKASC Catalog: An Asteroseismic and Spectroscopic Joint Survey of Targets in the Kepler Fields
• A consistent explanation for ${}^{12}$C/${}^{13}$C, ${}^7$Li, and ${}^3$He anomalies in red giant stars
• Old stellar Galactic disc in near-plane regions according to 2MASS: scales, cut-off, flare and warp
• Red giant masses and ages derived from carbon and nitrogen abundances
• Probing the core structure and evolution of red giants using gravity-dominated mixed modes observed with Kepler
• Asteroseismic classification of stellar populations among 13000 red giants observed by Kepler
• The Genesis of the Milky Way's Thick Disk via Stellar Migration
• Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane
• Asteroseismology of 16000 Kepler Red Giants: Global Oscillation Parameters, Masses, and Radii
• The APOGEE red-clump catalog: Precise distances, velocities, and high-resolution elemental abundances over a large area of the Milky Way's disk
• Mixed modes in red giants: a window on stellar evolution
• Formation and Evolution of the Disk System of the Milky Way: [alpha/Fe] Ratios and Kinematics of the SEGUE G-Dwarf Sample
• Spectroscopic determination of masses (and implied ages) for red giants
• Stellar population synthesis based modelling of the Milky Way using asteroseismology of 13000 Kepler red giants
• Deep Wide-Field Spectrophotometry of the Open Cluster M67
• The Milky Way's rotation curve out to 100 kpc and its constraint on the Galactic mass distribution
• The age of the oldest Open Clusters
• Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?
• On the Formation of Galactic Thick Disks
• Mixed modes in red-giant stars observed with CoRoT
• Period spacings in red giants II. Automated measurement
• The LAMOST Stellar Parameter Pipeline at Peking University --- LSP3
• Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)
• Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA
• LAMOST observations in the Kepler field. Database of low-resolution spectra
• Isochrone ages for ~3 million stars with the second Gaia data release
• LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC): target selection and the first release of value-added catalogues
• Rotation periods for cool stars in the 4 Gyr-old open cluster M67, the solar-stellar connection, and the applicability of gyrochronology to at least solar age
• Estimating stellar atmospheric parameters, absolute magnitudes and elemental abundances from the LAMOST spectra with Kernel-based Principal Component Analysis
• Deep 2MASS Photometry of M67 and Calibration of the Main Sequence J-Ks Color Difference as an Age Indicator
• Imprints of radial migration on the Milky Way's metallicity distribution functions
• Seismic diagnostics of red giants: first comparison with stellar models
• The White Dwarf Cooling Age of M67
• Flare in the Galactic stellar outer disc detected in SDSS-SEGUE data
• Ages and masses of million Galactic disk main sequence turn-off and sub-giant stars from the LAMOST Galactic spectroscopic surveys
• Deep Mixing and Metallicity: Carbon Depletion in Globular Cluster Giants
• LAMOST observations in the Kepler field. II. Database of the low-resolution spectra from the five-year regular survey
• A large and pristine sample of standard candles across the Milky Way: ~100,000 red clump stars with 3% contamination
• A New Method for the Asteroseismic Determination of the Evolutionary State of Red-Giant Stars
• Abundance gradients along the Galactic disc from chemical evolution models
• Masses and Ages for 230,000 LAMOST Giants, via Their Carbon and Nitrogen Abundances
• A Unified tool to estimate Distances, Ages and Masses (UniDAM) from spectrophotometric data
• Stellar mass distribution and star formation history of the Galactic disk revealed by mono-age stellar populations from LAMOST
• On the Fate of Unstable Circumbinary Planets: Tatooine's Close Encounters with a Death Star
• Mass and Age of Red Giant Branch Stars Observed with LAMOST and \emph{Kepler}
• Probing the Galaxy's bars via the Hercules stream
• Zeroing the Stellar Isochrone Scale: The Red Giant Clump Luminosity at Intermediate Metallicity
• LAMOST observations in the Kepler field. Analysis of the stellar parameters measured with the LASP based on the low-resolution spectra
• Nitrogen depletion in field red giants: mixing during the He flash?
• Fluorine in the Solar Neighborhood: Chemical Evolution Models
• The old open clusters Berkeley 32 and King 11
• Photospheric diagnostics of core helium burning in giant stars
• Tomographic Intensity Mapping versus Galaxy Surveys: Observing the Universe in H-alpha emission with new generation instruments
• The old anticentre open cluster Berkeley 32: membership and fundamental parameters

Cited by in corpus (38)

• Chemical Enrichment and Radial Migration in the Galactic Disk -- the origin of the [$\alpha /\mathrm{Fe}]$ Double Sequence
• Overview of the LAMOST survey in the first decade
• Fundamental relations for the velocity dispersion of stars in the Milky Way
• VINTERGATAN II: the history of the Milky Way told by its mergers
• A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
• Spectroscopic age estimates for APOGEE red-giant stars: Precise spatial and kinematic trends with age in the Galactic disc
• The age-chemical abundance structure of the Galactic disc II: $\alpha$-dichotomy and thick disc formation
• 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
• Characterizing epochs of star formation across the Milky Way disc using age-metallicity distributions of GALAH stars
• Age-chemical abundance structure of the Galaxy I: Evidence for a late accretion event in the outer disc at z ~ 0.6
• Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
• Quantifying radial migration in the Milky Way: Inefficient over short timescales but essential to the very outer disc beyond ~15 kpc
• Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. II. 3D asymmetrical kinematics of mono-age populations in the disk between 6$-14$ \,kpc
• Overview of the LAMOST-$Kepler$ project
• Radial structure and formation of the Milky Way disc
• Most "young" $\alpha$-rich stars have high masses but are actually old
• Milky Way Analogues in MaNGA: Multi-Parameter Homogeneity and Comparison to the Milky Way
• Are the Milky Way and Andromeda unusual? A comparison with Milky Way and Andromeda Analogs
• Testing Self-Organized Criticality Across the Main Sequence using Stellar Flares from TESS
• Correction to the photometric colors of the Gaia Data Release 2 with the stellar color regression method
• Star Formation Timescales of the Halo Populations from Asteroseismology and Chemical Abundances
• Origin of metals in old Milky Way halo stars based on GALAH and 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
• From the Inner to Outer Milky Way: A Photometric Sample of 2.6 Million Red Clump Stars
• Li-rich Giants in LAMOST Survey. III. The statistical analysis of Li-rich giants
• Influence of the Galactic bar on the kinematics of the disc stars with Gaia EDR3 data
• Mass and Age determination of the LAMOST data with different Machine Learning methods
• Modelling stars with Gaussian Process Regression: Augmenting Stellar Model Grid
• Existence of the Metal-Rich Stellar Halo and High-velocity Thick Disk in the Galaxy
• Dormant black hole candidates from Gaia DR3 summary diagnostics
• Ba-enhanced dwarf and subgiant stars in the LAMOST Galactic surveys
• LTD064402+245919: A Subgiant with a 1-3 M${}_{\odot }$ Undetected Companion Identified from LAMOST-TD Data
• Weighing stars from birth to death: mass determination methods across the HRD
• Kinematic-Chemical analysis and Time tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red Giant Branch Stars
• Nearly 30,000 late-type main-sequence stars with stellar age from LAMOST DR5
• Exploring the History of Stellar Mergers with Chemistry: Examining the Origins of Massive $\alpha$-Enriched Stars using Carbon Isotope Ratios