The APO-K2 Catalog. II. Accurate Stellar Ages for Red Giant Branch Stars across the Milky Way

Abstract

We present stellar age determinations for 4661 red giant branch stars in the APO-K2 catalog, derived using mass estimates from K2 asteroseismology from the K2 Galactic Archaeology Program and elemental abundances from the Apache Point Galactic Evolution Experiment survey. Our sample includes 17 of the 19 fields observed by K2, making it one of the most comprehensive catalogs of accurate stellar ages across the Galaxy in terms of the wide range of populations spanned by its stars, enabling rigorous tests of Galactic chemical evolution models. Taking into account the selection functions of the K2 sample, the data appear to support the age-chemistry morphology of stellar populations predicted by both inside-out and late-burst scenarios. We also investigate trends in age versus stellar chemistry and Galactic position, which are consistent with previous findings. Comparisons against APOKASC-3 asteroseismic ages show agreement to within ~3%. We also discuss offsets between our ages and spectroscopic ages. Finally, we note that ignoring the effects of $\alpha$-enhancement on stellar opacity (either directly or with the Salaris metallicity correction) results in an ~10% offset in age estimates for the most $\alpha$-enhanced stars, which is an important consideration for continued tests of Galactic models with this and other asteroseismic age samples.

References in corpus (91)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• The Gaia mission
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• Gaia Data Release 3: Summary of the content and survey properties
• The Transiting Exoplanet Survey Satellite
• The 2.5 m Telescope of the Sloan Digital Sky Survey
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The K2 Mission: Characterization and Early results
• Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe
• Accurate masses and radii of normal stars: modern results and applications
• Radial Mixing in Galactic Discs
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• The Chemical Evolution of the Galaxy: the two-infall model
• Galactic Chemical Evolution: Hydrogen Through Zinc
• The GALAH Survey: Scientific Motivation
• Chemical evolution with radial mixing
• 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 age structure of stellar populations in the solar vicinity. Clues of a two-phase formation history of the Milky Way disk
• Estimating distances from parallaxes
• APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South
• The Data Reduction Pipeline for the Apache Point Observatory Galactic Evolution Experiment
• The Galactic Thick Disk Stellar Abundances
• Abundances, Stellar Parameters, and Spectra From the SDSS-III/APOGEE Survey
• Rates and Delay Times of Type Ia Supernovae
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE) Spectrographs
• Galaxia: a code to generate a synthetic survey of the Milky Way
• The Second APOKASC Catalog: The Empirical Approach
• Calculating asteroseismic diagrams for solar-like oscillations
• The Milky Way has no thick disk
• APOGEE Data Releases 13 and 14: Data and Analysis
• Low-Metallicity Inhibition of Type Ia Supernovae and Galactic and Cosmic Chemical Evolution
• A Morphological Catalog of Galaxies in the Hubble Deep Field
• Red giant masses and ages derived from carbon and nitrogen abundances
• The APOGEE red-clump catalog: Precise distances, velocities, and high-resolution elemental abundances over a large area of the Milky Way's disk
• Dynamical heating across the Milky Way disc using APOGEE and $Gaia$
• Faintest Galaxy Morphologies from $HST$ WFPC2 Imaging of the Hawaii Survey Fields
• Stellar population synthesis based modelling of the Milky Way using asteroseismology of 13000 Kepler red giants
• Deep learning of multi-element abundances from high-resolution spectroscopic data
• Galactic Archaeology with asteroseismic ages: evidence for delayed gas infall in the formation of the Milky Way disc
• Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?
• Age dissection of the Milky Way discs: red giants in the Kepler field
• The Long-term Evolution of the Galactic Disk Traced by Dissolving Star Clusters
• Implementing Molecular Hydrogen in Hydrodynamic Simulations of Galaxy Formation
• Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)
• Distances and parallax bias in Gaia DR2
• Measuring the vertical age structure of the Galactic disc using asteroseismology and SAGA
• An update to the EVEREST K2 pipeline: Short cadence, saturated stars, and Kepler-like photometry down to Kp = 15
• The Correlation Between Mixing Length and Metallicity on the Giant Branch: Implications for Ages in the Gaia Era
• Gap interpolation by inpainting methods : Application to Ground and Space-based Asteroseismic data
• Equilibrium and Sudden Events in Chemical Evolution
• Gaia DR2 reveals a star formation burst in the disc 2-3 Gyr ago
• Chemical Enrichment and Radial Migration in the Galactic Disk -- the origin of the [$\alpha /\mathrm{Fe}]$ Double Sequence
• Oscillating red giants observed during Campaign 1 of the Kepler K2 mission: New prospects for galactic archaeology
• The imprint of clump formation at high redshift. I. A disc alpha-abundance dichotomy
• Testing the Asteroseismic Mass Scale Using Metal-Poor Stars Characterized with APOGEE and Kepler
• Galactic Archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE
• Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
• Period-luminosity relations in evolved red giants explained by solar-like oscillations
• The vertical motion history of disk stars throughout the Galaxy
• The K2 Galactic Archaeology Program Data Release 1: Asteroseismic results from Campaign 1
• Post first dredge-up [C/N] ratio as age indicator. Theoretical calibration
• Fundamental relations for the velocity dispersion of stars in the Milky Way
• Testing the radius scaling relation with $Gaia$ DR2 in the $Kepler$ field
• The K2-HERMES Survey: Age and Metallicity of the Thick Disc
• A Tale of Two Disks: Mapping the Milky Way with the Final Data Release of APOGEE
• Deep Learning Classification in Asteroseismology Using an Improved Neural Network: Results on 15000 Kepler Red Giants and Applications to K2 and TESS Data
• The Sensitivity of Convection Zone Depth to Stellar Abundances: An Absolute Stellar Abundance Scale from Asteroseismology
• Spectroscopic age estimates for APOGEE red-giant stars: Precise spatial and kinematic trends with age in the Galactic disc
• Unveiling the Distinct Formation Pathways of the Inner and Outer Discs of the Milky Way with Bayesian Machine Learning
• Near-infrared narrow-band photometry of M-giant and Mira stars: models meet observations
• The Aarhus Red Giants Challenge I: Stellar structures in the red giant branch phase
• Assessing distances and consistency of kinematics in Gaia/TGAS
• Detection and characterisation of oscillating red giants: first results from the TESS satellite
• MADE: A spectroscopic Mass, Age, and Distance Estimator for red giant stars with Bayesian machine learning
• The K2 Galactic Archaeology Program Data Release 3: Age-abundance patterns in C1-C8 and C10-C18
• The star formation history in the solar neighborhood as told by massive white dwarfs
• A variational encoder-decoder approach to precise spectroscopic age estimation for large Galactic surveys
• Insights from the APOKASC Determination of the Evolutionary State of Red-Giant Stars by consolidation of different methods
• The K2 Galactic Caps Project -- Going Beyond the \textit{Kepler} Field and Ageing the Galactic Disc
• The evolution of the Milky Way's thin disc radial metallicity gradient with K2 asteroseismic ages
• The K2 Galactic Archaeology Program Data Release 2: Asteroseismic results from campaigns 4, 6, & 7
• Nature vs. Nurture: Distinguishing Effects from Stellar Processing and Chemical Evolution on Carbon and Nitrogen in Red Giant Stars
• An Intermediate-age Alpha-rich Galactic Population in K2
• Comparison of the Asteroseismic Mass Scale of Red Clump Giants with Photometric Mass Estimates
• Disc dichotomy signature in the vertical distribution of [Mg/Fe] and the delayed gas infall scenario
• A Unified Exploration of the Chronology of the Galaxy
• The K2 Galactic Archaeology Program: Overview, target selection and survey properties

Cited by in corpus (5)

• Red giants evolutionary status determination: the complete Kepler catalog
• Deciphering the Milky Way disc formation time encrypted in the bar chrono-kinematics
• StarFlow: Leveraging Normalizing Flows for Stellar Age Estimation in SDSS-V DR19
• GaiaUnlimited: The old stellar disc of the Milky Way as traced by the Red Clump
• Th/Eu abundance ratio of red giants in the Kepler Field