The evolution of the Milky Way's thin disc radial metallicity gradient with K2 asteroseismic ages

Abstract

The radial metallicity distribution of the Milky Way's disc is an important observational constraint for models of the formation and evolution of our Galaxy. It informs our understanding of the chemical enrichment of the Galactic disc and the dynamical processes therein, particularly radial migration. We investigate how the metallicity changes with guiding radius in the thin disc using a sample of red-giant stars with robust astrometric, spectroscopic and asteroseismic parameters. Our sample contains $668$ stars with guiding radii $4$ kpc < $R_{\mathrm{g}}$ < $11$ kpc and asteroseismic ages covering the whole history of the thin disc with precision $\approx 25\%$. We use MCMC analysis to measure the gradient and its intrinsic spread in bins of age and construct a hierarchical Bayesian model to investigate the evolution of these parameters independently of the bins. We find a smooth evolution of the gradient from $\approx -0.07$ dex/kpc in the youngest stars to $\approx -0.04$ dex/kpc in stars older than $10$ Gyr, with no break at intermediate ages. Our results are consistent with those based on asteroseismic ages from CoRoT, with that found in Cepheid variables for stars younger than $1$ Gyr, and with open clusters for stars younger than $6$ Gyr. For older stars we find a significantly lower metallicity in our sample than in the clusters, suggesting a survival bias favouring more metal-rich clusters. We also find that the chemical evolution model of Chiappini (2009) is too metal-poor in the early stages of disc formation. Our results provide strong new constraints for the growth and enrichment of the thin disc and radial migration, which will facilitate new tests of model conditions and physics.

arXiv comment15 pages, 16 figures. Accepted for publication in MNRAS

References in corpus (80)

• SciPy 1.0--Fundamental Algorithms for Scientific Computing in Python
• Array Programming with NumPy
• Astropy: A Community Python Package for Astronomy
• emcee: The MCMC Hammer
• 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
• Local Kinematics and the Local Standard of Rest
• The No-U-Turn Sampler: Adaptively Setting Path Lengths in Hamiltonian Monte Carlo
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• The K2 Mission: Characterization and Early results
• The Geneva-Copenhagen survey of the Solar neighbourhood: Ages, metallicities, and kinematic properties of 14,000 F and G dwarfs
• galpy: A Python Library for Galactic Dynamics
• The PLATO 2.0 Mission
• Radial Mixing in Galactic Discs
• The Chemical Evolution of the Galaxy: the two-infall model
• New constraints on the chemical evolution of the solar neighbourhood and Galactic disc(s). Improved astrophysical parameters for the Geneva-Copenhagen Survey
• ASPCAP: The Apogee Stellar Parameter and Chemical Abundances Pipeline
• Chemical evolution with radial mixing
• The GALAH+ Survey: Third Data Release
• The Ages of Stars
• LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan
• Asteroseismology of Solar-Type and Red-Giant Stars
• Basic physical parameters of a selected sample of evolved stars
• Kepler Asteroseismology Program: Introduction and First Results
• Chemodynamical evolution of the Milky Way disk I: The solar vicinity
• Vertical waves in the solar neighbourhood in Gaia DR2
• The Milky Way's circular velocity curve between 4 and 14 kpc from APOGEE data
• Origin and structure of the Galactic disc(s)
• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• Gas accretion as the origin of chemical abundance gradients in distant galaxies
• Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane
• Composable Effects for Flexible and Accelerated Probabilistic Programming in NumPyro
• Radial mixing and the transition between the thick and thin Galactic discs
• On detecting the large separation in the autocorrelation of stellar oscillation times series
• Chemodynamics of the Milky Way. I. The first year of APOGEE data
• From dawn till disk: Milky Way's turbulent youth revealed by the APOGEE+Gaia data
• Galactic Metallicity Gradients Derived from a Sample of OB Stars
• Data analysis recipes: Fitting a model to data
• HII Region Metallicity Distribution in the Milky Way Disk
• On the fine structure of the Cepheid metallicity gradient in the Galactic thin disk
• Estimating stellar birth radii and the time evolution of the Milky Way's ISM metallicity gradient
• Bayesian distances and extinctions for giants observed by Kepler and APOGEE
• The evolution of the Galactic metallicity gradient from high-resolution spectroscopy of open clusters
• Age dissection of the Milky Way discs: red giants in the Kepler field
• The Gaia-ESO Public Spectroscopic Survey: Implementation, data products, open cluster survey, science, and legacy
• Evolution of the Milky Way with radial motions of stars and gas I. The solar neighborhood and the thin and thick disk
• Chemical Cartography with APOGEE: Large-scale Mean Metallicity Maps of the Milky Way
• The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- II: Stellar Atmospheric Parameters, Chemical Abundances and Distances
• The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- I: Survey Description, Spectra and Radial Velocities
• Measuring Radial Orbit Migration in the Milky Way Disk
• Carbon and Oxygen Galactic Gradients: Observational Values from HII Region Recombination Lines
• Red giants observed by CoRoT and APOGEE: The evolution of the Milky Way's radial metallicity gradient
• Chronologically dating the early assembly of the Milky Way
• Determining stellar parameters of asteroseismic targets: going beyond the use of scaling relations
• The GALAH survey: tracing the Galactic disk with Open Clusters
• The AMBRE Project: chemical evolution models for the Milky Way thick and thin discs
• The Inside-out Growth of the Galactic Disk
• Galactic Archaeology with asteroseismology and spectroscopy: Red giants observed by CoRoT and APOGEE
• PLATO as it is: a legacy mission for Galactic archaeology
• Keeping it Cool: Much Orbit Migration, yet Little Heating, in the Galactic Disk
• APOGEE DR16: a multi-zone chemical evolution model for the Galactic disc based on MCMC methods
• The vertical motion history of disk stars throughout the Galaxy
• Fast estimation of orbital parameters in Milky-Way-like potentials
• Impact of radial migration on stellar and gas radial metallicity distribution
• Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
• Evolution of the Milky Way with radial motions of stars and gas II. The evolution of abundance profiles from H to Ni
• The Open Cluster Chemical Abundances and Mapping Survey: VI. Galactic Chemical Gradient Analysis from APOGEE DR17
• Mapping the Galactic Metallicity Gradient with Open Clusters: The State-of-the-Art and Future Challenges
• Abundance gradients along the Galactic disc from chemical evolution models
• The Galactic metallicity gradient shown by open clusters in the light of radial migration
• Metallicity gradients in Local Universe galaxies: time evolution and effects of radial migration
• OCCASO III. Iron peak and $\alpha$ elements of 18 open clusters. Comparison with chemical evolution models and field stars
• Prospects for Galactic and stellar astrophysics with asteroseismology of giant stars in the $TESS$ Continuous Viewing Zones and beyond
• OCCASO II. Physical parameters and Fe abundances of Red Clump stars in 18 Open Clusters
• Radial abundance gradients in the outer Galactic disk as traced by main-sequence OB stars
• How accurate are stellar ages based on stellar models? II. The impact of asteroseismology
• Metallicity distributions of mono-age stellar populations of the Galactic disc from the LAMOST Galactic spectroscopic surveys
• Constraining the Milky Way assembly history with Galactic Archaeology. Ludwig Biermann Award Lecture 2015
• Milky Way chemo-dynamics in the era of Gaia

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• Mapping radial abundance gradients with Gaia-ESO open clusters: Evidence of recent gas accretion in the Milky Way disk
• The APO-K2 Catalog. II. Accurate Stellar Ages for Red Giant Branch Stars across the Milky Way
• Rediscovering the Milky Way with orbit superposition approach and APOGEE data II. Chrono-chemo-kinematics of the disc
• Metallicities of old open clusters: A new Galactic map
• Probing the origins. I. Generalised Additive Model inference of birth radii for Milky Way stars in the solar vicinity
• On the Use of Field RR Lyrae as Galactic Probes -- VIII. Early Formation of the Galactic Spheroid
• Revisiting the Radial Metallicity Gradient-Age Relation in the Milky Way's Thin and Thick Disks
• A comparative study of O, Ne, Cl, and Ar in Hii regions and PNe of the Galactic disk: Temporal evolution of radial gradients?