Chemical Evolution in the Milky Way: Rotation-based ages for APOGEE-Kepler cool dwarf stars

Abstract

We use models of stellar angular momentum evolution to determine ages for $\sim 500$ stars in the APOGEE-\textit{Kepler} Cool Dwarfs sample. We focus on lower main-sequence stars, where other age-dating tools become ineffective. Our age distributions are compared to those derived from asteroseismic and giant samples and solar analogs. We are able to recover gyrochronological ages for old, lower-main-sequence stars, a remarkable improvement over prior work in hotter stars. Under our model assumptions, our ages have a median relative uncertainty of $14\%$, comparable to the age precision inferred for more massive stars using traditional methods. We investigate trends of galactic $\alpha$-enhancement with age, finding evidence of a detection threshold between the age of the oldest $\alpha$-poor stars and that of the bulk $\alpha$-rich population. We argue that gyrochronology is an effective tool reaching ages of 10--12 Gyr in K- and early M-dwarfs. Finally, we present the first effort to quantify the impact of detailed abundance patterns on rotational evolution. We estimate a $\sim 15\%$ bias in age for cool, $\alpha$-enhanced (+ 0.4 dex) stars when standard solar-abundance-pattern rotational models are used for age inference, rather than models that appropriately account for $\alpha$-enrichment.

22 pages, 11 figures, 3 tables. Submitted to AAS Journals. Electronic version of Table 3 is available as ancillary file (sidebar on the right). For a brief video explaining this paper, see https://youtu.be/z5qQLUZzFDc. The code developed to interact with, interpolate, and sample the stellar models is publicly available at https://github.com/zclaytor/kiauhoku/

References in corpus (24)

• The Transiting Exoplanet Survey Satellite
• Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics
• The Mass-Dependence of Angular Momentum Evolution in Sun-Like Stars
• emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMC
• A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
• YREC: The Yale Rotating Stellar Evolution Code
• Improved angular momentum evolution model for solar-like stars II. Exploring the mass dependence
• Calibrating Gyrochronology using Kepler Asteroseismic targets
• Young [$\alpha$/Fe]-enhanced stars discovered by CoRoT and APOGEE: What is their origin?
• Accretion-Powered Stellar Winds II: Numerical Solutions for Stellar Wind Torques
• Testing the recovery of stellar rotation signals from Kepler light curves using a blind hare-and-hounds exercise
• A Temporary Epoch of Stalled Spin-Down for Low-Mass Stars: Insights from NGC 6811 with Gaia and Kepler
• Abundance to age ratios in the HARPS-GTO sample with Gaia DR2: Chemical clocks for a range of [Fe/H]
• The First APOKASC Catalog of Kepler Dwarf and Subgiant Stars
• Impact on asteroseismic analyses of regular gaps in Kepler data
• Gap interpolation by inpainting methods : Application to Ground and Space-based Asteroseismic data
• Surface rotation of Kepler red giant stars
• Deep MMT Transit Survey of the Open Cluster M37 III: Stellar Rotation at 550 Myr
• The influence of metallicity on stellar differential rotation and magnetic activity
• On the metallicity dependance of the [Y/Mg] - age relation for solar type stars
• The Asteroseismic Target List (ATL) for solar-like oscillators observed in 2-minute cadence with the Transiting Exoplanet Survey Satellite (TESS)
• Rapid Rotation of Low-Mass Red Giants Using APOKASC: A Measure of Interaction Rates on the Post-main-sequence
• OPserver: interactive online-computations of opacities and radiative accelerations
• A Search for Red Giant Solar-like Oscillations in All Kepler Data

Cited by in corpus (29)

• Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs
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• Gyro-Kinematic Ages for around 30,000 Kepler Stars
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• Rotation Distributions around the Kraft Break with TESS and Kepler: The Influences of Age, Metallicity, and Binarity
• The TIME Table: Rotation and Ages of Cool Exoplanet Host Stars
• The Evolution of Rotation and Magnetic Activity in 94 Aqr Aa from Asteroseismology with TESS
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• Magnetic activity evolution of solar-like stars: I. S_ph-Age relation derived from Kepler observations
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• TKS V. Twin sub-Neptunes Transiting the Nearby G Star HD 63935
• The influence of planetary engulfment on stellar rotation in metal-poor main-sequence stars
• Rotation at the Fully Convective Boundary: Insights from Wide WD + MS Binary Systems
• Kepler main-sequence solar-like stars: surface rotation and magnetic-activity evolution
• Is [Y/Mg] a Reliable Age Diagnostic for FGK Stars?
• A Framework for Relative Biosignature Yields from Future Direct Imaging Missions
• The Abundance of Belatedly Habitable Planets and Ambiguities in Definitions of the Continuously Habitable Zone
• fBLS -- a fast-folding BLS algorithm
• ChronoFlow: A Data-Driven Model for Gyrochronology
• MAISTEP -- a new grid-based machine learning tool for inferring stellar parameters I. Ages of giant-planet host stars
• Exoplanet Occurrence Rate with Age for FGK Stars in Kepler
• The 3D Galactocentric velocities of Kepler stars: marginalizing over missing RVs
• Asteroseismically Inferred Ages of 132,000 Red Giants with TESS
• Abundant sub-micron grains revealed in newly discovered extreme debris discs
• A Pair of Dynamically Interacting Sub-Neptunes Around TOI-6054
• Potential Habitability as a Stellar Property: Effects of Model Uncertainties and Measurement Precision