Rotation at the Fully Convective Boundary: Insights from Wide WD + MS Binary Systems

Abstract

Gyrochronology, a valuable tool for determining ages of low-mass stars where other techniques fail, relies on accurate calibration. We present a sample of 185 wide ($>$$100$ au) white dwarf + main sequence (WD + MS) binaries. Total ages of WDs are computed using all-sky survey photometry, Gaia parallaxes, and WD atmosphere models. Using a magnetic braking law calibrated against open clusters, along with assumptions about initial conditions and angular momentum transport, we construct gyrochrones to predict the rotation periods of MS stars. Both data and models show that, at the fully convective boundary (FCB), MS stars with WD ages up to 7.5 Gyr and within a $<50$ K effective temperature range experience up to a threefold increase in rotation period relative to stars slightly cooler than the FCB. We suggest that rapid braking at this boundary is driven by a sharp rise in the convective overturn timescale (${\tau }_{\mathrm{cz}}$) caused by structural changes between partially and fully convective stars and the ${}^3\text{He}$ instability occurring at this boundary. While the specific location in mass (or temperature) of this feature varies with model physics, we argue that its existence remains consistent. Stars along this feature exhibit rotation periods that can be mapped, within 1$\sigma$, to a range of gyrochrones spanning $\approx 6$ Gyr. Due to current temperature errors ($\simeq$$50$ K), this implies that a measured rotation period cannot be uniquely associated to a single gyrochrone, implying that gyrochronology may not be feasible for M dwarfs very close to the FCB.

Accepted to ApJ. 31 pages, 20 figures, 3 tables

References in corpus (112)

• emcee: The MCMC Hammer
• Galactic Stellar and Substellar Initial Mass Function
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• Modules for Experiments in Stellar Astrophysics (MESA): Binaries, Pulsations, and Explosions
• The Man Behind the Curtain: X-rays Drive the UV through NIR Variability in the 2013 AGN Outburst in NGC 2617
• Low Temperature Opacities
• Protoplanetary Disks and Their Evolution
• The Second Data Release of the Sloan Digital Sky Survey
• The stellar activity-rotation relationship and the evolution of stellar dynamos
• Solar Models with Helium and Heavy Element Diffusion
• Ages for illustrative field stars using gyrochronology: viability, limitations and errors
• Gaia Early Data Release 3: Photometric content and validation
• Solar fusion cross sections II: the pp chain and CNO cycles
• Rotation Periods of 34,030 Kepler Main-Sequence Stars: The Full Autocorrelation Sample
• How to Constrain Your M Dwarf: measuring effective temperature, bolometric luminosity, mass, and radius
• Element Diffusion in the Solar Interior
• The Ages of Stars
• Observational Constraints on the Formation and Evolution of Binary Stars
• Measuring the rotation period distribution of field M-dwarfs with Kepler
• The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey
• A million binaries from Gaia eDR3: sample selection and validation of Gaia parallax uncertainties
• The ASAS-SN Catalog of Variable Stars I: The Serendipitous Survey
• A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• Weakened magnetic braking as the origin of anomalously rapid rotation in old field stars
• SDSS DR7 White Dwarf Catalog
• The GALAH Survey: Second Data Release
• The H$\alpha$ emission of nearby M dwarfs and its relation to stellar rotation
• A First Catalog of Variable Stars Measured by the Asteroid Terrestrial-impact Last Alert System (ATLAS)
• Large-scale magnetic topologies of early M dwarfs
• A catalogue of white dwarfs in Gaia EDR3
• The White Dwarf Initial-Final Mass Relation for Progenitor Stars From 0.85 to 7.5 M${}_{\odot }$
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• The Zwicky Transient Facility Catalog of Periodic Variable Stars
• Stellar Lyman-alpha Emission Lines in the Hubble Space Telescope Archive: Intrinsic Line Fluxes and Absorption from the Heliosphere and Astrospheres
• The stellar rotation--activity relationship in fully convective M dwarfs
• A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
• New white dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 12
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10
• Gaia Data Release 3: Analysis of RVS spectra using the General Stellar Parametriser from spectroscopy
• The Kepler Cluster Study: Stellar Rotation in NGC6811
• Magnetic Braking Formulation for Sun-Like Stars: Dependence on Dipole Field Strength and Rotation Rate
• A white dwarf cooling age of 8 Gyr for NGC 6791 from physical separation processes
• Know Your Neighborhood: A Detailed Model Atmosphere Analysis of Nearby White Dwarfs
• Rotation in the Pleiades with K2: I. Data and First Results
• Fast Star, Slow Star; Old Star, Young Star: Subgiant Rotation as a Population and Stellar Physics Diagnostic
• Updated Gaia-2MASS 3D maps of Galactic interstellar dust
• Angular Momentum Loss from Cool Stars: An Empirical Expression and Connection to Stellar Activity
• Detached white dwarf main-sequence star binaries
• On the Measurement of Fundamental Parameters of White Dwarfs in the Gaia Era
• Confirming chemical clocks: asteroseismic age dissection of the Milky Way disk(s)
• When Do Stalled Stars Resume Spinning Down? Advancing Gyrochronology with Ruprecht 147
• How Good a Clock is Rotation? The Stellar Rotation-Mass-Age Relationship for Old Field Stars
• Rotation of Low-Mass Stars in Upper Scorpius and Rho Ophiuchus with K2
• K2 rotation periods for low-mass Hyads and a quantitative comparison of the distribution of slow rotators in the Hyades and Praesepe
• Where are the most ancient stars in the Milky Way?
• First grids of low-mass stellar models and isochrones with self-consistent treatment of rotation : From 0.2 to 1.5 M_\odot at 7 metallicities from PMS to TAMS
• Predicting the detectability of oscillations in solar-type stars observed by Kepler
• A Temporary Epoch of Stalled Spin-Down for Low-Mass Stars: Insights from NGC 6811 with Gaia and Kepler
• Surface rotation and photometric activity for Kepler targets I. M and K main-sequence stars
• Analysis of Helium-Rich White Dwarfs Polluted by Heavy Elements in the Gaia Era
• Angular Momentum Transport In Solar-Type Stars: Testing the Timescale For Core-Envelope Coupling
• Poking the Beehive From Space: K2 Rotation Periods For Praesepe
• On the magnetic topology of partially and fully convective stars
• An Age Difference of 2 Gyr between a Metal-Rich and a Metal-Poor Globular Cluster
• Older and Colder: The impact of starspots on pre-main sequence stellar evolution
• On the competing effect of wind braking and interior coupling in the rotational evolution of solar-like stars
• The SPOTS Models: A Grid of Theoretical Stellar Evolution Tracks and Isochrones For Testing The Effects of Starspots on Structure and Colors
• New rotation period measurements for M dwarfs in the southern hemisphere: an abundance of slowly rotating, fully convective stars
• CARMENES input catalogue of M dwarfs IV. New rotation periods from photometric time series
• Stellar rotation periods from K2 Campaigns 0-18 -- Evidence for rotation period bimodality and simultaneous variability decrease
• Variability Properties of 4 Million Sources in the $TESS$ Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey
• Weakened magnetic braking supported by asteroseismic rotation rates of Kepler dwarfs
• Forward Modeling of the Kepler Stellar Rotation Period Distribution: Interpreting Periods from Mixed and Biased Stellar Populations
• Looks can be deceiving: underestimating the age of single white dwarfs due to binary mergers
• Far-Ultraviolet Activity Levels of F, G, K, and M dwarf Exoplanet Host Stars
• Where are all the Sirius-Like Binary Systems?
• A Gap in the Lower Main Sequence Revealed by Gaia Data Release 2
• The Physics of Crystallization from Globular Cluster White Dwarf Stars in NGC 6397
• The Impact of Metallicity on the Evolution of Rotation and Magnetic Activity of Sun-Like Stars
• Rotational evolution of slow-rotators sequence stars
• The Sensitivity of Convection Zone Depth to Stellar Abundances: An Absolute Stellar Abundance Scale from Asteroseismology
• Chemical Evolution in the Milky Way: Rotation-based ages for APOGEE-Kepler cool dwarf stars
• The Effects of Close Companions (and Rotation) on the Magnetic Activity of M Dwarfs
• Properties of Carbon-Oxygen White Dwarfs From Monte Carlo Stellar Models
• Rapid Rotation in the Kepler Field: Not a Single Star Phenomenon
• A 4 Gyr M-dwarf Gyrochrone from CFHT/MegaPrime Monitoring of the Open Cluster M67
• The white dwarf luminosity function
• A Spectro-photometric Analysis of Cool White Dwarfs in the Gaia and Pan-STARRS Footprint
• Two Massive White Dwarfs from NGC 2323 and the Initial-Final Mass Relation for Progenitors of 4 to 6.5 M${}_{\odot }$
• A He3 driven instability near the fully convective boundary
• The Chromospheric Activity, Age, Metallicty and Space Motions of 36 Wide Binaries
• Lithium depletion is a strong test of core-envelope recoupling
• Gyro-Kinematic Ages for around 30,000 Kepler Stars
• Spectrophotometric analysis of magnetic white dwarf I: Hydrogen-rich compositions
• Starspots and Magnetism: Testing the Activity Paradigm in the Pleiades and M67
• 3D spectroscopic analysis of helium-line white dwarfs
• M dwarf companions to white dwarfs I: relating magnetic activity, rotation and age
• Bridging the gap -- the disappearance of the intermediate period gap for fully convective stars, uncovered by new ZTF rotation periods
• Constraining the solar neighbourhood age-metallicity relation from white dwarf-main sequence binaries
• Stellar population astrophysics (SPA) with the TNG. Revisiting the metallicity of Praesepe (M44)
• The White Dwarf Age of NGC 2477
• Gaia Gaps and the Physics of Low-Mass Stars. I. The Fully Convective Boundary
• The age-metallicity relation in the solar neighbourhood from a pilot sample of white dwarf-main sequence binaries
• M Dwarf rotation from the $K2$ young clusters to the field. I. A Mass-Rotation Correlation at 10 Myr
• Kinematic properties of white dwarfs. Galactic orbital parameters and age-velocity dispersion relation
• A Novel Approach to Constrain Rotational Mixing & Convective-Core Overshoot in Stars Using the Initial-Final Mass Relation
• Initial-Final Mass Relation for 3 to 4 M${}_{\odot }$ Progenitors of White Dwarfs from the Single Cluster NGC 2099
• Core-envelope decoupling drives radial shear dynamos in cool stars
• Activity and Kinematics of White Dwarf-M Dwarf Binaries from the SUPERBLINK Proper Motion Survey
• Photospheric carbon and oxygen abundances of F-G type stars in the Pleiades cluster
• Mind the Gap I: H$\alpha$ Activity of M Dwarfs Near the Partially/Fully Convective Boundary and a New H$\alpha$ Emission Deficiency Zone on the Main Sequence

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• A population synthesis study of the Gaia 100 pc unresolved white dwarf-main sequence binary population
• A magnitude-limited catalogue of unresolved white dwarf-main sequence binaries from Gaia DR3
• ChronoFlow: A Data-Driven Model for Gyrochronology
• A modest change in magnetic braking at the fully convective boundary explains cataclysmic variable evolution
• 200,000+ Deep Learning-inferred Periods of Stellar Variability from the All-Sky Automated Survey for Supernovae
• The Solar Neighborhood. LV. M Dwarf Twin Binaries -- One in Five Twin Sibling Pairs Are Mismatched in Activity and/or Rotation
• Mechanisms for magnetic braking boost and disruption: the role of irradiation-driven winds and convective turnover time spike in cataclysmic variables