Asteroseismic Signatures of Core Magnetism and Rotation in Hundreds of Low-Luminosity Red Giants

Abstract

Red Giant stars host solar-like oscillations which have mixed character, being sensitive to conditions both in the outer convection zone and deep within the interior. The properties of these modes are sensitive to both core rotation and magnetic fields. While asteroseismic studies of the former have been done on a large scale, studies of the latter are currently limited to tens of stars. We aim to produce the first large catalogue of both magnetic and rotational perturbations. We jointly constrain these parameters by devising an automated method for fitting the power spectra directly. We successfully apply the method to 302 low-luminosity red giants. We find a clear bimodality in core rotation rate. The primary peak is at $\delta {\nu }_{\mathrm{rot}}$ = 0.32 $\mu$Hz, and the secondary at $\delta {\nu }_{\mathrm{rot}}$ = 0.47 $\mu$Hz. Combining our results with literature values, we find that the percentage of stars rotating much more rapidly than the population average increases with evolutionary state. We measure magnetic splittings of 2$\sigma$ significance in 23 stars. While the most extreme magnetic splitting values appear in stars with masses > 1.1M${}_{\odot }$, implying they formerly hosted a convective core, a small but statistically significant magnetic splitting is measured at lower masses. Asymmetry between the frequencies of a rotationally split multiplet has previously been used to diagnose the presence of a magnetic perturbation. We find that of the stars with a significant detection of magnetic perturbation, 43\% do not show strong asymmetry. We find no strong evidence of correlation between the rotation and magnetic parameters.

arXiv comment18 pages, 23 figures, accepted for publication in MNRAS

References in corpus (58)

• emcee: The MCMC Hammer
• Modules for Experiments in Stellar Astrophysics (MESA)
• Modules for Experiments in Stellar Astrophysics (MESA): Giant Planets, Oscillations, Rotation, and Massive Stars
• MESA Isochrones and Stellar Tracks (MIST). I: Solar-Scaled Models
• dynesty: A Dynamic Nested Sampling Package for Estimating Bayesian Posteriors and Evidences
• MESA Isochrones and Stellar Tracks (MIST) 0: Methods for the construction of stellar isochrones
• Dynamo action by differential rotation in a stably stratified stellar interior
• Slowing the Spins of Stellar Cores
• Seismic diagnostics for transport of angular momentum in stars 1. Rotational splittings from the PMS to the RGB
• Angular momentum transport within evolved low-mass stars
• The connection between stellar granulation and oscillation as seen by the Kepler mission
• Standing on the shoulders of Dwarfs: the $Kepler$ asteroseismic LEGACY sample I - oscillation mode parameters
• Probing the core structure and evolution of red giants using gravity-dominated mixed modes observed with Kepler
• Asteroseismology of 16000 Kepler Red Giants: Global Oscillation Parameters, Masses, and Radii
• A new correction of stellar oscillation frequencies for near-surface effects
• Mixed modes in red giants: a window on stellar evolution
• Angular momentum transport in stellar interiors constrained by rotational splittings of mixed modes in red giants
• Testing the asteroseismic scaling relations for Red Giants with Eclipsing Binaries Observed by Kepler
• Period spacings in red giants II. Automated measurement
• Asteroseismology Can Reveal Strong Internal Magnetic Fields in Red Giant Stars
• The universal red-giant oscillation pattern; an automated determination with CoRoT data
• Core rotation braking on the red giant branch for various mass ranges
• Seismic diagnostics for transport of angular momentum in stars 2. Interpreting observed rotational splittings of slowly-rotating red giant stars
• Period spacings in red giants I. Disentangling rotation and revealing core structure discontinuities
• Understanding angular momentum transport in red giants: the case of KIC 7341231
• AIMS - A new tool for stellar parameter determinations using asteroseismic constraints
• Establishing the accuracy of asteroseismic mass and radius estimates of giant stars. I. Three eclipsing systems at [Fe/H]~ -0.3 and the need for a large high-precision sample
• 30 to 100-kG magnetic fields in the cores of red giant stars
• The magnetic fields of intermediate-mass T Tauri stars : I. Magnetic detections and fundamental stellar parameters
• Angular momentum transport efficiency in post-main sequence low-mass stars
• Period spacings in red giants IV: Toward a complete description of the mixed-mode pattern
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum II. Test of a revised prescription for transport by the Tayler instability
• Oscillating red giants in eclipsing binary systems: empirical reference value for asteroseismic scaling relation
• Study of KIC 8561221 observed by Kepler: an early red giant showing depressed dipolar modes
• Strong magnetic fields detected in the cores of 11 red giant stars using gravity-mode period spacings
• Magnetic signatures on mixed-mode frequencies. I. An axisymmetric fossil field inside the core of red giants
• Period spacings in red giants; III. Coupling factors of mixed modes
• Active red giants: close binaries versus single rapid rotators
• Rotation in stellar interiors: General formulation and an asteroseismic-calibrated transport by the Tayler instability
• Asteroseismology of 36 \emph{Kepler} subgiants -- I. Oscillation frequencies, linewidths and amplitudes
• New insights on the interior of solar-like pulsators thanks to CoRoT: the case of HD 49385
• PBjam: A Python package for automating asteroseismology of solar-like oscillators
• Asteroseismology of 3,642 Kepler Red Giants: Correcting the Scaling Relations based on Detailed Modeling
• Magnetic braking of stellar cores in red giants and supergiants
• Probing the internal magnetic field of slowly pulsating B-stars through g modes
• Spin-down by dynamo action in simulated radiative stellar layers
• Origin and evolution of magnetic fields in PMS stars : influence of rotation and structural changes
• Topology and obliquity of core magnetic fields in shaping seismic properties of slowly rotating evolved stars
• Asymmetries of frequency splittings of dipolar mixed modes: a window on the topology of deep magnetic fields
• Magnetic signatures on mixed-mode frequencies. II. Period spacings as a probe of the internal magnetism of red giants
• Core magnetic field imprint in the non-radial oscillations of red giant stars
• Automated approach to measure stellar inclinations: validation through large-scale measurements on the red giant branch
• Mode Mixing and Rotational Splittings: II. Reconciling Different Approaches to Mode Coupling
• Mixed Modes and Asteroseismic Surface Effects: I. Analytic Treatment
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. VI. Testing a parametric formulation for the azimuthal magneto-rotational instability
• Mixed Modes and Asteroseismic Surface Effects: II. Subgiant Systematics
• Angular momentum transport in a contracting stellar radiative zone embedded in a large scale magnetic field
• Reggae: A Parametric Tuner for PBJam, and a Visualization Tool for Red Giant Oscillation Spectra

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• Asymptotic power spectra and visibilities of damped mixed modes
• Magneto-Archeology of White Dwarfs. Revisiting the fossil field scenario with observational constraints during the red giant branch
• Near-critical magnetic fields in Kepler red giants
• Pushing the Limit of Asteroseismic Detection for Cool Dwarfs using TESS and Deep Learning
• Co-existence of Internal Gravity Waves and Tayler-Spruit Magnetic Fields in the Radiative Core of Low-mass Stars
• Near-degeneracy effects in Quadrupolar Mixed Modes. From an Asymptotic Description to Data Fitting