Asteroseismic measurement of core and envelope rotation rates for 2006 red giant branch stars

Abstract

Tens of thousands of red giant stars in the Kepler data exhibit solar-like oscillations. Their oscillations enable us to study the internal physics from core to surface, such as differential rotation. However, envelope rotation rates have been measured for only a dozen RGB stars so far. The limited sample hinders the theoretical interpretation of angular momentum transport in post-main-sequence phases. We apply a new approach to calculate the asymptotic frequencies of mixed modes, which accounts for the so-called near-degeneracy effects and leads to more proper measurements of envelope rotation rates. By fitting these asymptotic expressions to the observations, we obtain measurements of the properties of g modes and mean core and envelope rotation rates. Among 2495 stars with clear mixed-mode patterns, we found that 800 show doublets and 1206 show triplets, doubling the size of pre-existing catalogues. This led us to discover an over-density of stars that narrowly distribute around a well-defined ridge in the plane showing core rotation rate versus evolution along the RGB. With this work, we also increase the sample of stars with measured envelope rotation rates by two orders of magnitude. We find a decreasing trend between envelope rotation rates and evolution, implying that the envelopes slow down with expansion, as expected. We find 243 stars whose envelope rotation rates are significantly larger than zero. For these stars, the core-to-envelope rotation ratios are around 20 and show a large spread with evolution. Several stars show extremely mild differential rotations, with core-to-surface ratios between 1 and 2. These stars also have very slow core rotation rates, suggesting that they go through a peculiar rotational evolution. We also discovered more stars located below the degeneracy sequence, which will provide the opportunity to study the history of possible stellar mergers.

arXiv comment21 pages, 16 figures in the main text and 7 figures in the appendix. Accepted for publication by A&A

References in corpus (88)

• emcee: The MCMC Hammer
• Modules for Experiments in Stellar Astrophysics (MESA)
• Rotation Periods of 34,030 Kepler Main-Sequence Stars: The Full Autocorrelation Sample
• Gravity modes as a way to distinguish between hydrogen- and helium-burning red giant stars
• Fast core rotation in red-giant stars revealed by gravity-dominated mixed modes
• Spin down of the core rotation in red giants
• ADIPLS -- the Aarhus adiabatic oscillation package
• Seismic evidence for a rapidly rotating core in a lower-giant-branch star observed with Kepler
• Slowing the Spins of Stellar Cores
• Seismic constraints on the radial dependence of the internal rotation profiles of six Kepler subgiants and young red giants
• Seismic diagnostics for transport of angular momentum in stars 1. Rotational splittings from the PMS to the RGB
• Angular Momentum Transport in Stellar Interiors
• Angular momentum transport within evolved low-mass stars
• 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
• Asteroseismic classification of stellar populations among 13000 red giants observed by Kepler
• Rotational velocities of A-type stars. III. Velocity distributions
• Solar-like oscillations in low-luminosity red giants: first results from Kepler
• Asteroseismology of 16000 Kepler Red Giants: Global Oscillation Parameters, Masses, and Radii
• Mixed modes in red giants: a window on stellar evolution
• The interior rotation of a sample of gamma Doradus stars from ensemble modelling of their gravity mode period spacings
• Angular momentum transport in stellar interiors constrained by rotational splittings of mixed modes in red giants
• 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
• Seismic evidence for a weak radial differential rotation in intermediate-mass core helium burning stars
• General Cosmography Model with Spatial Curvature
• Transport and mixing in the radiation zones of rotating stars: I-Hydrodynamical processes
• Core rotation braking on the red giant branch for various mass ranges
• A prevalence of dynamo-generated magnetic fields in the cores of intermediate-mass stars
• Planet Engulfment by ~1.5-3 Solar-Mass Red Giants
• Seismic diagnostics for transport of angular momentum in stars 2. Interpreting observed rotational splittings of slowly-rotating red giant stars
• Angular Momentum Transport via Internal Gravity Waves in Evolving Stars
• Nearly-uniform internal rotation of solar-like main-sequence stars revealed by space-based asteroseismology and spectroscopic measurements
• 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
• γ Doradus stars as test of angular momentum transport models
• Internal rotation of the red-giant star KIC 4448777 by means of asteroseismic inversion
• Structural glitches near the cores of red giants revealed by oscillations in g-mode period spacings from stellar models
• 30 to 100-kG magnetic fields in the cores of red giant stars
• Period spacings in red giants IV: Toward a complete description of the mixed-mode pattern
• Angular momentum transport efficiency in post-main sequence low-mass stars
• Dipole modes with depressed amplitudes in red giants are mixed modes
• Rotation of the convective core in $\gamma$ Dor stars measured by dips in period spacings of g modes coupled with inertial modes
• Seismic evidence for near solid-body rotation in two Kepler subgiants and implications for angular momentum transport
• Theoretical power spectra of mixed modes in low mass red giant stars
• Strong magnetic fields detected in the cores of 11 red giant stars using gravity-mode period spacings
• Generation of internal gravity waves by penetrative convection
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. I. Efficiency of transport during the subgiant phase
• Anisotropic turbulent transport in stably stratified rotating stellar radiation zones
• Magnetic signatures on mixed-mode frequencies. I. An axisymmetric fossil field inside the core of red giants
• Angular momentum redistribution by mixed modes in evolved low-mass stars. I. Theoretical formalism
• Period spacings in red giants; III. Coupling factors of mixed modes
• On deriving p-mode parameters for inclined solar-like stars
• Internal rotation of 13 low-mass low-luminosity red giants in the Kepler field
• The effect of tides on near-core rotation: analysis of 35 Kepler $\gamma$ Doradus stars in eclipsing and spectroscopic binaries
• Discovery of post-mass-transfer helium-burning red giants using asteroseismology
• The angular momentum transport by unstable toroidal magnetic fields
• Rotation of Giant Stars
• Near-degeneracy effects on the frequencies of rotationally-split mixed modes in red giants
• Rotation in stellar interiors: General formulation and an asteroseismic-calibrated transport by the Tayler instability
• Constraining differential rotation of Sun-like stars from asteroseismic and starspot rotation periods
• 3D evolution of magnetic fields in a differentially rotating stellar radiative zone
• Magnetic braking of stellar cores in red giants and supergiants
• Seismic signature of electron degeneracy in the core of red giants: hints for mass transfer between close red-giant companions
• Spin-down by dynamo action in simulated radiative stellar layers
• Dynamical tide in stellar radiative zones. General formalism and evolution for low-mass stars
• Asteroseismic Fingerprints of Stellar Mergers
• Effect of a strong magnetic field on gravity-mode period spacings in red giant stars
• Effects of a strong magnetic field on internal gravity waves: trapping, phase mixing, reflection and dynamical chaos
• Probing the mid-layer structure of red giants I. Mixed-mode coupling factor as a seismic diagnosis
• Asymmetries of frequency splittings of dipolar mixed modes: a window on the topology of deep magnetic fields
• Angular momentum transport by magnetic fields in main sequence stars with Gamma Doradus pulsators
• Topology and obliquity of core magnetic fields in shaping seismic properties of slowly rotating evolved stars
• Magnetic signatures on mixed-mode frequencies. II. Period spacings as a probe of the internal magnetism of red giants
• Gravity mode offset and properties of the evanescent zone in red-giant stars
• A close-in giant planet escapes engulfment by its star
• Variations of the mixing character of dipolar mixed modes in red giant stars
• Inverse Tides in Pulsating Binary Stars
• Core magnetic field imprint in the non-radial oscillations of red giant stars
• Numerical simulations of the Tayler-Spruit dynamo in proto-magnetars
• 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 Mode Asteroseismology of Red Giant Stars Through the Luminosity Bump
• Spinning up the Surface: Evidence for Planetary Engulfment or Unexpected Angular Momentum Transport?
• First Observational Signature of Rotational Deceleration in a Massive, Intermediate-age Star Cluster in the Magellanic Clouds
• Some glimpses from helioseismology at the dynamics of the deep solar interior
• Mode Mixing and Rotational Splittings: I. Near-Degeneracy Effects Revisited

Cited by in corpus (18)

• APOKASC-3: The Third Joint Spectroscopic and Asteroseismic catalog for Evolved Stars in the Kepler Fields
• Evidence that Mass Loss on the Red Giant Branch Decreases with Metallicity
• Unveiling complex magnetic field configurations in red giant stars
• Seismic differences between solar magnetic cycles 23 and 24 for low-degree modes
• Magnetic Webs in Stellar Radiative Zones
• Nonlinear internal waves breaking in stellar radiation zones. Parametrisation for the transport of angular momentum: bridging geophysical to stellar fluid dynamics
• Asteroseismology with PBjam 2.0: measuring dipole mode frequencies in coupling regimes from main sequence to low-luminosity red giant stars
• The efficiency of mixed modes for angular momentum transport
• Seismic detection of core magnetic fields in red giants using the gravity offset
• Wave-Driven Mixing Enhanced by Rotation in Red Giant Branch Stars
• Beyond MESA Defaults: The Impact of Structural Resolution Uncertainty in p-mode Asteroseismology
• Asteroseismic Imprints of Mass Transfer in Binary Stars: Probing the Interiors of Donors and Accretors with Gravity and Acoustic Modes
• The highest mass Kepler red giants -- II. Spectroscopic parameters, the amplitude-activity relation, and unexpected halo orbits
• Engulfment of a hot Jupiter as a possible origin of the rapid spin and internal spin misalignment of the planet-hosting red giant Kepler-56
• Impact of near-degeneracy effects on linear rotational inversions for red-giant stars
• Near-critical magnetic fields in Kepler red giants
• 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