Angular momentum transport efficiency in post-main sequence low-mass stars

Abstract

Context. Using asteroseismic techniques, it has recently become possible to probe the internal rotation profile of low-mass (~1.1-1.5 Msun) subgiant and red giant stars. Under the assumption of local angular momentum conservation, the core contraction and envelope expansion occurring at the end of the main sequence would result in a much larger internal differential rotation than observed. This suggests that angular momentum redistribution must be taking place in the interior of these stars. Aims. We investigate the physical nature of the angular momentum redistribution mechanisms operating in stellar interiors by constraining the efficiency of post-main sequence rotational coupling. Methods. We model the rotational evolution of a 1.25 Msun star using the Yale Rotational stellar Evolution Code. Our models take into account the magnetic wind braking occurring at the surface of the star and the angular momentum transport in the interior, with an efficiency dependent on the degree of internal differential rotation. Results. We find that models including a dependence of the angular momentum transport efficiency on the radial rotational shear reproduce very well the observations. The best fit of the data is obtained with an angular momentum transport coefficient scaling with the ratio of the rotation rate of the radiative interior over that of the convective envelope of the star as a power law of exponent ~3. This scaling is consistent with the predictions of recent numerical simulations of the Azimuthal Magneto-Rotational Instability. Conclusions. We show that an angular momentum transport process whose efficiency varies during the stellar evolution through a dependence on the level of internal differential rotation is required to explain the observed post-main sequence rotational evolution of low-mass stars.

8 pages, 6 figures; accepted for publication in Astronomy & Astrophysics

References in corpus (11)

• A spin-down clock for cool stars from observations of a 2.5-billion-year-old cluster
• YREC: The Yale Rotating Stellar Evolution Code
• Seismic evidence for a weak radial differential rotation in intermediate-mass core helium burning 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
• Rotational evolution of slow-rotators sequence stars
• Dynamics of the solar tachocline II: the stratified case
• Destabilisation of hydrodynamically stable rotation laws by azimuthal magnetic fields
• The angular momentum transport by unstable toroidal magnetic fields
• Rotational splitting as a function of mode frequency for six Sun-like stars
• How Efficient is Rotational Mixing in Massive Stars ?

Cited by in corpus (46)

• Slowing the Spins of Stellar Cores
• Core rotation braking on the red giant branch for various mass ranges
• On the competing effect of wind braking and interior coupling in the rotational evolution of solar-like stars
• Constraining the efficiency of angular momentum transport with asteroseismology of red giants: the effect of stellar mass
• The spins of compact objects born from helium stars in binary systems
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum II. Test of a revised prescription for transport by the Tayler instability
• Can plume-induced internal gravity waves regulate the core rotation of subgiant stars?
• Seismic evidence for near solid-body rotation in two Kepler subgiants and implications for angular momentum transport
• Modeling of Magneto-Rotational Stellar Evolution I. Method and first applications
• Rotation rate of the solar core as a key constraint to magnetic angular momentum transport in stellar interiors
• 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
• Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal components
• Lithium depletion and angular momentum transport in solar-type stars
• Compact Binary Coalescences: Astrophysical Processes and Lessons Learned
• Common dynamo scaling in slowly rotating young and evolved stars
• Asteroseismic measurement of core and envelope rotation rates for 2006 red giant branch stars
• Asteroseismic Signatures of Core Magnetism and Rotation in Hundreds of Low-Luminosity Red Giants
• Lithium depletion and angular momentum transport in F-type and G-type stars in Galactic open clusters
• Constraining transport of angular momentum in stars: Combining asteroseismic observations of core helium burning stars and white dwarfs
• Probing the mid-layer structure of red giants I. Mixed-mode coupling factor as a seismic diagnosis
• Angular momentum transport by magnetic fields in main sequence stars with Gamma Doradus pulsators
• Horizontal shear instabilities in rotating stellar radiation zones: I. Inflectional and inertial instabilities and the effects of thermal diffusion
• A model of rotating convection in stellar and planetary interiors: II -- gravito-inertial wave generation
• The s process in rotating low-mass AGB stars. Nucleosynthesis calculations in models matching asteroseismic constraints
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. IV. Internal rotation of Kepler 56 from an MCMC analysis of the rotational splittings
• Magnetohydrodynamic Simulations of the Tayler Instability in Rotating Stellar Interiors
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. V. Efficiency of the transport on the red giant branch and in the red clump
• Asteroseismology of evolved stars to constrain the internal transport of angular momentum. VI. Testing a parametric formulation for the azimuthal magneto-rotational instability
• Robust asteroseismic properties of the bright planet host HD 38529
• Angular momentum transport, layering, and zonal jet formation by the GSF instability: nonlinear simulations at a general latitude
• The spins of stripped B stars support magnetic internal angular momentum transport
• Angular momentum transport in a contracting stellar radiative zone embedded in a large scale magnetic field
• Asteroseismic sensitivity to internal rotation along the red-giant branch
• A coherent view of Li depletion and angular momentum transport to explain the Li plateau -- from Population II to Population I stars
• Improved asteroseismic inversions for red-giant surface rotation rates
• Nonaxisymmetric MHD instabilities of Chandrasekhar states in Taylor-Couette geometry
• Angular momentum and lithium transport from main sequence to sub-giant and red giant low-mass stars
• Quasi-two-dimensional nonlinear evolution of helical magnetorotational instability in a magnetized Taylor-Couette flow
• The efficiency of mixed modes for angular momentum transport
• Magnetic field dynamos and magnetically triggered flow instabilities
• Constraining the Rotation Profile in a Low-Luminosity Subgiant with a Surface Rotation Measurement
• Stellar spots cause measurable variations in atmospheric metallicity
• Probing the internal magnetism of stars using asymptotic magneto-asteroseismology
• Impact of near-degeneracy effects on linear rotational inversions for red-giant stars
• Impact of tides on non-coplanar orbits of progenitors of high-mass X-ray binaries