On the Geometry of the Near-Core Magnetic Field in Massive Stars
arXiv:2412.09986 · doi:10.3847/2041-8213/ad95f8
Abstract
It is well-known that the cores of massive stars sustain a stellar dynamo with a complex magnetic field configuration. However, the same cannot be said for the field's strength and geometry at the convective-radiative boundary, which are crucial when performing asteroseismic inference. In this Letter, we present three-dimensional (3D) magnetohydrodynamic (MHD) simulations of a 7 solar mass mid-main sequence star, with particular attention given to the convective-radiative boundary in the near-core region. Our simulations reveal that the toroidal magnetic field is significantly stronger than the poloidal field in this region, contrary to recent assumptions. Moreover, the rotational shear layer, also important for asteroseismic inference, is specifically confined within the extent of the buoyancy frequency peak. These results, which are based on the inferred properties of HD 43317, have widespread implications for asteroseismic studies of rotation, mixing and magnetism in stars. While we expect our results to be broadly applicable across stars with similar buoyancy frequency profiles and stellar masses, we also expect the MHD parameters and the initial stellar rotation rate to impact the geometry of the field and differential rotation at the convective-radiative interface.
References in corpus (17)
- Modules for Experiments in Stellar Astrophysics (MESA)
- Modules for Experiments in Stellar Astrophysics (MESA): Pulsating Variable Stars, Rotation, Convective Boundaries, and Energy Conservation
- Simulations of dynamo action in fully convective stars
- On magnetic instabilities and dynamo action in stellar radiation zones
- Simulations of core convection in rotating A-type stars: Magnetic dynamo action
- Internal mixing of rotating stars inferred from dipole gravity modes
- Signatures of internal rotation discovered in the Kepler data of five slowly pulsating B stars
- Gravito-inertial and pressure modes detected in the B3 IV CoRoT target HD 43317
- Probing the temperature gradient in the core boundary layer of stars with gravito-inertial modes: the case of KIC7760680
- Period spacings of gravity modes in rapidly rotating magnetic stars I. Axisymmetric fossil field with poloidal and toroidal components
- Asteroseismic inference of the near-core magnetic field strength in the main sequence B star HD 43317
- Evolution of solar and stellar dynamo theory
- Variability of newly identified B-type stars observed by Kepler
- Detecting axisymmetric magnetic fields using gravity modes in intermediate-mass stars
- Period spacings of gravity modes in rapidly rotating magnetic stars II. The case of an oblique dipolar fossil magnetic field
- The first two-dimensional stellar structure and evolution models of rotating stars
- Magnetic characterization of the SPB/ Cep hybrid pulsator HD 43317