Angular momentum transport and element mixing in the stellar interior I. Application to the rotating Sun

TL;DR

This paper develops a diffusion-based model for magnetic angular momentum and element transport in the Sun, improving agreement with helioseismic observations and elucidating magnetic fields' role in stellar interior dynamics.

Contribution

It introduces a diffusion coefficient dependent on stellar parameters to model magnetic angular momentum and material transport, enhancing solar interior modeling accuracy.

Findings

Model aligns better with helioseismic data on solar rotation.

Magnetic fields effectively redistribute angular momentum.

Material mixing improves sound-speed profile accuracy.

Abstract

The purpose of this work was to obtain diffusion coefficient for the magnetic angular momentum transport and material transport in a rotating solar model. We assumed that the transport of both angular momentum and chemical elements caused by magnetic fields could be treated as a diffusion process. The diffusion coefficient depends on the stellar radius, angular velocity, and the configuration of magnetic fields. By using of this coefficient, it is found that our model becomes more consistent with the helioseismic results of total angular momentum, angular momentum density, and the rotation rate in a radiative region than the one without magnetic fields. Not only can the magnetic fields redistribute angular momentum efficiently, but they can also strengthen the coupling between the radiative and convective zones. As a result, the sharp gradient of the rotation rate is reduced at the bottom of the convective zone. The thickness of the layer of sharp radial change in the rotation rate is about 0.036 $R_{\odot}$ in our model. Furthermore, the difference of the sound-speed square between the seismic Sun and the model is improved by mixing the material that is associated with angular momentum transport.