Angular momentum transport and element mixing in the stellar interior

I. Application to the rotating Sun

¹ National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, Kunming 650011, PR China e-mail: yangwuming@ynao.ac.cn;bislan@public.km.yn.cn
² Graduate School of The Chinese Academy of Sciences, Beijing 100039, PR China

Received: 6 June 2005
Accepted: 15 November 2005

Abstract

Aims.The purpose of this work was to obtain diffusion coefficient for the magnetic angular momentum transport and material transport in a rotating solar model.Methods.We assumed that the transport of both angular momentum and chemical elements caused by magnetic fields could be treated as a diffusion process. Results.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  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.