On the problem of solar magnetic field generation

Abstract

Generation of a nonaxisymmetric, predominantly toroidal magnetic field in the convective layer of the Sun is considered assuming that the process is related to a decrease in the energy consumed for the convective heat transfer. It is also assumed that the field is antisymmetric relative to the equatorial plane and the field strength varies in proportion to the sine or cosine of the azimuthal angle. It is shown that the field strength increases when both a radial gradient of the angular rotation velocity and a steady-state axisymmetric meridional substance circulation are present. A change in the direction of the poloidal motion (leading to a change in the overall field sign) is assumed to take place on attaining a limiting field strength. This is probably related to the excitation of the corresponding turbulent medium viscosity. In the proposed model, a restart of the field generation process is induced by a change in the magnetic field sign.