UC San Diego

Structures of the magnetic field and velocity in stars are discussed based on the mean field MHD equations. A special case is presented, where the solution is constructed by the Beltrami solution in the stellar convection zone with the symmetry in the azimuthal direction. Magnetic field lines form concentric toroidal magnetic surfaces. The cross-helicity dynamo mechanism induces a mean flow of plasmas. The structure of this driven flow is also shown to constitute toroidal surfaces. Considering the symmetry and the relation of this toroidal magnetic structure with the polarity, it is shown that the latitudinal component of this flow is pole-ward in the northern as well as southern hemispheres. This gives an insight into the role of the magnetic field for the meridional flow. © 2006, Astronomical Society of Japan.