The possible role of meridional flows in suppressing magnetic buoyancy

Abstract

The equation of motion for a toroidal flux ring in a stellar convective envelope is derived, and the equilibrium of such a ring is considered. Necessary conditions for the stability of toroidal flux rings are derived, and results of stability calculations for a particular model of the meridional flow are presented. The motions of the flux rings when the rings are far from their equilibrium position or when equilibrium does not exist are considered. The results confirm the linear stability analysis, and show that in the absence of stable equilibrium, the rings move toward the solar surface along a trajectory which is parallel to the rotation axis. It is expected that viscosity will tend to reduce the rotational velocity difference between the flux ring and its surroundings, thus reducing the Coriolis force and altering the equilibrium. The storage time of toroidal flux rings is estimated, and some implications for the sun are discussed.