Formation of buoyant magnetic structures by a localized velocity shear |
| |
Authors: | N. Brummell K. Cline F. Cattaneo |
| |
Affiliation: | 1JILA and Department of Astrophysical and Planetary Science, University of Colorado, Boulder, CO 80309-0440, USA;2Dept. of Mathematics, University of Chicago, Chicago, IL 60637, USA |
| |
Abstract: | Motivated by considerations of the solar tachocline, we study the generation of strong buoyant magnetic structures by a sheared velocity field localized in a convectively stable background, using non-linear three-dimensional (3D) magnetohydrodynamic (MHD) simulations. The shear flow can spontaneously create strong tube-like toroidal (streamwise) magnetic structures from an imposed weak uniform poloidal (cross-stream) magnetic field. The structures are magnetically buoyant and therefore rise, and may evolve further to a rich variety of geometries, including kinked or arched shapes. The emergence process can repeat indefinitely with a characteristic period. These mechanisms may be relevant to the MHD processes in the solar tachocline and the creation and emergence of solar active regions. |
| |
Keywords: | MHD Sun: interior Sun: magnetic fields stars: spots |
|
|