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Abstract: The stability of large-scale magnetic fields in rotating stars is explored,using 3D numerical hydrodynamics to follow the evolution of an initial poloidalfield. It is found that the field is subject to an instability, locatedinitially on the magnetic equator, whereby the gas is displaced in a directionparallel to the magnetic axis. If the magnetic axis is parallel to the rotationaxis, the rotation does not affect the initial linear growth of theinstability, but does restrict the growth of the instability outside of theequatorial zone. The magnetic energy decays on a timescale which is a functionof the Alfv\-en crossing time and the rotation speed, but short compared to anyevolutionary timescale. No evidence is found for a possible stable end state toevolve from an initial axisymmetric poloidal field. The field of an obliquerotator is similarly unstable, in both cases regardless of the rotation speed.

Autor: J. Braithwaite (MPA Garching, CITA Toronto)


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