Magnetic confinement of dense plasma inside (and outside) stellar coronae : magnetic confinement in stellar coronae

Abstract

Magnetic confinement of dense plasma is found in the magnetospheres of both high and low mass stars. Trapped material traces the magnetic field structure, often at large distances from the star where the magnetic structure is otherwise difficult to observe. This work looks specifically at rapidly rotating, solar-like stars where this behaviour is well observed in the form of “slingshot” prominences. We have produced a model for generating cooled magnetic loops in equilibrium with a range of coronal magnetic fields. These loops can be used to populate model coronae and confine material at a wide range of heights above the stellar surface. We calculate masses for slingshot prominences for the star AB Doradus that are consistent with observational values. The model produces two types of solution: loops with summits at low heights and tall solutions beyond the co-rotation radius. We show that the low-lying solutions are footpoint heavy and generally follow the shape of the background field. We refer to these as solar-like prominences. The tall solutions are summit heavy and are centrifugally supported. These are are the slingshot prominences. These tall solutions can be found within the stellar wind, beyond the closed corona. Hα trails are generated for various coronal field structures with a range of field geometries and coronal extents. Similar Hα trails are produced by a range of global field structures, which implies that magnetic confinement of material should be common in rapidly rotating stars.