On the Effect of Magnetic Spots on Stellar Winds and Angular Momentum Loss

O. Cohen, J. J. Drake, V. L. Kashyap, T. I. Gombosi

Published 2009-05-12Version 1

We simulate the effect of latitudinal variations in the location of star spots, as well as their magnetic field strength, on stellar angular momentum loss to the stellar wind. We use the Michigan solar corona global MagnetoHydroDynamic model, which incorporates realistic relation between the magnetic field topology and the wind distribution. We find that the spots location significantly affects the stellar wind structure, and as a result, the total mass loss rate and angular momentum loss rate. In particular, we find that the angular momentum loss rate is controlled by the mass flux when spots are located at low latitudes but is controlled by an increased plasma density between the stellar surface and the Alfven surface when spots are located at high latitudes. Our results suggest that there might be a feedback mechanism between the magnetic field distribution, wind distribution, angular momentum loss through the wind, and the motions at the convection zone that generate the magnetic field. This feedback might explain the role of coronal magnetic fields in stellar dynamos.