Modelling the Corona of HD 189733 in 3D
  The braking of main sequence stars originates mainly from their stellar wind. The efficiency of this angular momentum extraction depends on the rotation rate of the star, the acceleration profile of the wind and the coronal magnetic field. The derivation of scaling laws parametrizing the stellar wind torque is important for our understanding of gyro-chronology and the evolution of the rotation rates of stars. In order to understand the impact of complex magnetic topologies on the stellar wind torque, we present three- dimensional, dynamical simulations of the corona of HD 189733. Using the observed complex topology of the magnetic field, we estimate how the torque associated with the wind scales with model parameters and compare those trends to previously published scaling laws. 
Antoine Strugarek, Allan Sacha Brun, Sean P. Matt, Victor R\'eville,   Jean-Fran\c{c}ois Donati, Claire Moutou, Rim Fares
astro-ph.SR