We present 2D MHD simulations of radiatively driven winds from a hot star having a dipole magnetic field aligned with the star's rotation axis. We focus in particular on a model with a moderately rapid rotation (about half the critical value), and also a strong magnetic confinement parameter, η_* B_e~2qR_*~/M_v = 600. The magnetic field channels and torques the wind outflow into an equatorial, rigidly rotating disk extending from near the Keplerian co-rotation radius outwards. The strong centrifugal force on material in the outer edge of this disk stretches the magnetic loops, leading to episodic breakout of mass when the field reconnects. The associated dissipation of magnetic energy heats material to temperatures of nearly 108 K, high enough to emit hard (several keV) X-rays. Such centrifugal mass ejection represents a novel mechanism for explaining X-ray flares recently observed in the magnetic Bp star σ Ori E.
展开▼
