Magnetic channeling of radiatively driven hot-star winds

Massive, hot, luminous stars have strong stellar winds driven by line-scattering of the star's continuum radiation. Spectropolarimetric observations have detected substantial large-scale dipole magnetic fields for several hot stars. This paper discusses our recent efforts to carry out MHD simulations of the effect of magnetic fields in channeling and confining the wind outflow, with particular emphasis on the "Magnetically Confined Wind Shock" (MCWS) paradigm for explaining the relatively hard X-ray emission observed by the Chandra X-ray observatory for magnetic hot stars like Theta 1 Ori C. We also examine the effect of magnetic fields on the wind from a rotating star, showing that this can spin-up the outflowing material, but does not readily form a Keplerian "Magnetically Torqued Disk". We further describe a new "Rigidly Rotating Magnetosphere"(RRM) model that has proven highly successful in reproducing the rotational modulated Balmer emission seen in magnetic Bp stars like sigma Ori C. We conclude with an outlook for the general role of magnetic fields in structuring hot-star mass loss and circumstellar matter.