Stellar Outflows Driven by Magnetized Wide-Angle Winds
  We present two-dimensional, cylindrically symmetric simulations of hydrodynamic and magnetohydrodynamic (MHD) wide-angle winds interacting with a collapsing environment. These simulations have direct relevance to young stellar objects (YSOs). The results may also be of use in the study of collimated outflows from proto-planetary and planetary nebulae. We study a range of wind configurations consistent with asymptotic MHD wind collimation. The degree of collimation is parameterized by the ratio of the wind density at the pole to that of the equator. We find that a toroidal magnetic field can have a significant influence on the resulting outflow, giving rise to a very dense, jet-like flow in the post-shock region. The properties of the flow in this region are similar to the asymptotic state of a collimated MHD wind. We conclude that wide-angle MHD winds are quite likely capable of driving molecular outflows. Due to difficulty in treating MHD winds ab-initio in simulations we choose magnetic field strengths in the wind consistent slow magnetic rotators. While MHD launched winds will be in the fast rotator regime we discuss how our results, which rely on toroidal pinch effects, will hold for stronger field strengths. 
T. A. Gardiner, A. Frank and L. Hartmann