MAGNETOCENTRIFUGALLY DRIVEN FLOWS YOUNG STARS AND DISKS .3. NUMERICAL-SOLUTION OF THE SUB-ALFVENIC REGION

We construct steady, axisymmetric, numerical models of the sub-Alfvenic regions of cool winds driven by the X-celerator mechanism. We find that smooth acceleration to speeds of the order of the escape speed accompanied by substantial collimation of the flow can be achieved within the Alfven surface, located characteristically at several stellar radii. We apply the nondimensional results to winds which emerge from the equator of magnetized YSOs rotating at breakup and from circumstellar disks interacting with the magnetospheres of slowly rotating T Tauri stars. Stellar magnetic fields of kilogauss strength can drive wind mass-loss rates of 10(-6) M. yr-1 from rapidly accreting YSOs and 10(-8) M. yr-1 from slowly accreting T Tauri stars. The X-celerator mechanism can accelerate winds from these systems to velocities of hundreds of km s-1 within a few stellar radii in the case of embedded YSOs and approximately 10 stellar radii in the case of T Tauri stars.