Bipolar Molecular Outflows Driven by Hydromagnetic Protostellar Winds

We demonstrate that magnetically collimated protostellar winds will sweep ambient material into thin, radiative, momentum-conserving shells whose features reproduce those commonly observed in bipolar molecular outflows. We find that the typical position-velocity and mass-velocity relations occur in outflows in a wide variety of ambient density distributions, regardless of the time histories of their driving winds.