Trans-Alfvenic Motions in the Taurus Molecular Cloud
  Magnetically aligned velocity anisotropy over varying physical conditions and
environments within the Taurus Molecular Cloud is evaluated from analysis of
wide field spectroscopic imaging of 12CO and 13CO J=1-0 emission. Such
anisotropy is a result of MHD turbulence in the strong magnetic field regime
and provides an indirect measure of the role of magnetic fields upon the gas.
Velocity anisotropy aligned with the local, projected mean magnetic field
direction is limited to fields with low surface brightness 12CO emission
corresponding to regions of low visual extinction and presumably, low gas
volume density. The more optically thin 13CO J=1-0 emission shows little
evidence for velocity anisotropy. We compare our results with computational
simulations with varying degrees of magnetic field strength and Alfvenic Mach
numbers. In the diffuse, molecular envelope of the cloud, a strong magnetic
field and sub-Alfvenic turbulent motions are inferred. Super-Alfvenic motions
are present within the high column density filaments of the Taurus cloud. From
this trans-Alfvenic flow, we constrain the scaling exponent, kappa, of the
magnetic field density relation (B ~ n^kappa) to be near zero as expected for
ambipolar diffusion or material loading of magnetic flux tubes.
