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M. Heyer, H. Gong (University of Massachusetts), C. Brunt (University of Exeter), E. Ostriker (University of Maryland)
The presence of MHD turbulence in the Taurus Molecular Cloud is examined from 12CO and 13CO J=1-0 imaging observations using the FCRAO 14~meter telescope. The degree of velocity anisotropy is measured from velocity structure functions derived separately along the x and y axes using Principal Component Analysis of spectroscopic imaging data (Brunt & Heyer 2002). Such anisotropy is predicted from model descriptions and computational simulations of MHD turbulence in the case of strong magnetic fields (Goldreich & Sridhar 1995; Cho, Lazarian, & Vishniac 2002; Vestuto, Ostriker, & Stone 2003). Within a subfield of the Taurus image where the column densities are low, this velocity anisotropy is largest along an angle that is coincident with the local magnetic field direction determined independently from optical polarization of background stars.The structure function derived from data perpendicular to the local field shows a shallower scaling exponent and a larger scaling coefficient than the values that describe the structure function constructed along the magnetic field as predicted by the MHD models. This alignment provides strong evidence that the magnetic field is a significant dynamical force within this column density regime of the Taurus cloud.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.