The relative orientation between the magnetic field and gradients of
  surface brightness within thin velocity slices of 12CO and 13CO emission from
  the Taurus molecular cloud
  We examine the role of the interstellar magnetic field to modulate the
orientation of turbulent flows within the Taurus molecular cloud using spatial
gradients of thin velocity slices of 12CO and 13CO antenna temperatures. Our
analysis accounts for the random errors of the gradients that arise from the
thermal noise of the spectra. The orientations of the vectors normal to the
antenna temperature gradient vectors are compared to the magnetic field
orientations that are calculated from Planck 353~GHz polarization data. These
relative orientations are parameterized with the projected Rayleigh statistic
and mean resultant vector. For 12CO, 28 percent and 39 percent of the cloud
area exhibit strongly parallel or strongly perpendicular relative orientations
respectively. For the lower opacity 13CO emission, strongly parallel and
strongly perpendicular orientations are found in 7 percent and 43 percent of
the cloud area respectively. For both isotopologues, strongly parallel or
perpendicular alignments are restricted to localized regions with low levels of
turbulence. If the relative orientations serve as an observational proxy to the
Alfvenic Mach number then our results imply local variations of the Alfvenic
Mach number throughout the cloud.
