Optical polarization maps of star-forming regions in Perseus, Taurus, and Ophiuchus

Abstract

New optical linear polarization maps are presented of the star-forming regions near L1506 in Taurus, L1755 in Ophiuchus, and the complex of dark cloud which extends from L1448 in B5 in Perseus. The former two show a well-defined peak magnetic field direction in the plane of the sky with a finite dispersion about that peak which is smaller than would be expected for a random distribution of field distributions. The dispersion in the position angle of filamentary clouds within these complexes implies that clouds which appear elongated on the plane of the sky are not all associated with a pattern of polarization vectors particularly 'parallel' or 'perpendicular' to their geometry. Instead, clouds tend to be oriented at the angle formed by their axis and the 'mean' direction of the local large-scale field. For the dark cloud complex, a bimodal distribution of the polarization vector angle is taken to result from at least two distributions of gas along the line of sight which appear as a 'complex' in projection.