Showing papers by "Jason Glenn published in 1999"

Magnetic Fields in Star Formation Regions: 1.3 Millimeter Continuum Polarimetry

Abstract: We present a nine-point λ=1.3 mm continuum polarization map of the inner arcminute of the DR 21 cloud core. The polarization and position angles are very uniform, and the inferred magnetic field (P.A.~75°) is nearly orthogonal to the cloud elongation (P.A.~7°). Applying the virial theorem and comparing the continuum polarimetry, we find that the magnetic field strength must be greater than a few mG to have a significant impact. Turbulent gas motions are probably a more significant source of support against self-gravity in the cloud core than in the magnetic field. We also report a survey of the λ=1.3 mm polarization of 14 star-forming cloud cores (P=1.6%). The λ=1.3 mm distribution is similar to the λ=100 μm and λ=800 μm polarization distributions in the literature except that the 1.3 mm distribution peaks at P 1.5×107 cm-3 than for those with nH2<1.5×107 cm-3. The sky-plane projection of the magnetic field lines in the seven elongated cloud cores with 800 μm or 1.3 mm polarization detections greater than 3 σ appear randomly distributed with respect to the position angles of cloud core elongations. This implies that magnetic fields do not provide substantial anisotropic support against self-gravity in this sample of star-forming cloud cores. The magnetic fields in the cloud cores also appear randomly oriented with respect to the Galactic plane.