Magnetism in Interstellar Nurseries at 760 Microns

Abstract

The advent of telescopes operating in the extreme infrared (EIR \ submillimeter wavelengths) located at dry sites on mountain tops now permits observations of high dust and gas density (n D 2 ] 108 cm~3), small diameter (L D 0.06 pc ; 12000 AU) clumps inside large interstellar nurseries. Using the James Clerk Maxwell Telescope (JCMT) at 760 km (394 GHz) in the EIR, we present new total continuum maps and linear polarization observations of the dust emission and the associated magnetic Ðeld for 35 clumps within six interstellar nurseries (OMC, Orion B, NGC 6334, M0.25]0.01, W48, and S140) located within 8.5 kpc of the Sun. A principal result is that the mean clump gas density varies with mean clump size as SnT D SL T~1.5. In one-third of our cases, the magnetic Ðeld in clumps is nearly perpendicular to the ridge linking clumps (not random from clump to clump). The cloud elongation does not appear to have a preferred angle with respect to the Galactic plane ; we rule out models with a cloud magnetic Ðeld aligned with the large-scale galactic magnetic Ðeld. We Ðnd that the clump gravitational energy B the clump nonthermal kinetic energy, in many simple resolved nonconfused clumps, while other energy components are much smaller (magnetic, thermal, external pressure).