MAGNETIC FIELDS IN STAR-FORMING MOLECULAR CLOUDS. IV. POLARIMETRY OF THE FILAMENTARY NGC 2068 CLOUD IN ORION B

摘要

We present submillimeter polarimetry at 850μm toward the filamentary star-forming region associated with the reflection nebulosity NGC 2068 in Orion B. These data were obtained using the James Clerk Maxwell Telescope's Submillimeter Common-User Bolometric Array polarimeter. The polarization pattern observed is not consistent with that expected for a field geometry defined by a single mean field direction. There are three distinct distributions of polarization angle, which could represent regions of differing inclination and/or field geometry within the filamentary gas. In general, the polarization pattern does not correlate with the underlying total dust emission. The presence of varying inclinations against the plane of the sky is consistent with the comparison of the 850μm continuum emission to the optical emission from the Palomar Observatory Sky Survey, which shows that the western dust emission lies in the foreground of the optical nebula, while the eastern dust emission originates in the background. Percentage polarizations are high, particularly toward the northeast region of the cloud. The mean polarization percentage in the region is 5.0% with a standard deviation of 3.1%. Depolarization toward high intensities is identified in all parts of the filament.