Far‐infrared and Submillimeter Polarization of OMC‐1: Evidence for Magnetically Regulated Star Formation

Abstract

This paper presents large-scale polarization maps (8' x 8') of theOrion molecular cloud (OMC-1) at far-infrared (100 mu m; 35'' resolution)and submillimeter (350 mu m; 18'' resolution) wavelengths. The magneticfield shows a pinch at scales less than 0.5 pc with a centroid thatis on the OMC-1 ridge, a site of high-mass star formation. We inferthat gravitational collapse pulled the magnetic field into an hourglassshape. We estimate that the magnetic, kinetic, and gravitationalenergies are in equipartition on the ridge and that the magneticenergy dominates in the surrounding ambient envelope. We considera model in which the ridge and thus high-mass stars gravitationallycollapsed out of a cloud that was initially supported by the magneticfield. At flux peaks, there is a reduction in the percent polarization.This effect is discussed in relation to temperature, optical depth,and wavelength.