New results on the submillimeter polarization spectrum of the Orion Molecular Cloud

Abstract

We have used the SHARP polarimeter at the Caltech Submillimeter Observatory to map the polarization at wavelengths of 350 and 450 μm in a ~2' × 3' region of the Orion Molecular Cloud. The map covers the brightest region of the OMC-1 ridge including the Kleinmann-Low (KL) nebula and the submillimeter source Orion-south. The ratio of 450 to 350 μm polarization is ~1.3 ± 0.3 in the outer parts of the cloud and drops by more than a factor of 2 toward KL. The outer cloud ratio is consistent with measurements in other clouds at similar wavelengths and confirms previous measurements placing the minimum of the polarization ratio in dusty molecular clouds at λ ~ 350 μm .

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