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Paper: Circular Polarization in Scattered Light and the Process of Light Scattering in OMC1
Volume: 449, Astronomical Polarimetry 2008: Science from Small to Large Telescopes
Page: 230
Authors: Matsumura, M.; Bastien, P.
Abstract: Large linear (pl) and circular (pc) polarization observed in star forming regions is believed to be due to scattering and/or extinction by aligned grains, although specific details of the process are not well known. We investigate the properties of polarization in scattered light by aligned ellipsoidal grains with the Fredholm integral equation method (FIM) and the T-matrix method (Tmat), and we apply the results to the observed circular polarization in a region south-east of the BN object (SEBN) in OMC1. The observed large circular polarization, pc0.15, can be explained by silicate grains, if their size is 0.15–1.5 μm, and they are well aligned, i.e. R > 0.5 where R is the Rayleigh reduction factor. If the grains are composed of silicates and ices, our model predicts that the degree of circular polarization pc decreases in the 3 μm ice feature, while that of linear polarization increases. Since this wavelength dependence is different from that in a process of extinction, linear and circular polarimetry of the 3 μm ice band in SEBN should be important to investigate the details of the scattering process.
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