Scattering Polarization of 3 μm Water-ice Feature by Large Icy Grains
Abstract
Water ice has a strong spectral feature at a wavelength of approximately 3 μm, which plays a vital role in our understanding of the icy universe. In this study, we investigate the scattering polarization of this water-ice feature. The linear polarization degree of light scattered by micron-sized icy grains is known to be enhanced at the ice band; however, the dependence of this polarization enhancement on various grain properties is unclear. We find that the enhanced polarization at the ice band is sensitive to the presence of micron-sized grains as well as their ice abundance. We demonstrate that this enhancement is caused by the high absorbency of the water-ice feature, which attenuates internal scattering and renders the surface reflection dominant over internal scattering. Additionally, we compare our models with polarimetric observations of the low-mass protostar L1551 IRS 5. Our results show that scattering by a maximum grain radius of a few microns with a low water-ice abundance is consistent with observations. Thus, scattering polarization of the water-ice feature is a useful tool for characterizing ice properties in various astronomical environments.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2021
- DOI:
- 10.3847/1538-4357/abdd3d
- arXiv:
- arXiv:2101.07635
- Bibcode:
- 2021ApJ...910...26T
- Keywords:
-
- Circumstellar dust;
- Spectropolarimetry;
- Ice destruction;
- Near infrared astronomy;
- 236;
- 1973;
- 2091;
- 1093;
- Astrophysics - Astrophysics of Galaxies;
- Astrophysics - Earth and Planetary Astrophysics;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 19 pages, 17 figures, 1 table