Physical modelling of dust polarization from magnetically enhanced radiative torque alignment in protostellar cores withpolaris

Author:

Giang Nguyen Chau12ORCID,Hoang Thiem12,Kim Jeong-Gyu23,Tram Le Ngoc4

Affiliation:

1. Korea Astronomy and Space Science Institute , Daejeon 34055, Republic of Korea

2. Korea University of Science and Technology , 217 Gajeong-ro, Yuseong-gu, Daejeon 34113, Republic of Korea

3. National Astronomical Observatory of Japan, National Institutes of Natural Sciences , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan

4. Max-Planck-Institut für Radioastronomie , Auf dem Hügel 69, 53-121 Bonn, Germany

Abstract

ABSTRACTMagnetic fields (B) are an important factor controlling the star-formation process. The leading method to observe B orientation is to use polarized thermal emission from aligned dust grains. In dense environments such as protostellar cores, however, dust grains may be inefficiently aligned owing to strong gas randomizations, making the use of dust polarization to trace Buncertain. The study of Hoang and Lazarian in 2016 demonstrated that grain alignment by radiative torques is enhanced if dust grains contain embedded iron inclusions. Here we extend the polaris code to study the effect of iron inclusions on grain alignment and thermal dust polarization towards a protostellar core, assuming uniform B. We found that paramagnetic grains produce a low polarization degree of $p \sim 1{{\ \rm per\ cent}}$ in the envelope and a negligible $p \ll 1{{\ \rm per\ cent}}$ in the central region owing to the loss of grain alignment. In contrast, grains with a high level of iron inclusions have perfect alignment and produce a high $p \sim 40{{\ \rm per\ cent}}$ in the envelope and a low $p \le 10{{\ \rm per\ cent}}$ in the central region. Grains with a moderate level of iron inclusions induce the polarization flipping from P ‖ B at millimetre to P ⊥ B at submillimetre wavelengths owing to the change in the internal alignment caused by slow internal relaxation. The weak alignment of very large grains with $a \ge 10\, {\mu \rm {m}}$ reduces dichroic extinction efficiency at submillimetre wavelengths. We found a positive correlation between p and the level of iron inclusions, which introduces a new option to constrain the abundance of solid iron locked in dust through dust polarimetry.

Funder

National Research Foundation of Korea

Publisher

Oxford University Press (OUP)

Subject

Space and Planetary Science,Astronomy and Astrophysics

Cited by 10 articles. 订阅此论文施引文献 订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献

同舟云学术

1.学者识别学者识别

2.学术分析学术分析

3.人才评估人才评估

"同舟云学术"是以全球学者为主线,采集、加工和组织学术论文而形成的新型学术文献查询和分析系统,可以对全球学者进行文献检索和人才价值评估。用户可以通过关注某些学科领域的顶尖人物而持续追踪该领域的学科进展和研究前沿。经过近期的数据扩容,当前同舟云学术共收录了国内外主流学术期刊6万余种,收集的期刊论文及会议论文总量共计约1.5亿篇,并以每天添加12000余篇中外论文的速度递增。我们也可以为用户提供个性化、定制化的学者数据。欢迎来电咨询!咨询电话:010-8811{复制后删除}0370

www.globalauthorid.com

TOP

Copyright © 2019-2024 北京同舟云网络信息技术有限公司
京公网安备11010802033243号  京ICP备18003416号-3