结合FAST与JCMT测量分子云磁场的三维结构

Interstellar magnetic field is one of the most important physical quantities regulating the process of star formation in molecular clouds. To date, the two most practical methods of measuring magnetic fields in molecular clouds are the Zeeman observations to reveal the field strength along the line of sight and polarization observations of dust continuum emission at radio wavelengths to reveal the 2-dimensional field structure on the plane of the sky. However, few clouds have been measured with both of the methods, and our understanding of interstellar magnetic fields is not yet comprehensive. We propose to build the 3-dimensional magnetic field structure in molecular clouds with the combination of the FAST HI Narrow Self-Absorption (HINSA) line and OH Zeeman observations and the JCMT dust polarization observations. The combined results will give a more accurate estimation of the total magnetic field strength at the critical density in molecular clouds, revealing the evolution of magnetic fields in the process of star formation. This project may become the first detection of HINSA Zeeman observations, offering an important result for studying interstellar magnetic fields and star formation. We have carried out polarization commissioning and HINSA observations of FAST and obtained the newest dust polarization observations of JCMT, indicating the high feasibility of this project.

星际磁场是决定分子云如何形成恒星最重要的物理量之一。目前测量分子云磁场的主要手段是以塞曼效应测量视线方向上的磁场强度与以星际尘埃的无线电连续谱偏振测量天空平面上磁场的二维结构。由于只有少数的分子云同时有此两种方法观测磁场的结果，目前缺少对星际磁场完整的研究。本项目计划结合FAST中性氢窄线自吸收与OH分子的塞曼效应观测与JCMT的星际尘埃偏振观测来建构分子云中磁场的三维结构，以准确的测量分子云内磁场的总强度与临界密度并揭示星际磁场在分子云内的演化的过程。本项目有望成为首次中性氢窄线自吸收塞曼效应的观测结果，提供星际磁场与恒星形成不可或缺的研究。我们已进行FAST偏振调试及中性氢窄线自吸收观测的相关工作，并获得了JCMT星际尘埃偏振观测的最新数据，显示了本项目的高度可行性。

星际磁场是决定恒星形成过程最重要的物理量之一。目前测量分子云磁场的主要手段是以塞曼效应测量视线方向的磁场和以星际尘埃的无线电连续谱偏振测量磁场在天空平面的分量。得益于FAST望远镜领先世界的灵敏度，本项目首次获得了中性氢窄线自吸收的塞曼效应成果。FAST的结果显示分子云比标准模型超前达到超临界状态，可能存在比双极扩散更有效的耗散机制，为回答恒星形成经典三大难题之一的磁流量问题提供了重要的观测依据。本成果的论文已发表为<<自然>>期刊2022年首刊的封面文章。本项目也使用JCMT望远镜的无线电连续谱偏振测量星际磁场，揭示了大质量恒星形成区DR21与金牛座分子云的磁场结构。我们未来会系统性的结合HINSA的塞曼效应与星际尘埃偏振观测以推进星际磁场的分析和研究。

内容获取失败，请点击重试