The Role of Magnetic Fields in Triggered Star Formation of RCW 120
The Role of Magnetic Fields in Triggered Star Formation of RCW 120
复制标题
磁场在 RCW 120 触发恒星形成中的作用
DOI：
10.1088/1674-4527/ac6f4c
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发表时间：
2022-04
影响因子：
1.8
通讯作者：
Yin Jia
中科院分区：
文献类型：
--
作者：
Chen Zhiwei;Sefako Ramotholo;Yang Yang;Jiang Zhibo;Yu Shuling;Yin Jia
我们报告的近红外偏振观测RCW 120与1.4米IRSF望远镜。背景恒星的星光偏振首次揭示了RCW 120的磁场。RCW 120的全球磁场是沿着20 ^circ $的方向，平行于银河平面。天空平面上的场强为100 pm26，μ G。东壳周围的磁场显示了HII区域压缩的证据。外部压力（湍流压力+磁压力）和周围云的气体密度沿RCW 120破裂的方向沿着最小，这解释了观察到的RCW 120的伸长。RCW 120的动力学年龄取决于磁场强度，对于100 μ G的磁场强度，其动力学年龄为1.6百万年，比流体动力学估计的年龄要大。在垂直于磁场的方向上，强磁场使西壳的密度对比度大大降低。与流体动力学估计相比，强磁场通常会降低触发星星形成的效率。通过收集和坍缩机制触发的星星形成可能发生在沿着磁场的方向。核心形成效率（CFE）被发现是较高的南部和东部壳的RCW 120比在红外暗云接收很少的影响，从HII区域，这表明在CFE增加有关的触发电离反馈。
We report on the near-infrared polarimetric observations of RCW 120 with the 1.4 m IRSF telescope. The starlight polarization of the background stars reveals for the first time the magnetic field of RCW 120. The global magnetic field of RCW 120 is along the direction of $20^circ$, parallel to the Galactic plane. The field strength on the plane of the sky is $100pm26,mu$G. The magnetic field around the eastern shell shows evidence of compression by the HII region. The external pressure (turbulent pressure + magnetic pressure) and the gas density of the ambient cloud are minimum along the direction where RCW 120 breaks out, which explains the observed elongation of RCW 120. The dynamical age of RCW 120, depending on the magnetic field strength, is $sim,1.6,mathrm{Myr}$ for field strength of $100,mu$G, older than the hydrodynamic estimates. In direction perpendicular to the magnetic field, the density contrast of the western shell is greatly reduced by the strong magnetic field. The strong magnetic field in general reduces the efficiency of triggered star formation, in comparison with the hydrodynamic estimates. Triggered star formation via the collect and collapse mechanism could occur in the direction along the magnetic field. Core formation efficiency (CFE) is found to be higher in the southern and eastern shells of RCW 120 than in the infrared dark cloud receiving little influence from the HII region, suggesting increase in the CFE related to triggering from ionization feedback.