Cloud-cloud collision in the Galactic Center Arc
Cloud-cloud collision in the Galactic Center Arc
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银河中心弧内的云与云碰撞
DOI：
10.1093/pasj/psaa095
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发表时间：
2021
影响因子：
2.3
通讯作者：
Miyoshi Makoto
中科院分区：
文献类型：
--
作者：
Tsuboi Masato;Kitamura Yoshimi;Uehara Kenta;Miyawaki Ryosuke;Tsutsumi Takahiro;Miyazaki Atsushi;Miyoshi Makoto
我们根据使用 Nobeyama 45 m 望远镜在 C32S J = 1-0 和 SiO v = 0 J = 2-1 发射线中的调查观测，对人马座 A 分子云 (SgrAMC) 中的云-云碰撞 (CCC) 位置进行了搜索。我们在银河中心弧（GCA）中发现了富含冲击分子气体的候选者。其中之一，M0.014−0.054，位于我们之前 ALMA 马赛克观测的绘图区域。我们探索了 C32S J = 2–1、C34S J = 2–1、SiO v = 0 J = 2–1、H13CO+J = 1–0 和 SO N, J = 2, 2–1, 1 发射线和较弱发射线中 M0.014−0.054 的结构和运动学。 M0.014−0.054 可能是由 GCA 的垂直分子丝（“垂直部分”或 VP）与沿银河经度的其他分子丝之间的 CCC 形成的。在 PV 图上发现了这些碰撞灯丝之间的桥接特征，这是 CCC 站点中预期的特征。我们还在 M0.014−0.054 中发现了连续致密天体，它们在 H42α 重组线中没有对应物。它们在 SO 排放线中被检测到，并且将是“热分子核心”（HMC）。由于一种 HMC 的局部热力学平衡质量大于维里质量，因此它受到引力束缚。这也在 CCS 排放线中检测到。嵌入的恒星太年轻，无法电离周围的分子云。 VP 由极向磁场追踪。由于使用钱德拉塞卡-费米方法估计磁场强度为 ∼mgauss，因此支持 VP 防止碎裂。 M0.014−0.054 HMC 中的星形形成可能是由稳定丝之间的 CCC 诱导的，这可能是 SgrAMC 中的常见机制。
We performed a search of cloud–cloud collision (CCC) sites in the Sagittarius A molecular cloud (SgrAMC) based on the survey observations using the Nobeyama 45 m telescope in the C32S J = 1–0 and SiO v = 0 J = 2–1 emission lines. We found candidates abundant in shocked molecular gas in the Galactic Center Arc (GCA). One of them, M0.014−0.054, is located in the mapping area of our previous ALMA mosaic observation. We explored the structure and kinematics of M0.014−0.054 in the C32S J = 2–1, C34S J = 2–1, SiO v = 0 J = 2–1, H13CO+J = 1–0, and SO N, J = 2, 2–1, 1 emission lines and fainter emission lines. M0.014−0.054 is likely formed by the CCC between the vertical molecular filaments (the “vertical part,” or VP) of the GCA, and other molecular filaments along Galactic longitude. The bridging features between these colliding filaments on the PV diagram are found, which are the characteristics expected in CCC sites. We also found continuum compact objects in M0.014−0.054, which have no counterpart in the H42α recombination line. They are detected in the SO emission line, and would be “hot molecular cores” (HMCs). Because the local thermodynamic equilibrium mass of one HMC is larger than the virial mass, it is bound gravitationally. This is also detected in the CCS emission line. The embedded star would be too young to ionize the surrounding molecular cloud. The VP is traced by a poloidal magnetic field. Because the strength of the magnetic field is estimated to be ∼mgauss using the Chandrasekhar–Fermi method, the VP is supported against fragmentation. The star formation in the HMC of M0.014−0.054 is likely induced by the CCC between the stable filaments, which may be a common mechanism in the SgrAMC.