arXiv 2009.114612020-09-24astro-ph.GA

银河系中心弧中的云-云碰撞

Cloud-Cloud Collision in the Galactic Center Arc

Masato Tsuboi, Yoshimi Kitamura, Kenta Uehara, Ryosuke Miyawaki, Takahiro Tsutsumi, Atsushi Miyazaki, Makoto Miyoshi

备注：: 40 pages, 14 figures, 2 tables, accepted for publication in PASJ
DOI：: 10.1093/pasj/psaa095

摘要：

利用Nobeyama 45 m望远镜观测的C-$^{32}$-S-$J=1-0$和SiO $v=0~J=2-1$发射谱线，对人马座A分子云（SgrAMC）中的云-云碰撞（CCC）点进行了搜索。我们在银河系中心弧（GCA）中发现了大量的冲击分子气体。其中一个M0.014-0.054位于我们以前的ALMA镶嵌观测的映射区域。我们研究了M0.014-0.054在C $^{32}$ S $J=2-1$、C $^{34}$ S $J=2-1$、SiO $v=0~J=2-1$、H $^{13}$ CO $^+ J=1-0$和SO $N,J=2,2-1,1$发射线和较暗发射线中的结构和运动学。M0.014-0.054很可能是由GCA的垂直分子细丝（VP）和沿银河经度的其他分子细丝之间的CCC形成的。在PV图上发现了这些碰撞细丝之间的桥接特征，这是CCC位点所期望的特征。我们还发现了连续致密的物体在M0.014-0.054，没有对应的H42 $α$复合线。它们在SO发射线中被检测到，并且将是“热分子核心（HMC）“。因为一个HMC的LTE质量大于维里质量，所以它被引力束缚。这也在CCS排放线中检测到。嵌入其中的恒星太年轻，无法覆盖周围的分子云。VP是由极向磁场跟踪。由于使用CF方法估计磁场强度为$\sim m$高斯，因此支持VP防止碎裂。M0.014-0.054的HMC中的恒星形成可能是由稳定丝之间的CCC诱导的，这可能是SgrAMC中的共同机制。

英文摘要：

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 C$^{32}$S $J=1-0$ and SiO $v=0~J=2-1$ emission lines. We found candidates being 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 C$^{32}$S $J=2-1$, C$^{34}$S $J=2-1$, SiO $v=0~J=2-1$, H$^{13}$CO$^+ J=1-0$, 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 (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 H42$α$ recombination line. They are detected in the SO emission line, and would be "Hot Molecular Core (HMC)"s. Because the LTE 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 poloidal magnetic field. Because the strength of the magnetic field is estimated to be $\sim m$Gauss using the CF 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.

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