Cluster formation in the W 40 and Serpens South complex triggered by the expanding H ii region
Cluster formation in the W 40 and Serpens South complex triggered by the expanding H ii region
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DOI：
10.1093/pasj/psy115
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发表时间：
2018-09
影响因子：
2.3
通讯作者：
T. Shimoikura;K. Dobashi;F. Nakamura;Y. Shimajiri;K. Sugitani
中科院分区：
文献类型：
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作者：
T. Shimoikura;K. Dobashi;F. Nakamura;Y. Shimajiri;K. Sugitani
本文介绍了利用45 m野边山射电望远镜对W 40和巨蛇座南附近1平方度范围内的12 CO（J = 1 - 0）、13 CO（J = 1 - 0）、C18 O（J = 1 -0）、CCS（JN = 87-76）和N2 H+（J = 1-0）发射谱线进行测绘观测的结果。W 40是一个红的H ii区，而巨蛇座南部是一个伴随着年轻星团的红外暗云。这两个区域在天空中相隔20英尺，到目前为止还无法识别。我们发现C18 O的排放是平稳地分布在整个W 40和巨蛇座南部地区，这两个地区似乎是物理连接。我们将C18 O的辐射在H ii区域的空间分布分为4组，根据它们的典型LSR速度，我们称之为5，6，7和8 km s-1分量，并提出了W 40和Serpens South复合体的三维模型。在位置-速度图中我们发现了两个椭圆结构，这可以解释为两个膨胀壳的一部分。其中一个壳是恰好围绕H ii区域的小内壳，另一个壳是对应于H ii区域边界的大外壳。与巨蛇座南部年轻星团相关的致密气体可能位于外壳的表面，表明年轻星团的纳塔尔星团与外壳相互作用，被外壳的膨胀压缩。我们认为壳层的膨胀导致了年轻团簇的形成。
We present the results of mapping observations covering a large area of 1 square degree around W 40 and Serpens South carried out in the 12CO (J = 1–0), 13CO (J = 1–0), C18O (J = 1–0), CCS (JN = 87–76), and N2H+ (J = 1–0) emission lines with the 45 m Nobeyama Radio Telescope. W 40 is a blistered H ii region, and Serpens South is an infrared dark cloud accompanied by a young cluster. The relation between these two regions, which are separated by ∼20′ on the sky, has not been recognizable so far. We found the C18O emission is distributed smoothly throughout the W 40 and Serpens South regions, and that the two regions seem to be physically connected. We divided the C18O emission into four groups in terms of the spatial distributions around the H ii region which we call 5, 6, 7, and 8 km s−1 components according to their typical LSR velocity, and propose a three-dimensional model of the W 40 and Serpens South complex. We found two elliptical structures in the position–velocity diagrams, which can be explained as part of two expanding shells. One of the shells is small inner shell just around the H ii region, and the other is a large outer shell corresponding to the boundary of the H ii region. Dense gas associated with the young cluster of Serpens South is likely to be located at the surface of the outer shell, indicating that the natal clump of the young cluster is interacting with the outer shell being compressed by the expansion of the shell. We suggest that the expansion of the shell induced the formation of the young cluster.