MOLECULAR CLOUDS TOWARD RCW49 AND WESTERLUND 2: EVIDENCE FOR CLUSTER FORMATION TRIGGERED BY CLOUD–CLOUD COLLISION
MOLECULAR CLOUDS TOWARD RCW49 AND WESTERLUND 2: EVIDENCE FOR CLUSTER FORMATION TRIGGERED BY CLOUD–CLOUD COLLISION
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DOI：
10.1088/0004-637x/696/2/l115
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发表时间：
2009-04
期刊：
影响因子：
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通讯作者：
N. Furukawa;J. Dawson;A. Ohama;A. Kawamura;N. Mizuno;T. Onishi;Y. Fukui
中科院分区：
文献类型：
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作者：
N. Furukawa;J. Dawson;A. Ohama;A. Kawamura;N. Mizuno;T. Onishi;Y. Fukui
我们用NANTEN 2亚毫米波望远镜对RCW 49的H ii区及其电离源-富星团Westerlund 2进行了CO（J = 2-1）观测。这些观测显示，两个速度范围分别为-11至+9 km s-1和11至21 km s-1的分子云与斯皮策IRAC RCW 49的中红外图像显示出非常好的空间相关性，以及指示明亮中心区域和星团周围局部膨胀的速度结构。这强烈表明这两个云在物理上与RCW 49有关。根据伴生气的平均速度和速度分布，我们得到了RCW 49和Wd 2的新的运动学距离估计为5.4+1.1−1.4 kpc。我们认为，气体加速恒星风从韦斯特隆德2是不足以解释整个观察到的速度分散的分子气体，并提出了一个方案，其中两个云之间的碰撞可能引发了恒星团的形成1400万年前。
We have made CO(J = 2–1) observations toward the H ii region RCW 49 and its ionizing source, the rich stellar cluster Westerlund 2, with the NANTEN2 submillimeter telescope. These observations have revealed that two molecular clouds in velocity ranges of −11 to +9 km s−1 and 11 to 21 km s−1, respectively, show remarkably good spatial correlations with the Spitzer IRAC mid-infrared image of RCW 49, as well a velocity structures indicative of localized expansion around the bright central regions and stellar cluster. This strongly suggests that the two clouds are physically associated with RCW 49. We obtain a new kinematic distance estimate to RCW 49 and Wd2 of 5.4+1.1−1.4 kpc, based on the mean velocity and velocity spread of the associated gas. We argue that the acceleration of the gas by stellar winds from Westerlund 2 is insufficient to explain the entire observed velocity dispersion of the molecular gas, and suggest a scenario in which a collision between the two clouds ∼4 Myr ago may have triggered the formation of the stellar cluster.