High-mass star formation in Orion possibly triggered by cloud?cloud collision. III. NGC 2068 and NGC 2071
High-mass star formation in Orion possibly triggered by cloud?cloud collision. III. NGC 2068 and NGC 2071
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猎户座的大质量恒星形成可能是由云与云的碰撞引发的。
DOI：
10.1093/pasj/psaa005
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发表时间：
2020
影响因子：
2.3
通讯作者：
Fukui Yasuo
中科院分区：
文献类型：
--
作者：
Fujita Shinji;Tsutsumi Daichi;Ohama Akio;Habe Asao;Sakre Nirmit;Okawa Kazuki;Kohno Mikito;Hattori Yusuke;Nishimura Atsushi;Torii Kazufumi;Sano Hidetoshi;Tachihara Kengo;Kimura Kimihiro;Ogawa Hideo;Fukui Yasuo
利用NANTEN 2天文台，我们对猎户座中具有反射星云的大质量星星形成区NGC 2068和NGC 2071进行了CO（-1）跃迁的分子谱线研究。CO的分布表明，在和kms处有两个速度分量.蓝移的分量位于东北，与NGC 2071有关，而红移的分量则位于西南，与NGC 2068有关。两个云团的总强度分布有个pc的差距，表明它们目前是分离的。详细的空间比较表明，两者表现出互补的分布。蓝移分量位于红移分量西北方向的强度低压区，在那里，我们发现位移为pc使得两个云很好地吻合。此外，一个新的模拟非锋面碰撞表明，观测fromoff碰撞轴同意在这一地区的速度结构。根据这些结果，我们假设这两个组件相互碰撞的投影相对速度为公里。碰撞的时间尺度估计为百万年为一个假设的轴的相对motionoff视线。我们假设云中两颗质量最大的早期B型恒星，照亮了两个反射星云的恒星，是由两个云之间界面的碰撞触发形成的。考虑到其他年轻的高质量恒星形成区，即M 42，M 43和NGC 2024（福井等人）。a，ApJ，859，166; Ohama et al.，arXiv：1706.05652），在最后一个百万年里，碰撞触发似乎独立地在猎户座中形成了O型和早期B型恒星，预计距离为100万秒差距。
Using the NANTEN2 Observatory, we carried out a molecular-line study of high-mass star forming regions with reflection nebulae, NGC 2068 and NGC 2071, in Orion in theCO(–1) transition. TheCO distribution shows that there are two velocity components atandkms. The blue-shifted component is in the northeast associated with NGC 2071, whereas the red-shifted component is in the southwest associated with NGC 2068. The total intensity distribution of the two clouds shows a gap ofpc, suggesting that they are detached at present. A detailed spatial comparison indicates that the two show complementary distributions. The blue-shifted component lies toward an intensity depression to the northwest of the red-shifted component, where we find that a displacement ofpc makes the two clouds fit well with each other. Furthermore, a new simulation of non-frontal collisions shows that observations fromoff the collisional axis agreed well with the velocity structure in this region. On the basis of these results, we hypothesize that the two components collided with each other at a projected relative velocity ofkms. The timescale of the collision is estimated to beMyr for an assumed axis of the relative motionoff the line of sight. We assume that the two most massive early B-type stars in the cloud, illuminating stars of the two reflection nebulae, were formed by collisional triggering at the interfaces between the two clouds. Given the other young high-mass star-forming regions, namely, M 42, M 43, and NGC 2024 (Fukui et al. a, ApJ, 859, 166; Ohama et al. , arXiv: 1706.05652), it seems possible that collisional triggering has been independently working to form O-type and early B-type stars in Orion in the last Myr over a projected distance of ∼80 pc.