Formation of high-mass stars in an isolated environment in the Large Magellanic Cloud
Formation of high-mass stars in an isolated environment in the Large Magellanic Cloud
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DOI：
10.1093/pasj/psz011
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发表时间：
2019-01
影响因子：
2.3
通讯作者：
R. Harada;T. Onishi;K. Tokuda;S. Zahorecz;A. Hughes;M. Meixner;M. Sewiło;R. Indebetouw;O. Nayak;Y. Fukui;K. Tachihara;K. Tsuge;A. Kawamura;K. Saigo;T. Wong;J. Bernard;I. Stephens
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文献类型：
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作者：
R. Harada;T. Onishi;K. Tokuda;S. Zahorecz;A. Hughes;M. Meixner;M. Sewiło;R. Indebetouw;O. Nayak;Y. Fukui;K. Tachihara;K. Tsuge;A. Kawamura;K. Saigo;T. Wong;J. Bernard;I. Stephens
本研究的目的是在大麦哲伦星云的孤立环境中，描述与大质量年轻恒星天体（YSO）相关的纳塔尔气体的分布和基本性质。大质量恒星通常形成于巨大的分子云（GMC）中，是年轻星团的一部分，但也有一些OB星被观测到远离GMC。通过检查NANTEN和Mopra观测到的高质量YSO和12 CO（J = 1-0）发射之间的空间重合，我们选择了1 - 0个远离任何NANTEN云但被Mopra观测到的高质量YSO。阿尔马的观测结果表明，一个质量为几千个太阳质量或更小的致密分子云与高质量的YSO有关，这表明这些致密云是高质量星星形成的场所。整个云的高密度和高温的解释是由于较低的金属丰度比在银河系中的CO的严重的光解。星星的形成效率从几个到高达40%，表明在这些环境中有效的星星形成。从气体速度信息和与低密度气体的关联判断，增强的湍流可能是其中有效形成星星的原因。
The aim of this study is to characterize the distribution and basic properties of the natal gas associated with high-mass young stellar objects (YSOs) in isolated environments in the Large Magellanic Cloud. High-mass stars usually form in giant molecular clouds (GMCs) as part of a young stellar cluster, but some OB stars are observed far from GMCs. By examining the spatial coincidence between the high-mass YSOs and 12CO (J = 1–0) emission detected by NANTEN and Mopra observations, we selected ten high-mass YSOs that are located away from any of the NANTEN clouds but are detected by the Mopra pointed observations. The ALMA observations revealed that a compact molecular cloud whose mass is a few thousand solar masses or smaller is associated with the high-mass YSOs, which indicates that these compact clouds are the sites of high-mass star formation. The high density and high temperature throughout the clouds are explained by the severe photodissociation of CO due to the lower metallicity than in the Galaxy. The star formation efficiency ranges from several to as high as ∼40%, indicating efficient star formation in these environments. The enhanced turbulence may be a cause of the efficient star formation therein, as judged from the gas velocity information and the association with the lower density gas.