High-mass binaries in the very young open cluster NGC 6231. Implication for cluster and star formation
High-mass binaries in the very young open cluster NGC 6231. Implication for cluster and star formation
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非常年轻的疏散星团 NGC 6231 中的高质量双星。对星团和恒星形成的影响
DOI：
10.1051/0004-6361:20000528
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
J. Mermilliod
中科院分区：
文献类型：
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作者：
B. García;J. Mermilliod
对非常年轻的疏散星团NGC 6231中的37颗O星和B星进行的新的径向速度观测证实了主序上部短周期光谱双星的高频率。在14颗O型恒星中，涵盖了从矮星到超巨星的所有光度等级，其中8颗是确定的双线系统，除了一颗之外，所有的周期都短于7天。在早期的B型恒星中还发现了另外几个联星。NGC 6231是一个特殊的星团，它限制了星团和双星在大范围恒星质量内形成的可能性。我们讨论的证据，基于NGC 6231和其他21个星团，共120 O型星，一个明确的二分法的多重率和结构的非常年轻的疏散星团包含O型星的功能的大质量恒星的数量。然而，我们不能回答的问题是，所观察到的特征是否来自形成过程或早期的动力学演化。
New radial-velocity observations of 37 O- and B stars in the very young open cluster NGC 6231 confirm the high frequency of short-period spectroscopic binaries on the upper main sequence. Among the 14 O-type stars, covering all luminosity classes from dwarfs to supergiants, 8 are definitively double-lined systems and all periods but one are shorter than 7 days. Several additional binaries have been detected among the early B-type stars. NGC 6231 is an exceptional cluster to constrain the scenarios of cluster- and binary-star formation over a large range of stellar masses. We discuss the evidences, based on NGC 6231 and 21 other clusters, with a total of 120 O-type stars, for a clear dichotomy in the multiplicity rate and structure of very young open clusters containing O-type stars in function of the number of massive stars. However, we cannot answer the question whether the observed characteristics result from the formation processes or from the early dynamical evolution.