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arXiv 1802.02307astro-ph.SRastro-ph.GA
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年轻球状星团NGC 2173中分叉蓝离散子序列的意外探测

An unexpected detection of bifurcated blue straggler sequences in the young globular cluster NGC 2173

Chengyuan Li, Licai Deng, Richard de Grijs, Dengkai Jiang, Yu Xin

摘要:

蓝离散星在色-星等图上的分叉图案引起了人们的极大关注。这种特殊的(但罕见的)两个不同的蓝离散星序列的模式通常被解释为星团核心坍缩驱动的恒星碰撞作为一种有效的形成机制的证据。在这里,我们报告的一个分叉的蓝色离散分布在一个年轻的大麦哲伦星系团,NGC 2173的检测。由于该星团中心恒星数密度低且年龄年轻,动力学分析显示,单靠恒星碰撞无法解释观测到的蓝离散星。因此,双星演化是这些蓝色离散星起源的最可行的解释。然而,为什么双星演化会使蓝掉队星的色-星等分布分叉的原因仍然不清楚。

英文摘要:

Bifurcated patterns of blue straggler stars in their color--magnitude diagrams have atracted significant attention. This type of special (but rare) pattern of two distinct blue straggler sequences is commonly interpreted as evidence of cluster core-collapse-driven stellar collisions as an efficient formation mechanism. Here, we report the detection of a bifurcated blue straggler distribution in a young Large MagellanicCloud cluster, NGC 2173. Because of the cluster's low central stellar number density and its young age, dynamical analysis shows that stellar collisions alone cannot explain the observed blue straggler stars. Therefore, binary evolution is instead the most viable explanation of the origin of these blue straggler stars. However, the reason why binary evolution would render the color--magnitude distribution of blue straggler stars bifurcated remains unclear.

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