EXTENDED STAR FORMATION IN THE INTERMEDIATE-AGE LARGE MAGELLANIC CLOUD STAR CLUSTER NGC 2209
EXTENDED STAR FORMATION IN THE INTERMEDIATE-AGE LARGE MAGELLANIC CLOUD STAR CLUSTER NGC 2209
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DOI：
10.1088/2041-8205/761/1/l5
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发表时间：
2012-12
期刊：
影响因子：
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通讯作者：
S. Keller;A. Mackey;G. D. Da Costa
中科院分区：
文献类型：
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作者：
S. Keller;A. Mackey;G. D. Da Costa
本文介绍了用双子座南望远镜GMOS成像仪对大麦哲伦星云中1 Gyr年龄的星星团NGC 2209的观测结果。这些观测结果表明，该星团的主序星的亮度变化范围比单一年龄的恒星群所能解释的范围更广。这使得NGC 2209成为越来越多的中等年龄（1-3 Gyr）的星团之一，这些星团显示出星星形成的扩展或多个时代的证据，其范围在5000万年到4.6亿年之间。在NGC 2209中观测到的主序的延长关闭证实了Keller等人基于星系团的大核心半径所做的预测。我们认为次级星星的形成是大质量星星团演化的一个决定性特征。低质量的星团通过蒸发的结果，只有经历了二级星星形成的集群生存的哈勃时间，从而提供了一个自然的连接之间的扩展的主序星关闭现象和无处不在的轻元素丰度范围内看到的古老的银河系球状星团。
We present observations of the 1 Gyr old star cluster NGC 2209 in the Large Magellanic Cloud made with the GMOS imager on the Gemini South Telescope. These observations show that the cluster exhibits a main-sequence turnoff that spans a broader range in luminosity than can be explained by a single-aged stellar population. This places NGC 2209 amongst a growing list of intermediate-age (1–3 Gyr) clusters that show evidence for extended or multiple epochs of star formation of between 50 and 460 Myr in extent. The extended main-sequence turnoff observed in NGC 2209 is a confirmation of the prediction in Keller et al. made on the basis of the cluster's large core radius. We propose that secondary star formation is a defining feature of the evolution of massive star clusters. Dissolution of lower mass clusters through evaporation results in only clusters that have experienced secondary star formation surviving for a Hubble time, thus providing a natural connection between the extended main-sequence turnoff phenomenon and the ubiquitous light-element abundance ranges seen in the ancient Galactic globular clusters.