Another cluster of red supergiants close to RSGC1
Another cluster of red supergiants close to RSGC1
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DOI：
10.1051/0004-6361/200913373
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发表时间：
2010-02
影响因子：
6.5
通讯作者：
I. Negueruela;C. Gonzalez-Fernandez;A. Marco;J. Clark;S. Martínez-Núñez
中科院分区：
文献类型：
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作者：
I. Negueruela;C. Gonzalez-Fernandez;A. Marco;J. Clark;S. Martínez-Núñez
上下文最近的研究揭示了银河系靠近长棒尖端的一个区域中存在着巨大的星星团。这些星团被严重遮蔽，其特征是红超巨星的数量。目标。我们分析了一个以前没有报道过的明亮的红色恒星的浓度，距离星团RSGC1方法。我们利用近红外光度法来确定候选的红超巨星，然后利用样品的K带光谱来确定它们的性质。结果我们发现了一个由八颗红超巨星和五颗其他候选者组成的紧凑星团，其中一颗被光谱证实为红超巨星。这些天体一定形成了一个疏散星团，我们将其命名为阿利坎特8。由于高度红化和强场污染，在2MASS或UKIDSS近红外测光中无法清楚地看到团簇序列。根据对红超巨星的分析，我们推断灭绝的AKS = 1.9，年龄接近2000万年。结论.虽然这个星系团比以前已知的三个星系团要小，但它的性质仍然表明它的质量超过10000 M ²。它的发现证实了一个假设，即该地区的星星形成发生在2.1亿至2.2亿年前。
Context. Recent studies have revealed massive star clusters in a region of the Milky Way close to the tip of the Long Bar. These clusters are heavily obscured and are characterised by a population of red supergiants. Aims. We analyse a previously unreported concentration of bright red stars ∼16 � away from the cluster RSGC1 Methods. We utilised near IR photometry to identify candidate red supergiants and then K-band spectroscopy of a sample to characterise their properties. Results. We find a compact clump of eight red supergiants and five other candidates at some distance, one of which is spectroscopically confirmed as a red supergiant. These objects must form an open cluster, which we name Alicante 8. Because of the high reddening and strong field contamination, the cluster sequence is not clearly seen in 2MASS or UKIDSS near-IR photometry. From the analysis of the red supergiants, we infer an extinction AKS = 1.9 and an age close to 20 Myr. Conclusions. Though this cluster is smaller than the three known previously, its properties still suggest a mass in excess of 10 000 M� . Its discovery corroborates the hypothesis that star formation in this region has happened on a wide scale between ∼10 and ∼20 Myr ago.