Spectroscopy of the open cluster Blanco 1 - II. Hα emission as an indicator of relative age
Spectroscopy of the open cluster Blanco 1 - II. Hα emission as an indicator of relative age
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DOI：
10.1051/aas:1997316
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发表时间：
1997-02
期刊：
影响因子：
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通讯作者：
P. Panagi;M. A. O'dell
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文献类型：
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作者：
P. Panagi;M. A. O'dell
给出了年轻疏散星团布兰科1中114颗低质量恒星的H（6562 A）和Li i（6708 A）观测结果。我们还给出了Ca ii（K）中30颗恒星的观测结果。这项工作扩展了Panagi等（1994）的第一个布兰科1光谱研究。从包括布兰科1在内的四个已被充分研究的星团的样本中，我们发现，H型发射线恒星在K型矮星中所占的比例是相对年龄的一个很好的指标，较小的比例表明年龄较大。布兰科1显示了一个相对较小的部分发射，不符合以前的年龄估计的集群。我们估计星团的年龄为90 - 25百万年，比昂宿星团稍老。该方法被证明是更敏感的年龄比锂和一个有用的替代其他年龄测量技术。H随（B V）的变化与在较老的太阳邻域矮星中观察到的相似，这表明至少对于吸收线恒星，恒星自转对等效宽度的贡献是不清楚的。我们联合收割机结合光谱学和光度学来修正星团成员，并给出所有这些恒星的精确位置。
We present the results of H(6562 A) and Li i(6708 A) observations of 114 low-mass stars of the young open cluster Blanco 1. We also present observa- tions of 30 stars in Ca ii(K). This work extends the rst Blanco 1 spectroscopic study of Panagi et al. (1994). From a sample of four well-studied clusters, including Blanco 1, we nd that the fraction of H emission-line stars amongst K dwarfs is a good indicator of relative age, with a smaller fraction indicative of older age. Blanco 1 shows a relatively small fraction of emitters, inconsistent with previous age estimates for the cluster. We estimate the cluster age to to be 90 25 Myr, slightly older than the Pleiades. The method is shown to be more sensitive to age than lithium and a useful alternative to other age measurement techniques. The variation of H with (B V ) is similar to that ob- served in the older solar neighbourhood dwarfs, suggesting that, at least for the absorption-line stars, the contribu- tion of stellar rotation to the equivalent width is unclear. We combine both spectroscopy and photometry to re- vise cluster membership and give accurate positions for all these stars.