Spectral matching for abundances and clustering analysis of stars on the giant branches of ω Centauri
Spectral matching for abundances and clustering analysis of stars on the giant branches of ω Centauri
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DOI：
10.1111/j.1365-2966.2012.22012.x
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发表时间：
2012-09
影响因子：
4.8
通讯作者：
J. Simpson;P. Cottrell;C. Worley
中科院分区：
文献类型：
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作者：
J. Simpson;P. Cottrell;C. Worley
我们已经确定了半人马座球状星团中221颗巨大分支恒星的恒星参数和丰度。结合光度法和低分辨率光谱法测定了温度、重力、金属丰度、[C/Fe]、[N/Fe]和[Ba/Fe]。这些丰度与先前研究人员的发现非常一致，并扩展了该星团的分析样本。基于这些丰度，采用K-means聚类分析将恒星分为四个均匀的组。这些恒星显示出预期的[C/Fe]和[N/Fe]之间的反相关性。我们研究了cn -弱/ cn -强恒星在色星等图上的分布。从色星等图上的位置选择的渐近巨星分支星几乎都是CN弱的。这与红巨星分支形成鲜明对比，红巨星分支中有大量的少数人是CN强的。结果还与星团形成和演化模型进行了比较。总的来说，本研究表明，从低分辨率光谱中可以得到统计上显著的元素和演化结论。
We have determined stellar parameters and abundances for 221 giant branch stars in the globular cluster ω Centauri. A combination of photometry and lower resolution spectroscopy was used to determine temperature, gravity, metallicity, [C/Fe], [N/Fe] and [Ba/Fe]. These abundances agree well with those found by previous researchers and expand the analysed sample of the cluster. k-means clustering analysis was used to group the stars into four homogeneous groups based upon these abundances. These stars show the expected anticorrelation between [C/Fe] and [N/Fe]. We investigated the distribution of CN-weak/CN-strong stars on the colour–magnitude diagram. Asymptotic giant branch stars, which were selected from their position on the colour–magnitude diagram, were almost all CN weak. This is in contrast to the red giant branch where a large minority were CN strong. The results were also compared with cluster formation and evolution models. Overall, this study shows that statistically significant elemental and evolutionary conclusions can be obtained from lower resolution spectroscopy.