Detailed Chemical Abundances of Globular Clusters in Local Group Dwarf Galaxies
Detailed Chemical Abundances of Globular Clusters in Local Group Dwarf Galaxies
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本星系群中球状星团的详细化学丰度
DOI：
10.1051/eas/1148064
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
A. McWilliam
中科院分区：
文献类型：
--
作者：
J. E. Colucci;R. Bernstein;A. McWilliam
本文给出了5个本群矮星系NGC 205、NGC 6822、WLM、SMC和LMC中17个球状星团Fe、Ca和Ba的详细化学丰度。这些丰度是在这些星系中使用高分辨率，集成光谱的新分析方法在GC中测量的20多种单个元素的更大样本的一部分。我们的分析还提供了年龄和恒星人口的限制。在不同年龄的矮星系中存在GC意味着在这些星系的整个历史中有快速星星形成（SF）的事件;这些星系团的丰度比表明这些爆发的持续时间从星系到星系有很大的不同。我们发现进化的Fe，Ca和Ba随着年龄的LMC，SMC，和NGC 6822是一致的扩展，低效率的SF之间的爆发，与低金属含量的AGB喷出物在晚些时候的贡献越来越大。我们在NGC 205和WLM中的GC样本主要是老的和贫金属的，具有高[Ca/Fe]比，这意味着这些星系的早期历史以一贯的高SF率为标志。
We present detailed chemical abundances of Fe, Ca and Ba for 17 globular clusters (GCs) in 5 Local Group dwarf galaxies: NGC 205, NGC 6822, WLM, the SMC and LMC. These abundances are part of a larger sample of over 20 individual elements measured in GCs in these galaxies using a new analysis method for high resolution, integrated light spectra. Our analysis also provides age and stellar population constraints. The existence of GCs in dwarf galaxies with a range of ages implies that there were episodes of rapid star formation (SF) throughout the history of these galaxies; the abundance ratios of these clusters suggest that the duration of these burst varied considerably from galaxy to galaxy. We find evolution of Fe, Ca, and Ba with age in the LMC, SMC, and NGC 6822 that is consistent with extended, lower-efficiency SF between bursts, with an increasing contribution of low-metallicity AGB ejecta at late times. Our sample of GCs in NGC 205 and WLM are predominantly old and metal-poor with high [Ca/Fe] ratios, implying that the early history of these galaxies was marked by consistently high SF rates.