arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1111.6068astro-ph.GAastro-ph.CO
收藏

高分辨率积分光光谱学的球状星团丰度。IV。大麦云：$α$、Fe峰、轻元素和重元素

Globular Cluster Abundances from High-Resolution, Integrated-Light Spectroscopy. IV. The Large Magellanic Cloud: $α$, Fe-peak, Light, and Heavy Elements

J. E. Colucci, R. A. Bernstein, S. A. Cameron, A. McWilliam

备注：
38 pages, Accepted for publication in the Astrophysical Journal
阅读 PDF
arXiv 页面 ↗HTML 原文 ↗

摘要：

本文详细介绍了大麦云（LMC）中8个星团的化学丰度。我们测量了年龄在0.05至12 Gyr范围内的22种元素的丰度，为LMC的化学富集和恒星形成历史提供了全面的图像。这些丰度是用一种新的方法从星团的高分辨率（$R\sim$ 25，000）积分光谱的单个吸收线中获得的。该方法在本系列的第一、二和三篇论文中得到了发展和介绍。在本文中，我们开发了一个额外的集成光$χ^2$最小化光谱合成技术，以方便测量弱（$\sim$ 15毫微微）光谱线和丰度低信噪比数据（S/N $\sim$ 30）。此外，我们补充了详细的丰度，我们在我们的样本中测量的最年轻的集群（年龄$<$ 2 Gyr）的个别恒星的综合光丰度测量。在积分光丰度和恒星丰度中，我们发现[ $α$ /Fe]随[Fe/H]和年龄的演化。铁峰丰度比与银河系中的相似，除了[Cu/Fe]和[Mn/Fe]，它们在高金属丰度时位于太阳下。Ba、La、Nd、Sm和Eu等重元素在最年轻的团簇中明显增强。此外，重，轻的s-过程的比率是升高相对于银河系（[Ba/Y] $>+0.5$），并随着年龄的减少而增加，表明低金属AGB恒星喷出物的星际介质的整个LMC的后期历史的强大贡献。我们还发现了一个相关的综合轻钠和铝丰度与集群质量，在这个意义上说，更大的质量，更老的集群富集轻元素钠和铝相对于铁，这意味着这些集群港口恒星到恒星的丰度变化是常见的银河系。

英文摘要：

We present detailed chemical abundances in 8 clusters in the Large Magellanic Cloud (LMC). We measure abundances of 22 elements for clusters spanning a range in age of 0.05 to 12 Gyr, providing a comprehensive picture of the chemical enrichment and star formation history of the LMC. The abundances were obtained from individual absorption lines using a new method for analysis of high resolution ($R\sim$25,000) integrated light spectra of star clusters. This method was developed and presented in Papers I, II, and III of this series. In this paper, we develop an additional integrated light $χ^2$-minimization spectral synthesis technique to facilitate measurement of weak ($\sim$15 mÅ) spectral lines and abundances in low signal-to-noise ratio data (S/N$\sim$30). Additionally, we supplement the integrated light abundance measurements with detailed abundances that we measure for individual stars in the youngest clusters (Age$<$2 Gyr) in our sample. In both the integrated light and stellar abundances we find evolution of [$α$/Fe] with [Fe/H] and age. Fe-peak abundance ratios are similar to those in the Milky Way, with the exception of [Cu/Fe] and [Mn/Fe], which are sub-solar at high metallicities. The heavy elements Ba, La, Nd, Sm, and Eu are significantly enhanced in the youngest clusters. Also, the heavy to light s-process ratio is elevated relative to the Milky Way ([Ba/Y]$>+0.5$) and increases with decreasing age, indicating a strong contribution of low-metallicity AGB star ejecta to the interstellar medium throughout the later history of the LMC. We also find a correlation of integrated light Na and Al abundances with cluster mass, in the sense that more massive, older clusters are enriched in the light elements Na and Al with respect to Fe, which implies that these clusters harbor star-to-star abundance variations as is common in the Milky Way.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

↑