发表机构
University of Canterbury; Universidad Diego Portales; INAF–Osservatorio Astrofisico di Arcetri（坎特伯雷大学; 迭戈·波特莱斯大学; 意大利国家天体物理研究所阿切特里天文台）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用Gaia-ESO巡天光谱，通过Mg-Al反相关分析14个球状星团的恒星族群，发现反相关取决于星团质量与金属丰度，揭示了复杂化学增丰历史。
AI 中文摘要
背景。球状星团（GCs）是银河系化学历史和演化的碎片。它们显著的星团内丰度变化已被用于表征化学趋势和恒星族群。然而，这些族群的起源以及球状星团本身的起源在很大程度上仍然未知。目的。我们的目标是利用从Gaia-ESO巡天（GES）光谱中推导出的丰度，探索属于14个球状星团的恒星族群的起源。特别是，我们使用Mg-Al反相关来区分这些族群。方法。重新审视了GES光谱，以推导出额外的均匀的Mg和Al化学丰度。对每个星团的[Mg/Al]分布应用了高斯混合模型（GMM），以定义两个主要族群之间的阈值。结果。八个星团暗示存在Mg-Al反相关和双族群。我们发现，在[Fe/H]约为-1.4附近存在一个状态转变，在更高的金属丰度下，Mg-Al反相关消失。几个星团，无论其Mg-Al反相关行为如何，都表现出金属丰度扩散（例如，NGC 2808，NGC 6752）和s过程变化（例如，NGC 7078，NGC 1851），这表明了复杂的增丰历史。结论。Mg-Al反相关的存在和扩散取决于星团的质量和金属丰度，其中贫金属和/或大质量星团表现出最清晰的反相关。这项工作展示了可以从Gaia-ESO巡天光谱中检索到的额外丰度，并进一步深入了解了球状星团内多个恒星族群的化学特性。这些发现突显了球状星团的化学复杂性，以及需要大型、均匀的数据集来追踪它们的形成历史。
英文摘要
Context. Globular clusters (GCs) are fragments of the chemical history and evolution of the Milky Way. Their notable intra-cluster abundance variations have been used to characterise chemical trends and stellar populations. However, the origins of these populations and GCs in general are still largely unknown. Aims. Our aim is to explore the origin of the stellar populations belonging to 14 GCs making use of their abundances derived from the Gaia-ESO Survey (GES) spectra. In particular, we use the Mg-Al anti-correlation to separate the populations. Methods. The GES spectra were revisited to derive additional homogenous chemical abundances for Mg and Al. A Gaussian Mixture Model (GMM) was applied to the [Mg/Al] distribution for each cluster to define a threshold between the two main populations. Results. Eight clusters imply the presence of Mg-Al anti-correlations and dual populations. We find there is a regime transition near [Fe/H] approximately -1.4, where, the Mg-Al anti-correlation disappears at higher metallicity. Several clusters, regardless of their Mg-Al anti- correlation behaviour, exhibit metallicity spreads (e.g., NGC 2808, NGC 6752) and s-process variations (e.g., NGC 7078, NGC 1851), suggesting complex enrichment histories. Conclusions. The presence and spread of the Mg-Al anti-correlation depend on cluster mass and metallicity, with metal poor and/or massive clusters exhibiting the clearest anti-correlation. This work demonstrates additional abundances that can be retrieved from Gaia-ESO Survey spectra and provides further insight into the chemistry of multiple stellar populations within GCs. These findings highlight the chemical complexity of GCs and the need for large, homogeneous datasets to trace their formation histories.
CommentsSubmitted. 15 pages. 8 figures. 4 tables
