贫金属球状星团NGC 4372中双峰型镁-铝反相关的线索
Hint of bimodal Mg-Al anticorrelation in the metal-poor Globular Cluster NGC 4372
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中文总结 AI 辅助
本研究通过高分辨率UVES光谱分析NGC 4372的7颗红巨星，证实其含至少两类恒星族，发现潜在双峰型镁-铝反相关，为理解银晕早期化学富集提供关键依据。
中文摘要 AI 辅助
我们基于高分辨率UVES光谱，对极贫金属球状星团NGC 4372中的7颗红巨星支恒星进行了详细的化学丰度分析，旨在表征NGC 4372的化学演化并研究其多星族的存在。我们采用等效宽度和光谱合成两种方法，推导了17种元素的丰度，包括轻元素、铁峰元素、α元素及重元素。结果显示该星团的平均金属丰度为[Fe/H]=$-$2.36±0.03 dex，无固有铁丰度弥散的证据；其α增强特征为[α/Fe]=0.33±0.05 dex，且存在明确的钠-氧反相关，证实NGC 4372至少包含两类不同的恒星族。此外，测得的[Ba/Eu]=$-$0.47±0.04比值表明重元素合成以r-过程为主，与其他极贫金属环境的情况一致。我们还识别出潜在的双峰型镁-铝反相关，这与质量和金属丰度相近的球状星团（GCs）中观测到的模式相符。这些结果进一步巩固了NGC 4372作为理解银晕早期化学富集基石的地位。
英文摘要
We present a detailed chemical abundance analysis of seven red giant branch stars in the very metal-poor globular cluster NGC~4372, based on high-resolution UVES spectra. Our study aims to characterize the chemical evolution of NGC~4372 and investigate the presence of multiple populations. We derived abundances for 17 elements, including light, iron-peak, $α$, and heavy elements, using both equivalent width and spectral synthesis methods. We find a mean cluster metallicity of [Fe/H]=$-$2.36 $\pm$ 0.03 dex, with no evidence of an intrinsic iron spread. The cluster exhibits a typical $α$-enhancement of [$α$/Fe]= 0.33 $\pm$ 0.05 dex and a well defined Na-O anticorrelation, confirming that NGC 4372 hosts at least two distinct stellar populations. Furthermore, the measured ratio of [Ba/Eu] =$-0.47 \pm 0.04$ indicates that the synthesis of heavy elements was dominated by $r$-process, consistent with other very metal-poor environments. We also identify a potential bimodal Mg-Al anticorrelation, which aligns with the patterns observed in GCs of similar mass and metallicity. These results reinforce the status of NGC 4372 as a cornerstone for understanding the early chemical enrichment of the Galactic Halo.
发表机构
- Universidad de La Serena（拉塞雷纳大学）
- Universidad Central de Chile（智利中央大学）
- Universidad Andres Bello（安德烈斯贝略大学）
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