发表机构
University of California, Los Angeles; Lund University; Université Côte d’Azur; Observatoire de la Côte d’Azur; CNRS; Laboratoire Lagrange; Space Telescope Science Institute（加州大学洛杉矶分校; 隆德大学; 蔚蓝海岸大学; 蔚蓝海岸天文台; 法国国家科学研究中心; 拉格朗日实验室; 太空望远镜科学研究所）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究对比银河系核星团与核球化石碎片候选体Terzan 5、Liller 1，发现NSC与核球关联强但非二者简单类似体，提出BFF假说可作为识别NSC中早期核球形成组分的可证伪框架。
AI 中文摘要
银河系核星团（NSC）不同于传统球状星团：它拥有宽泛的金属丰度分布，且恒星形成于一段延展的时间区间，其详细丰度还与银河系内区核球存在紧密关联。我们探究是否应将NSC与已提出的“核球化石碎片”Terzan 5和Liller 1进行对比，这两个复杂恒星系统被解释为早期核球形成过程中涉及的大质量结构的残存遗迹。我们将该对比与Blanco DECam核球巡天测得的场核球金属丰度分布，以及NSC中的高分辨率红外丰度测量结果相结合。宽泛的金属丰度分布本身不具备诊断性，因为核球场的金属丰度分布本就宽泛且结构复杂。更具区分度的测试包括：化学上狭窄且年龄一致的子星族的存在、[α/Fe]与[Fe/H]的关系、轻元素丰度模式、空间 segregation，以及不同星族间的化学动力学差异。现有NSC数据确立了其与核球的强化学关联，但不支持其为Terzan 5或Liller 1的简单一一对应类似体。尤其值得注意的是，NSC中富金属的α增强恒星，与研究最充分的化石碎片候选体中近太阳[α/Fe]的富金属星群形成重要对比。我们认为，核球化石碎片（BFF）假说作为一个可证伪的框架最为有用，该框架用于识别通过原位恒星形成、迁移及星团吸积组装而成的复合NSC中的早期核球形成组分。
英文摘要
The Milky Way nuclear star cluster (NSC) is unlike a conventional globular cluster: it contains a broad metallicity distribution and stellar populations formed over an extended interval, while its detailed abundances show a close connection to the inner Galactic bulge. We ask whether the NSC should instead be compared with the proposed "bulge fossil fragments" Terzan 5 and Liller 1, complex stellar systems interpreted as surviving remnants of massive structures involved in early bulge assembly. We place this comparison against the field-bulge metallicity distribution measured by the Blanco DECam Bulge Survey and against high-resolution infrared abundance measurements in the NSC. A broad metallicity distribution by itself is not diagnostic, because the bulge field is intrinsically broad and strongly structured. More discriminating tests are the presence of chemically narrow and age-coherent subpopulations, the relation between [alpha/Fe] and [Fe/H], light-element abundance patterns, spatial segregation, and chemo-dynamical differences among populations. Existing NSC data establish strong chemical links with the bulge but do not support a simple one-to-one analogue of either Terzan 5 or Liller 1. In particular, metal-rich alpha-enhanced stars in the NSC provide an important contrast with the near-solar [alpha/Fe] metal-rich populations of the best-studied fossil-fragment candidates. We argue that the BFF hypothesis is most useful as a falsifiable framework for identifying an early bulge-building component within a composite NSC assembled through in-situ star formation, migration, and cluster infall.
Comments6 pages, 2 figures, contribution to IAU Symposium 405, Traversing the Galactic Center in Space and Time
