发表机构
Peking University; Kavli Institute for Astronomy and Astrophysics, Peking University; University of Chinese Academy of Science; National Astronomical Observatories, Chinese Academy of Sciences; Instituto de Física y Astronomía, Universidad de Valparaíso; Chinese Academy of Sciences South America Center for Astronomy (CASSACA), National Astronomical Observatories, CAS（北京大学; 北京大学天体物理中心; 中国科学院大学; 中国科学院国家天文台; 瓦尔帕莱索大学物理与天文研究所; 中国科学院国家天文台南美天文中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过窄带测光选出13颗极贫金属候选体并进行高分辨率光谱验证，确认4颗极贫金属星，发现钾增强r-II星，并识别出与银河系子结构相关的恒星，证明该方法高效可行。
AI 中文摘要
极贫金属（EMP；[Fe/H] < -3.0）恒星保留了银河系化学演化最早阶段的关键信息。基于一组光谱金属丰度的训练样本，我们从大规模窄带测光巡天中构建了超过120,000颗极贫金属候选体的星表。为验证该方法，我们获取了从基于SkyMapper的星表中选出的13颗候选体的高分辨率CFHT/ESPaDOnS光谱。后续观测证实，窄带测光选择能有效识别极贫金属恒星并保留相当比例的极贫金属样本：4个目标被确认为极贫金属恒星，且所有目标的[Fe/H]均低于-2.4，保持极贫金属状态。测光金属丰度系统性地低于光谱值0.44 dex，弥散相对较小，为0.19 dex，表明测光金属丰度尺度存在系统性偏移，可通过改进定标来减小。我们推导了超过20种化学元素的丰度，并识别出一颗新的钾增强r-II星J2001-1215。通过将化学丰度与轨道性质相结合，发现5颗恒星在动力学上与已知的银河系子结构一致，包括Gaia-Sausage-Enceladus、Thamnos和Sequoia。这些恒星为这些银河系子结构的极贫金属区域提供了高分辨率化学测量。这些结果凸显了窄带测光在高效选择极贫金属候选体以进行有针对性的高分辨率光谱后续观测中的作用，从而能够对早期银河系进行详细的化学和动力学研究。
英文摘要
Extremely metal-poor (EMP; [Fe/H] < -3.0) stars preserve key information about the earliest stages of Galactic chemical evolution. Based on a training set of spectroscopic metallicities, we constructed catalogs of more than 120,000 EMP candidates from large-scale narrow-band photometric surveys. To validate this approach, we obtained high-resolution CFHT/ESPaDOnS spectra for 13 candidates selected from the SkyMapper-based catalog. The follow-up observation confirms that the narrow-band photometric selection is effective in identifying very metal-poor stars and retaining a substantial EMP fraction: four targets are confirmed as EMP stars, and all targets remain very metal-poor with [Fe/H] < -2.4. The photometric metallicities are systematically lower than the spectroscopic values by 0.44 dex, with a relatively small scatter of 0.19 dex, indicating a systematic offset in the photometric metallicity scale that could be reduced through improved calibration. Abundances for more than 20 chemical species are derived, leading to the identification of a new potassium-enhanced r-II star, J2001-1215. By combining chemical abundances with orbital properties, five stars are found to be dynamically consistent with known Galactic substructures, including Gaia--Sausage--Enceladus, Thamnos, and Sequoia. These stars provide high-resolution chemical measurements for the extremely metal-poor regime of these Galactic substructures. These results underscore the role of narrow-band photometry in efficiently selecting EMP candidates for targeted high-resolution spectroscopic follow-up, thereby enabling detailed chemical and dynamical studies of the early Milky Way.
CommentsAccepted for publication in The Astrophysical Journal. 22 pages, 10 figures, and 7 tables, including machine-readable Tables 4, 5, and 7
