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arXiv · 2508.00671

Chemical abundances of seven stars in the GD-1 stream

Jing-Kun Zhao·Guang-Wei Li·Wako Aoki·Gang Zhao·Guo-Chao Yang·Jian-Rong Shi·Hai-Ning Li·Tadafumi Matsuno·Miho Ishigaki·Takuma Suda·Satoshi Honda·Yu-Qin Chen·Qian-Fan Xing·Hong-Liang Yan·Yong Yang·Xian-Hao Ye
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Abstract

We present the first detailed chemical abundances for seven GD-1 stream stars from Subaru/HDS spectroscopy. Atmospheric parameters were derived via color calibrations ($T\rm_{eff}$) and iterative spectroscopic analysis. LTE abundances for 14 elements ($\alpha$, odd-Z, iron-peak, n-capture) were measured. Six stars trace the main orbit, one resides in a `blob'. All exhibit tightly clustered metallicities ([Fe/H] = -2.38, {\bf intrinsic dispersion smaller than 0.05 dex, average uncertainty is about 0.13 dex}). While one star shows binary mass transfer signatures, the other six display consistent abundance patterns (dispersions $<$ uncertainties). Their iron-peak elements (Sc, Cr, Mn, Ni) match Milky Way halo stars. In contrast, Y and Sr are systematically lower than halo stars of similar [Fe/H]. Significantly, six stars show consistently enhanced [Eu/Fe] $\sim$ 0.60 ($\sigma$ = 0.08). A tight Ba-Eu correlation (r = 0.83, p=0.04) exists, with [Ba/Fe] = -0.03 $\pm$ 0.05, indicating a common r-process origin. This extreme chemical homogeneity strongly supports an origin from a single disrupted globular cluster. The lack of light-element anti-correlations may stem from our sample size or the progenitor's low mass.

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Jing-Kun Zhao, Guang-Wei Li, Wako Aoki, Gang Zhao, Guo-Chao Yang, Jian-Rong Shi, Hai-Ning Li, Tadafumi Matsuno, Miho Ishigaki, Takuma Suda, Satoshi Honda, Yu-Qin Chen, Qian-Fan Xing, Hong-Liang Yan, Yong Yang, Xian-Hao Ye. 2025-08-01. Chemical abundances of seven stars in the GD-1 stream. https://arxiv.org/abs/2508.00671

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