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arXiv 2108.08969astro-ph.SR
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Keck/HIRES光谱中三颗新Ba星的化学丰度

Chemical abundances of three new Ba stars from the Keck/HIRES spectra

Shuai Liu, Liang Wang, Jian-Rong Shi, Zhen-Yu Wu, Hong-Liang Yan, Qi Gao, Chun-Qian Li

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Accepted for publication in RAA, 21 pages, 10 figures
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摘要：

基于Keck/HIRES的高分辨率、高信噪比（S/N）谱，我们测定了18个Ba候选元素中20个元素的丰度。这些恒星的参数空间的范围是4880 $\leq$ $\rm{T_{eff}}$ $\leq$ 6050 K，2.56 $\leq$ log $g$ $\leq$ 4.53 dex和-0.27 $\leq$ [Fe/H] $\leq$ 0.09 dex。其中4颗是Ba星，[s/Fe] $>$ = 0.25 dex（s：Sr，Y，Zr，Ba，La，Ce和Nd），另外3颗是新发现的，包括2颗Ba巨星（HD 16178和HD 22233）和1颗Ba亚巨星（HD 2946）。结果表明，我们的程序星的$α$、奇峰和铁峰元素（O、Na、Mg、Al、Si、Ca、Sc、Ti、Mn、Ni和Cu）的丰度与薄盘相似，而Ba星的[hs/ls]（hs：Ba、La、Ce和Nd，ls：Sr、Y和Zr）比值的分布与已知Ba天体相似。四颗Ba星中没有一颗显示出明显的碳增强，包括已知的CH亚巨星HD 4395。根据径向速度数据，发现其中三颗Ba星存在恒星或亚恒星伴星的明显证据。

英文摘要：

Based on high resolution, high signal-to-noise (S/N) ratio spectra from Keck/HIRES, we have determined abundances of 20 elements for 18 Ba candidates. The parameter space of these stars are in the range of 4880 $\leq$ $\rm{T_{eff}}$ $\leq$ 6050 K, 2.56 $\leq$ log $g$ $\leq$ 4.53 dex and -0.27 $\leq$ [Fe/H] $\leq$ 0.09 dex. It is found that four of them can be identified as Ba stars with [s/Fe] $>$ 0.25 dex (s: Sr, Y, Zr, Ba, La, Ce and Nd), and three of them are newly discovered, which includes two Ba giants (HD 16178 and HD 22233) and one Ba subgiant (HD 2946). Our results show that the abundances of $α$, odd and iron-peak elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, Mn, Ni and Cu) for our program stars are similar to those of the thin disk, while the distribution of [hs/ls] (hs: Ba, La, Ce and Nd, ls: Sr, Y and Zr) ratios of our Ba stars is similar to those of the known Ba objects. None of the four Ba stars show clear enhancement in carbon including the known CH subgiant HD 4395. It is found that three of the Ba stars present clear evidences of hosting stellar or sub-stellar companions from the radial velocity data.

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