Sodium Abundances in Very Metal-poor Stars

被引：0

作者：

Yu-Fu Shen ^{[1
,2
]}

S.A.Alexeeva ^{[1
]}

Gang Zhao ^{[1
,2
]}

Shuai Liu ^{[1
,2
]}

Zeming Zhou ^{[1
,2
]}

Hongliang Yan ^{[1
,2
]}

Haining Li ^{[1
]}

Tianyi Chen ^{[1
,2
]}

Xiaodong Xu ^{[1
,2
]}

Huiling Chen ^{[3
,4
]}

Huawei Zhang ^{[3
,4
]}

Jianrong Shi ^{[1
]}

机构：

[1] CAS Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences

[2] School of Astronomy and Space Science, University of Chinese Academy of Sciences

[3] Department of Astronomy, School of Physics, Peking University

[4] Kavli Institute for Astronomy and Astrophysics, Peking University

来源：

Research in Astronomy and Astrophysics | 2023年 / 23卷 / 07期

基金：

国家重点研发计划; 中国国家自然科学基金;

关键词：

D O I：

暂无

中图分类号：

P148 [天体化学];

学科分类号：

070401 ;

摘要：

Chemical composition of very metal-poor(VMP) stars can provide observational constraints on current models of nucleosynthesis and the chemical evolution of the Galaxy.It has been found that the scatter of [Na/Fe] versus [Fe/H] in VMP stars is very large in contrast with most other elements.Moreover,a negative slope in [Na/Fe] versus[Fe/H] was found for giants,which is very unlikely according to the theory of nucleosynthesis.For the sample of93 VMP stars in the metallicity range-4.25 <[Fe/H] <-1.64 we obtained NLTE sodium abundances using the line profile fitting method by employing accurate atmospheric parameters determined when taking into account NLTE line formation for both FeⅠ and Fe Ⅱ.Originally selected from the LAMOST low-resolution spectral database,the spectra of stars were obtained with the High Dispersion Spectrograph of the Subaru Telescope.For 57turn-off stars in metallicity domain-3.04 <[Fe/H] <-1.64,we obtained mean [Na/Fe]=-0.29±0.14 and positive slope 0.09±0.06.For 21 giants distributed over metallicity-3.59 <[Fe/H] <-2.19,we found mean[Na/Fe]=-0.35±0.1 and positive slope 0.07±0.07.Our [Na/Fe] trend is lower by ～0.2 dex,compared to the modern GCE model.We believe the GCE model should be adjusted,by considering the associated scatter.Twelve stars in our sample are found to be outliers,with too low or too high Na abundances.

引用

页码：231 / 248

页数：18

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