arXiv 2510.047222025-10-08astro-ph.SRastro-ph.GA

银河系球状星团47 Tuc中锶的丰度

Abundance of strontium in the Galactic globular cluster 47 Tuc

E. Kolomiecas, A. Kučinskas, J. Klevas, V. Dobrovolskas

备注：: 13 pages, 19 figures
发表信息：: A&A, 682, A126 (2024)
DOI：: 10.1051/0004-6361/202347936

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AI总结：

本研究测定47 Tuc中31颗红巨星分支星的Sr丰度，发现Sr与Na弱相关，平均[Sr/Fe]=0.18±0.08，表明污染源可能同时产生s过程元素，且可能源于低质量AGB星或大质量快速旋转星。

摘要：

目的。我们测定了位于银河系球状星团47 Tuc中的31颗红巨星分支恒星的Sr丰度，旨在识别第一星族（1P，贫Na）与第二星族（2P，富Na）恒星之间Sr丰度的潜在差异。方法。我们利用UVES光谱仪获得的档案光谱推导了Na和Sr丰度。为此，我们使用了1D ATLAS9模型大气和1D局部热动平衡光谱合成方法。特别关注评估CN谱线混合对所得Sr丰度的潜在影响。此外，我们使用CO5BOLD代码计算的3D流体动力学模型大气评估了对流对Sr谱线形成的潜在影响。结果。我们的结果提示Sr与Na丰度之间存在弱相关性。结合我们先前研究中确定的Zr与Na丰度之间的类似相关性，我们对Sr的分析表明，使2P恒星富集轻元素的污染源可能也产生了一些s过程元素。在47 Tuc的31颗红巨星分支恒星中测定的平均Sr丰度为$\langle {\rm [Sr/Fe]} \rangle = 0.18\pm0.08$（误差表示由恒星间丰度离散引起的标准偏差）。该值在类似金属丰度的银河系场星中观测到的Sr丰度变化范围内。我们样本恒星的平均[Sr/Zr]丰度比表明，这两种s过程元素可能由低质量渐近巨分支星（$M=1-4 {\rm M}_{\odot}$）或大质量（$M=10-20 {\rm M}_{\odot}$）快速旋转（$v_{\rm rot}=200-300$ km/s）恒星合成。

英文摘要：

Aims. We have determined Sr abundance in a sample of 31 red giant branch stars located in the Galactic globular cluster 47 Tuc with the aim to identify potential differences in the Sr abundance between first population (1P, Na-poor) and second population (2P, Na-rich) stars. Methods. We derived the Na and Sr abundances from the archival spectra obtained with the UVES spectrograph. To do this, we used 1D ATLAS9 model atmospheres and a 1D local thermodynamic equilibrium spectral synthesis method. Particular attention was paid to assessing the potential impact of CN line blending on the obtained Sr abundances. Furthermore, we evaluated the potential influence of convection on the Sr line formation by using 3D hydrodynamical model atmospheres computed with the CO5BOLD code. Results. Our results suggest a weak correlation between the abundances of Sr and Na. Together with a similar correlation between the abundances of Zr and Na determined in our previous study, our analysis of Sr suggests that polluters that have enriched 2P stars with light elements may have produced some s-process elements as well. The mean Sr abundance determined in 31 red giant branch stars of 47~Tuc is $\langle {\rm [Sr/Fe]} \rangle = 0.18\pm0.08$ (the error denotes the standard deviation due to the star-to-star abundance scatter). This value is within the range of the Sr abundance variation that is observed in Galactic field stars of similar metallicity. The mean [Sr/Zr] abundance ratio in our sample stars suggests that the two s-process elements could have been synthesized by either low-mass asymptotic giant branch stars ($M=1-4 {\rm M}_{\odot}$) or massive ($M=10-20 {\rm M}_{\odot}$) fast-rotating ($v_{\rm rot}=200-300$ km/s) stars.

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