论文标题
萨克斯坦矮人球形星系的早期化学演变中的同质性
Homogeneity in the early chemical evolution of the Sextans dwarf Spheroidal galaxy
论文作者
论文摘要
我们介绍了矮球星系中的两个新的极具金属贫困星（EMP）候选者的高分辨率光谱分析。这些靶标是从近红外CA II三胞胎围绕CA II三胞胎的中分辨率光谱进行预选的，并以VLT/UVE的更高分辨率进行了跟进。我们用[Fe/H] = -2.95和[Fe/H] = -3.01确认它们的低金属度，将它们置于塞克斯人已知的最贫困的恒星中。确定了18个元素的丰度，包括C，Na，α元素，Fe-peak和中子捕获元素。特别是，我们以极低的金属性介绍了经典矮人中Zn的第一个测量。与其他星系相比，塞克斯人恒星种群的丰度比以前有很大的散射比。我们借此机会重新分析了EMP的完整样本，并在固定的金属性时找到了类似乳白色的高原和正常的分散体。
We present the high-resolution spectroscopic analysis of two new extremely metal-poor stars (EMPS) candidates in the dwarf spheroidal galaxy Sextans. These targets were pre-selected from medium resolution spectra centered around the Ca II triplet in the near-infrared and followed-up at higher resolution with VLT/UVES. We confirm their low metallicities with [Fe/H]=-2.95 and [Fe/H]=-3.01, placing them among the most metal-poor stars known in Sextans. The abundances of 18 elements, including C, Na, the alpha-elements, Fe-peak, and neutron capture elements, are determined. In particular, we present the first measurements of Zn in a classical dwarf at extremely low metallicity. There has been previous hints of a large scatter in the abundance ratios of the Sextans stellar population around [Fe/H] -3 when compared to other galaxies. We took the opportunity of this work to re-analyse the full sample of EMPS and find a Milky-Way -like plateau and a normal dispersion at fixed metallicity.
