论文标题
恒星中R过程的化学演化（CERES）。 I.从NA到ZR的恒星参数和化学丰度
Chemical Evolution of R-process Elements in Stars (CERES). I. Stellar parameters and chemical abundances from Na to Zr
论文作者
论文摘要
目标。恒星（CERES）项目中R过程的化学演化旨在提供对金属贫困恒星样品的均匀分析（[Fe/H] <-1.5）。我们介绍了52个巨型恒星样品的恒星参数和元素的化学丰度。我们依靠一个高信号到噪声尺寸光谱的样本。我们从Gaia光度法和视差确定了恒星参数。使用光谱合成和模型大气来得出化学丰度。我们确定了26种18个元素的化学丰度：Na，Mg，Al，Si，Ca，Sc，Ti，v，Cr，Mn，Mn，Fe，Co，ni，cu，cu，cu，Zn，sr，y和Zr。对于几颗恒星，我们能够测量中性和电离物种，包括SI，SC，MN和ZR。我们在[Fe/H] <= -2.5的恒星测量值的数量大约翻了一番。样品的均匀性使得有可能突出两个富含Zn的恒星（[Zn/Fe]〜+0.7），一个R-Rich和另一个R-Poor。我们报告了[Zn/Fe]与[Ni/Fe]平面中存在两个分支的存在，并表明高[Zn/Fe]分支是高北孢核合成的结果。我们发现了两颗具有特殊光中子捕获丰度模式的恒星：CES1237+1922（也称为BS 16085-0050），在SR，Y和ZR中，与样本中的其他恒星相对于SR，Y和ZR中的其他dex不足，并且在SR，Y和ZR中也不足，并以CES2250-4057（也称为YE 2247-47-41113），这是SRE的sr，sr，sr，y和zr。和Zr.Conclusions。我们的数据集的高质量使我们无法测量无法检测到的离子。这可以为发展局部热力学平衡和流体动力学效应的偏差提供线形成计算的开发提供指导。
Aims. The Chemical Evolution of R-process Elements in Stars (CERES) project aims to provide a homogeneous analysis of a sample of metal-poor stars ([Fe/H]<-1.5). We present the stellar parameters and the chemical abundances of elements up to Zr for a sample of 52 giant stars.Methods. We relied on a sample of high signal-to-noise UVES spectra. We determined stellar parameters from Gaia photometry and parallaxes. Chemical abundances were derived using spectrum synthesis and model atmospheres.Results. We determined chemical abundances of 26 species of 18 elements: Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, and Zr. For several stars, we were able to measure both neutral and ionised species, including Si, Sc, Mn, and Zr. We have roughly doubled the number of measurements of Cu for stars at [Fe/H] <= -2.5. The homogeneity of the sample made it possible to highlight the presence of two Zn-rich stars ([Zn/Fe]~+0.7), one r-rich and the other r-poor. We report the existence of two branches in the [Zn/Fe] versus [Ni/Fe] plane and suggest that the high [Zn/Fe] branch is the result of hypernova nucleosynthesis. We discovered two stars with peculiar light neutron-capture abundance patterns: CES1237+1922 (also known as BS 16085-0050), which is ~1 dex underabundant in Sr, Y, and Zr with respect to the other stars in the sample, and CES2250-4057 (also known as HE 2247-4113), which shows a ~1 dex overabundance of Sr with respect to Y and Zr.Conclusions. The high quality of our dataset allowed us to measure hardly detectable ions. This can provide guidance in the development of line formation computations that take deviations from local thermodynamic equilibrium and hydrodynamical effects into account.
