标题： 从Carina矮椭球星系中碳增强的贫金属恒星中得到的多重核合成过程的证据 显示英文标题

标题： Evidence for multiple nucleosynthetic processes from carbon enhanced metal-poor stars in the Carina dwarf spheroidal galaxy

摘要： 上下文：碳增强的贫金属（CEMP）恒星（$\mathrm{[C/Fe]} > 0.7$）在银河系晕中低金属度区域大量存在，是早期银河系化学演化的重要示踪物。然而，在经典矮椭球星系（dSph）中很少发现这样的恒星，且详细的丰度数据，包括中子俘获元素的丰度，仅对12颗恒星进行了报道。目标：我们旨在推导在Carina dSph中识别出的六颗CEMP恒星的详细丰度，并将这些丰度与其他dSph星系和银河系晕中的CEMP恒星进行比较。这是迄今为止在dSph星系中分析的最大CEMP恒星样本。方法：通过使用拉斯坎帕纳斯天文台的MIKE光谱仪获得的六颗恒星的高分辨率光谱，采用等效宽度和光谱合成方法推导一维LTE元素丰度。结果：在六颗恒星中，从碳到锇的最多27种元素的丰度或上限被推导出来。分析显示其中一颗恒星为CEMP-no恒星，其中子俘获元素丰度非常低。相反，其他五颗恒星除了碳增强外，还显示出中子俘获元素的增强，将其归类为CEMP-$s$和 -$r/s$恒星。六颗恒星的$\alpha$和铁峰元素丰度与其他Carina星系中的恒星相似，除了CEMP-no恒星，它表现出钠、镁和硅的增强。我们探讨了dSph星系中CEMP恒星的绝对碳丰度（$A(\rm C)$），发现其行为与银河系晕中的CEMP恒星类似，但强调CEMP-$r/s$恒星主要具有非常高的$A(\rm C)$值。 我们还将样本中CEMP-$r/s$星星的中子俘获元素丰度与最近的$i$-过程产率进行了比较，这些产率与推导出的丰度相匹配。 显示英文摘要

摘要： Context: Carbon Enhanced Metal-Poor (CEMP) stars ($\mathrm{[C/Fe]} > 0.7$) are known to exist in large numbers at low metallicity in the Milky Way halo and are important tracers of early Galactic chemical evolution. However, very few such stars have been identified in the classical dwarf spheroidal (dSph) galaxies, and detailed abundances, including neutron-capture element abundances, have only been reported for 12 stars. Aims: We aim to derive detailed abundances of six CEMP stars identified in the Carina dSph and compare the abundances to CEMP stars in other dSph galaxies and the Milky Way halo. This is the largest sample of CEMP stars in a dSph galaxy analysed to date. Methods: 1D LTE elemental abundances are derived via equivalent width and spectral synthesis using high-resolution spectra of the six stars obtained with the MIKE spectrograph at Las Campanas Observatory. Results: Abundances or upper limits are derived for up to 27 elements from C to Os in the six stars. The analysis reveals one of the stars to be a CEMP-no star with very low neutron-capture element abundances. In contrast, the other five stars all show enhancements in neutron-capture elements in addition to their carbon enhancement, classifying them as CEMP-$s$ and -$r/s$ stars. The six stars have similar $\alpha$ and iron-peak element abundances as other stars in Carina, except for the CEMP-no star, which shows enhancement in Na, Mg, and Si. We explore the absolute carbon abundances ($A(\rm C)$) of CEMP stars in dSph galaxies and find similar behaviour as is seen for Milky Way halo CEMP stars, but highlight that CEMP-$r/s$ stars primarily have very high $A(\rm C)$ values. We also compare the neutron-capture element abundances of the CEMP-$r/s$ stars in our sample to recent $i$-process yields, which provide a good match to the derived abundances.