标题： APOGEE盘星的碳丰度富集作为双星物质转移的证据 显示英文标题

标题： Carbon enrichment in APOGEE disk stars as evidence of mass transfer in binaries

摘要： 第一阶段巨星中的碳丰度通常低于它们主序星的对应物。 在中等金属丰度下，单颗恒星的演化不能解释红巨星支上碳丰度增强的恒星的存在。 这种现象通常被解释为过去从一个已经演化到白矮星阶段的双星伴星的质量转移所导致的结果。 目标：我们旨在通过使用大量恒星丰度和可能的双星目录来确认[C/O]增强、s过程元素增强与双星比例之间的联系。 方法：我们利用来自 SDSS-IV/APOGEE~2 调查第17数据发布的大型数据集来识别银河盘中的碳增强恒星。 我们识别了盘星的三个不同亚群中碳富集的连续性，并探索了碳富集程度与双星频率、金属丰度和化学成分之间的联系。 结果：我们验证了二元星频率与碳和铈丰度增强之间存在清晰的相关性，这支持了碳增强恒星是由于一个演化的双星伴星质量转移的场景。 此外，我们在高$\alpha$盘恒星的碳丰度中发现了聚类现象，表明高金属丰度端的那些恒星可能较年轻，这与在富含气体的 Gaia-Enceladus/Sausage 系统合并后存在爆发星群体的理论预测一致。 显示英文摘要

摘要： Carbon abundances in first-ascent giant stars are usually lower than those of their main-sequence counterparts. At moderate metallicities, stellar evolution of single stars cannot account for the existence of red-giant branch stars with enhanced carbon abundances. The phenomenon is usually interpreted as resulting from past mass transfer from an evolved binary companion now in the white dwarf evolutionary stage. Aims: We aim to confirm the links between [C/O] enhancement, s-process element enhancement and binary fraction using large-scale catalogues of stellar abundances and probable binary stars. Methods: We use a large data set from the 17 data release of the SDSS-IV/APOGEE~2 survey to identify carbon-enhanced stars in the Galactic disk. We identify a continuum of carbon enrichment throughout three different sub-populations of disk stars and explore links between the degree of carbon enrichment and binary frequency, metallicity and chemical compositions. Results: We verify a clear correlation between binary frequency and enhancement in the abundances of both carbon and cerium, lending support to the scenario whereby carbon-enhanced stars are the result of mass transfer by an evolved binary companion. In addition, we identify clustering in the carbon abundances of high-$\alpha$ disk stars, suggesting that those on the high metallicity end are likely younger, in agreement with theoretical predictions for the presence of a starburst population following the gas-rich merger of the Gaia-Enceladus/Sausage system.