Title: Gaia Barium Dwarfs and Their Ostensibly Ordinary Counterparts Show Chinese title

Title: 盖亚钡矮星及其看似普通的对应星体

Abstract: The recently identified Gaia population of main-sequence--white dwarf (MS+WD) binaries at separations of ${\sim}\,1~{\rm AU}$, often with moderate eccentricities, is not readily reproduced by binary population synthesis models. Barium stars represent a closely related population whose enrichment in $s$-process elements both confirms the presence of a WD companion and attests to past binary interaction. It also indicates that mass transfer occurred at least during the late- and post-AGB phases of the WD progenitor, when $s$-process elements are dredged up. In this work, we further explore the connection between the astrometrically identified Gaia MS+WD binaries and the classical barium star population. To achieve this, we used high-resolution FEROS spectroscopy to measure abundances for 30 Gaia DR3 non-single-star binaries, identifying 10 as Ba-enriched. Together with our recent analysis of archival GALAH data, this yields a sample of 38 barium dwarfs with dynamically measured WD masses, compared to only 6 previously known systems with known WD masses at these separations. We find that, in cases where metallicity is sufficiently low to facilitate efficient $s$-process production, barium and yttrium enrichment is often detected. This enrichment is also identified in eccentric systems, suggesting that post-AGB mass transfer mechanisms are capable of pumping eccentricity into the orbit or occur without erasing it. Our results indicate that the Gaia MS+WD binaries trace the population from which barium stars emerge. Treating the large Gaia-discovered population as an extension of known $s$-process enriched dwarfs opens an avenue to empirically constrain their formation and evolution. Show Chinese abstract

Abstract: 最近发现的在分离度为${\sim}\,1~{\rm AU}$的主序星-白矮星（MS+WD）双星群体，通常具有中等偏心率，但难以被双星种群合成模型再现。 钡星代表一个密切相关的群体，其在$s$-过程元素方面的富集既确认了白矮星伴星的存在，也证明了过去双星之间的相互作用。 这也表明，在白矮星前体的晚期和后渐近巨星分支阶段，发生了质量转移，此时$s$-过程元素被翻到表面。 在本研究中，我们进一步探讨了天体测量识别的盖亚MS+WD双星与经典钡星群体之间的联系。 为了实现这一目标，我们使用高分辨率 FEROS 光谱学测量了30个盖亚DR3非单星双星的丰度，其中10个被识别为钡富集的。 结合我们对档案GALAH数据的近期分析，这产生了一个包含38个钡矮星的样本，这些样本具有动态测量的白矮星质量，相比之下，此前仅知道6个在这些分离度下具有已知白矮星质量的系统。 我们发现，在金属量足够低以促进有效$s$-过程产物生成的情况下，通常可以检测到钡和钇的富集。 这种富集也出现在偏心系统中，表明后渐近巨星分支的质量转移机制能够将偏心率注入轨道或在不消除偏心率的情况下发生。 我们的结果表明，盖亚MS+WD双星描绘了钡星出现的群体。 将大量盖亚发现的群体视为已知$s$-过程富集矮星的延伸，为经验性地约束它们的形成和演化开辟了一条途径。