s-过程化学钟的建模：来自开普勒高精度数据的见解
Modelling s-process chemical clocks: insights from high-precision Kepler data
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中文总结 AI 辅助
本研究构建s-过程化学钟的GCE模型，结合68颗开普勒红巨星的高精度星震与光谱数据，发现现有模型对年轻恒星的[Ce/Ti]低估，凸显精确星震年龄的诊断价值及当前模型的不足。
中文摘要 AI 辅助
我们提出了针对化学钟[Zr/Ti]和[Ce/Ti]的银河系化学演化（GCE）模型，这两种化学钟分别追踪第一峰和第二峰s-过程核合成，并将其与68颗开普勒红巨星的高精度样本进行比较，这些恒星具有来自单模频率的星震年龄和高分辨率光谱。利用多区域GCE框架，我们探索了金属丰度依赖的渐近巨星支（AGB）核合成产额的变化，包括对高金属丰度Ce产生的 proposed 增强。我们的基准模型在年龄和金属丰度空间中重现了[Zr/Ti]和高α序列，但在年轻年龄和中等金属丰度下系统地低估了[Ce/Ti]，这表明在银河系盘演化的最后约6 Gyr中，第二峰s-过程富集持续存在不足。增加高金属丰度AGB星的第二峰产额仅部分减少了这种差异，这表明简单的产额重新标度是不够的，可能需要对高金属丰度下的s-过程核合成进行更根本的修正，以及对恒星动力学的自洽处理。事实上，模型在金属丰度上比在年龄空间中更紧密地重现丰度趋势，额外的年龄分散部分归因于径向迁移。本通讯强调了精确星震年龄对GCE研究的诊断能力，以及当前模型在捕捉s-过程核合成与恒星动力学之间复杂相互作用方面的局限性。
英文摘要
We present Galactic chemical evolution (GCE) models for the chemical clocks [Zr/Ti] and [Ce/Ti], tracing first- and second-peak s-process nucleosynthesis, and compare them with a high-precision sample of 68 Kepler red giant stars with asteroseismic ages from individual-mode frequencies and high-resolution spectroscopy. Using a multi-zone GCE framework, we explore variations in metallicity-dependent asymptotic giant branch (AGB) nucleosynthetic yields, including proposed enhancements to high-metallicity Ce production. Our baseline model reproduces [Zr/Ti] and the high-$α$ sequence in both age and metallicity space, but systematically underestimates [Ce/Ti] at young ages and intermediate metallicities, indicating a persistent deficit in second-peak s-process enrichment over the last $\sim6$ Gyr of Galactic disc evolution. Increasing second-peak yields from high-metallicity AGB stars only partially reduces this discrepancy, suggesting that simple yield rescaling is insufficient and more fundamental revisions to s-process nucleosynthesis at high metallicity, alongside a self-consistent treatment of stellar dynamics, may be required. In fact, models reproduce abundance trends more tightly in metallicity than in age space, with additional age scatter partly attributed to radial migration. This Letter highlights the diagnostic power of precise asteroseismic ages for GCE studies and the limitations of current models in capturing the complex interplay between s-process nucleosynthesis and stellar dynamics.
