发表机构
The Ohio State University; The University of Hong Kong（俄亥俄州立大学; 香港大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
通过比较亚巨星观测与预测光度，推断出与金属丰度相关的氦增丰斜率，表明常用假设可能低估高金属丰度恒星的氦丰度，并影响恒星年龄与结构。
AI 中文摘要
恒星的氦丰度对其光度、内部结构和演化时标有着显著影响，然而对于大多数恒星而言，无法直接测量其氦丰度。在本工作中，我们通过比较一批亚巨星样本的观测光度与预测光度来推断恒星氦丰度，这些亚巨星具有来自APOKASC样本的星震学质量以及来自近期巡天汇编的光谱参数。恒星光度使用理论恒星演化模型网格进行预测，观测与预测之间的偏差被归因于与模型假设值不同的氦丰度差异。通过这一分析，我们看到了清晰的与金属丰度相关的氦增丰证据，$\u0394Y/\u0394Z = 1.959 \u00b1 0.061$，其中主要的误差来源是恒星基本参数的系统性差异。我们推断出的增丰斜率超过了太阳定标氦增丰关系所隐含的值，这表明通常采用的关于氦增丰的假设可能低估了高金属丰度下恒星的氦丰度。我们进一步表明，采用修正后的增丰律可以将预测的主序寿命改变多达约1 Gyr，并且在某些情况下，通过对流核发展的变化来改变恒星结构。这些结果表明，氦增丰的不确定性直接传播到恒星年龄的确定中，并强调了经验性氦约束对恒星演化模型的重要性。
英文摘要
The helium abundance of a star has a dramatic effect on luminosity, internal structure, and evolutionary timescales, yet direct helium measurements are unavailable for most stars. In this work, we infer stellar helium abundances by comparing observed and predicted luminosities for a sample of subgiants with asteroseismic masses from the APOKASC sample and spectroscopic parameters from recent survey compilations. Stellar luminosities are predicted using grids of theoretical stellar evolution models and offsets are attributed to helium differences from the assumed model value. From this analysis, we see clear evidence of helium enrichment correlated with metallicity, $ΔY/ΔZ = 1.959 \pm 0.061$, with the dominant error source being systematic differences in stellar fundamental parameters. Our inferred enrichment slope exceeds the value implied by a solar-calibrated helium enrichment relation, suggesting that commonly adopted assumptions regarding helium enrichment may underestimate stellar helium abundances at high metallicity. We further show that adopting the revised enrichment law can alter predicted main-sequence lifetimes by up to $\sim$ 1 Gyr and, in some cases, modify stellar structure through changes in convective core development. These results demonstrate that uncertainties in helium enrichment propagate directly into stellar age determinations and highlight the importance of empirical helium constraints for stellar evolution models.
Comments14 Pages, 9 Figures, Submitted to AAS Journals
