IACOB项目 XIX：基于经验TAMS约束重新研究大质量恒星演化——更新模型、超射校准与蓝超巨星群
The IACOB project XIX. Revisiting massive-star evolution with empirical TAMS constraints: updated models, overshoot calibration, and the population of blue supergiants
- University of Geneva（日内瓦大学）
- European Southern Observatory（欧洲南方天文台）
- Instituto de Astrofísica de Canarias（加那利群岛天体物理研究所）
- Universidad de La Laguna（拉古纳大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
该研究基于IACOB数据库观测，校准大质量单星演化模型，发现质量依赖超射效率可拟合TAMS约束，但单星模型无法解释TAMS的速度依赖性及右侧蓝超巨星群。
AI中文摘要：
大质量恒星在宇宙演化中发挥着核心作用，然而支配其演化的若干物理过程仍未得到充分约束。值得注意的是，主序带宽度对对流边界混合效率敏感；为解释大质量恒星群的部分观测特性，必须考虑双星相互作用。我们利用IACOB数据库中近期银河系大质量恒星的观测结果约束单星模型。采用最新提出的经验TAMS位置校准对流边界混合效率，并通过将各类模型预测与IACOB样本的观测恒星群进行对比，利用该校准测试单星演化。我们计算了多个GENEC网格，涵盖不同的超射校准、角动量传输（AMT）处理方式、初始质量与初始速度。最后，我们利用SYCLIST从演化轨迹生成合成恒星群，并与观测恒星群进行直接对比。慢旋转的校准模型可重现经验TAMS位置。我们发现，要拟合观测约束，需采用与质量相关的超射效率。无论AMT假设如何，单星模型都能很好地重现观测恒星群的整体旋转特性。仅考虑流体动力学不稳定性的模型可成功重现旋转特性，这与此前的GENEC网格不同，我们将此归因于星风 prescription 的选择。尽管慢旋转星的经验TAMS可被很好地重现，但我们发现模型无法解释IACOB样本中观测到的TAMS位置的速度依赖性。最后，我们发现单星模型无法解释TAMS位置右侧的蓝超巨星群。
英文摘要：
Massive stars play a fundamental role in the evolution of the Universe. Yet, several physical processes governing their evolution remain poorly constrained. Notably, the main-sequence width is sensitive to the convective boundary mixing efficiency; it becomes necessary to account for binary interactions to explain some observed properties of massive-star populations. We constrain single-star models using recent observations of massive Galactic stars from the IACOB database. We use the latest proposed empirical location of the TAMS to calibrate the convective boundary mixing efficiency, and use this calibration to test single-star evolution by comparing various model predictions to the observed populations of the IACOB sample. We compute several GENEC grids with various overshoot calibrations, angular momentum transport (AMT) treatments, initial masses and velocities. Finally, we generate synthetic populations from the tracks with SYCLIST and perform a direct comparison with the observed population. The calibrated models at slow rotation reproduce the empirical TAMS location. We find that a mass-dependent overshoot efficiency is required to fit the observational constraints. The overall rotational properties of the observed populations are well reproduced with single-star models, independently of the AMT assumptions. Models accounting only for hydrodynamical instabilities are successful at reproducing the rotational properties, unlike previous genec grids, which we attribute to the choice of winds prescription. Although the empirical TAMS of slow rotators is well reproduced, we find that models are unsuccessful at explaining the velocity dependence of the TAMS location observed in the IACOB sample. Finally, we find that single-star models fail at explaining the population of blue supergiants to the right of the TAMS location.
