Uncovering the cornerstones of our Universe: Application and Development of Next-Generation Stellar Atmospheres

大质量恒星及其与环境的相互作用是现代天体物理学的基石。它们的影响范围从星系化学演化的第一批恒星到超新星和引力波事件的前身。尽管它们很重要，但大质量恒星的数量影响很少受到限制，目前的描述被证明是不够的。这大大模糊了我们对上层质量区域中恒星演化的看法，并模糊了我们对依赖于恒星反馈的过程的解释，例如恒星种群合成或大质量黑洞的性质。为了约束和预测大质量恒星的性质，如它们的光谱、风和反馈，对它们不断膨胀的大气进行适当的模拟是必不可少的。这需要在非平衡环境中进行复杂的数值处理，对于非平衡环境，水动力结构传统上是通过解析描述来近似的。然而，事实证明，这种描述是不够的。特别是对于演化恒星，恒星演化预测的参数与通过模型大气获得的参数之间存在显著差异。其结果是，大质量恒星的性质和演化存在根本性的不确定性，如果将目前的描述外推到更早的宇宙时代，大质量恒星的演化可能达到数量级。对引力波事件的解释和即将到来的高红移天体物理学时代比以往任何时候都更加依赖于对大质量恒星及其反馈的强大知识。因此，我们的观测能力和我们的理论理解之间出现了危险的差距。我的艾美诺特研究小组旨在通过关注现代天体物理学领域的关键工具之一：恒星大气的应用和发展来缩小这一差距。我在过去几年的努力为新一代恒星大气铺平了道路，能够通过将辐射传输与一致的流体力学相结合来克服经典方法的局限性。有了这项技术，就有可能捕捉到热星风固有的全部物理信息，并从一组给定的恒星参数中一致地预测反馈。我的研究小组将修订我们对辐射驱动风的理解，并获得一张关于不同区域和金属含量的热星反馈的连贯图片，甚至可以追溯到第一批恒星。通过对下一代大气的分析和理论应用，我们可以追踪热星演化的所有相关阶段，并调查其对恒星种群的影响。通过耦合大气和结构模型，我们将在恒星演化中建立一个新的一致性水平。所有这些努力都将得到模型大气代码的不断扩展和改进的补充，该代码将进一步向整个天体物理界开放。

Massive stars and their interaction with the environment are keystones of modern astrophysics. Their influence ranges from the first stars over the chemical evolution of galaxies up to the progenitors of supernovae and gravitational wave events. Despite their importance, the quantitative impact of massive stars is poorly constrained and current descriptions turn out to be insufficient. This significantly blurs our perception of stellar evolution in the upper mass regime and obscures our interpretation of processes crucially dependent on stellar feedback, such as stellar population synthesis or the nature of massive black holes.To constrain and predict the properties of massive stars, such as their spectra, winds, and feedback, proper modelling of their expanding atmospheres is essential. This requires a complex numerical treatment in a non-equilibrium environment, for which the hydrodynamic structure is traditionally approximated by means of an analytical description. However, this description has proven to be insufficient. Especially for evolved stars, significant discrepancies arise between the parameters predicted by stellar evolution and those obtained via model atmospheres. The consequences are fundamental uncertainties in the properties and evolution of massive stars, which can reach orders of magnitude when extrapolating current descriptions to earlier cosmic times. The interpretation of gravitational wave events and the oncoming era of high-redshift astrophysics more than ever rely on a robust knowledge of massive stars and their feedback. Thus, a dangerous gap emerges between our observational capabilities and our theoretical understanding.My Emmy Noether research group aims at closing this gap by focussing on one of the key tools in the field of modern astrophysics: The application and development of stellar atmospheres. My efforts over the past years have paved the way for a new generation of stellar atmospheres, capable of overcoming the limitations of classical approaches by coupling the radiative transfer with consistent hydrodynamics. With this technique, it is possible to capture the full physics inherent to hot star winds and predict the feedback consistently from a given set of stellar parameters. My research group will revise our understanding of radiatively-driven winds and obtain a coherent picture of hot star feedback at different regimes and metallicities, ranging even back to the first stars. With analytical and theoretical applications of next-generation atmospheres, we can trace all relevant stages of hot star evolution and investigate the impact on stellar populations. By coupling atmosphere and structure models, we will establish a new level of consistency in stellar evolution. All of these efforts will be complemented by the constant extension and improvement of the model atmosphere code, which will further be made accessible to the whole astrophysical community.