Title: New empirical mass-loss recipe for UV radiation line-driven winds of hot stars across various metallicities Show Chinese title

Title: 热星在不同金属丰度下的紫外辐射线驱动风的新经验质量损失公式

Abstract: The winds of massive stars remove a significant fraction of their mass, strongly impacting their evolution. As a star evolves, the rate at which it loses mass changes. In stellar evolution codes, different mass-loss recipes are employed for different evolutionary stages. The choice of the recipes is user-dependent and the conditions for switching between them are poorly defined. Focusing on hot stars, we aim to produce a physically motivated, empirically calibrated mass-loss recipe suitable for a wide range of metallicities. We want to provide a ready-to-use universal recipe that eliminates the need for switching between recipes for hot stars during stellar evolution calculations. We compile a sample of hot stars with reliable stellar and wind parameters in the Galaxy and the Magellanic Clouds. The sample is used to determine the dependence of the mass-loss rate on the basic stellar parameters. We find that independent of evolutionary stage and temperature, the wind mass-loss rate is a function of the electron-scattering Eddington parameter ($\Gamma_e$) and metallicity (Z), being in line with expectations of radiation-driven wind theory. Our derived scaling relation provides an adequate ($\Delta$log($\dot{M}$/(M$_\odot$/yr)) = 0.43) and broadly applicable mass-loss recipe for hot stars. The newly derived mass-loss recipe covers nearly the entire parameter space of hot stars with UV radiation-driven winds and eliminates the need for interpolation between mass-loss formulae at different evolutionary stages when applied in stellar evolution models. Examples of stellar evolution calculations using our new recipe reveal that the predictions on the ionizing fluxes and final fates of massive stars, especially at low metallicity, differ significantly from models that use the standard mass-loss rates, impacting our understanding of stellar populations at low metallicity and in the young Universe. Show Chinese abstract

Abstract: 恒星的强风会移除其大量质量，对其演化产生重大影响。 随着恒星的演化，其质量损失率会发生变化。 在恒星演化代码中，不同演化阶段采用不同的质量损失方案。 方案的选择取决于用户，并且在它们之间切换的条件定义不清。 专注于热星，我们的目标是生成一个物理驱动的、经验校准的质量损失方案，适用于广泛的金属丰度。 我们希望提供一个可以直接使用的通用方案，消除在恒星演化计算中对热星质量损失方案进行切换的需要。 我们整理了一个包含银河系和大麦哲伦星云中可靠恒星和风参数的热星样本。 该样本用于确定质量损失率与基本恒星参数之间的依赖关系。 我们发现，无论演化阶段和温度如何，风的质量损失率都是电子散射爱丁顿参数（$\Gamma_e$）和金属丰度（Z）的函数，这与辐射驱动风理论的预期一致。 我们推导出的标度关系为热星提供了足够（$\Delta$log($\dot{M}$/(M$_\odot$/yr)) = 0.43）且广泛适用的质量损失方案。 新推导出的质量损失方案涵盖了具有紫外线驱动风的热星几乎整个参数空间，并在应用于恒星演化模型时消除了在不同演化阶段之间进行插值的需要。 使用我们新方案的恒星演化计算示例表明，对大质量恒星的离解通量和最终命运的预测，特别是在低金属丰度情况下，与使用标准质量损失率的模型有显著差异，这影响了我们对低金属丰度和年轻宇宙中恒星种群的理解。