Context. Radiation-driven mass loss plays a key role in the life cycles of massive stars. However, basic predictions of such mass loss still suffer from significant quantitative uncertainties. Aims. We develop new radiation-driven, steady-state wind models for massive stars with hot surfaces, suitable for quantitative predictions of global parameters like mass-loss and wind-momentum rates. Methods. The simulations presented here are based on a self-consistent, iterative grid solution to the spherically symmetric, steady-state equation of motion, using full non-local thermodynamic equilibrium radiative transfer solutions in the co-moving frame to derive the radiative acceleration. We do not rely on any distribution functions or parametrization for computation of the line force responsible for the wind driving. The models start deep in the subsonic and optically thick atmosphere and extend up to a large radius at which the terminal wind speed has been reached. Results. In this first paper, we present models representing two prototypical O-stars in the Galaxy, one with a higher stellar mass M _(*)∕ M _(⊙)= 59 and luminosity log_(10) L _(*)∕ L _(⊙)= 5.87 (spectroscopically an early O supergiant) and one with a lower M _(*)∕ M _(⊙)= 27 and log_(10) L _(*)∕ L _(⊙)= 5.1 (a late O dwarf). For these simulations, basic predictions for global mass-loss rates, velocity laws, and wind momentum are given, and the influence from additional parameters like wind clumping and microturbulent speeds is discussed. A key result is that although our mass-loss rates agree rather well with alternative models using co-moving frame radiative transfer, they are significantly lower than those predicted by the mass-loss recipes normally included in models of massive-star evolution. Conclusions. Our results support previous suggestions that Galactic O-star mass-loss rates may be overestimated in present-day stellar evolution models, and that new rates might therefore be needed. Indeed, future papers in this series will incorporate our new models into such simulations of stellar evolution, extending the very first simulations presented here toward larger grids covering a range of metallicities, B supergiants across the bistability jump, and possibly also Wolf-Rayet stars.
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机译：上下文。辐射驱动的质量损失在大质量恒星的生命周期中起着关键作用。但是，这种质量损失的基本预测仍然存在明显的定量不确定性。目的我们为具有热表面的大质量恒星开发了新的辐射驱动的稳态风模型，适用于定量估计质量损失和风动量率等全球参数。方法。此处提供的模拟基于球对称，稳态运动方程的自洽迭代网格解，在同向运动框架中使用完整的非局部热力学平衡辐射传递解来得出辐射加速度。我们不依赖任何分布函数或参数化来计算负责风力驱动的线力。这些模型从亚音速和光学较厚的大气层深处开始，一直延伸到达到终端风速的大半径。结果。在第一篇论文中，我们提出了代表银河系中两个原型O恒星的模型，其中一个恒星质量M _（*）∕ M _（⊙）= 59且光度log_（10）L _（*）∕ L _（⊙）= 5.87（光谱上是早期的O超级巨人），并且M _（*）∕ M _（⊙）= 27并且log_（10）L _（*）∕ L _（⊙）= 5.1（已故的O矮人）。对于这些模拟，给出了总体质量损失率，速度定律和风动量的基本预测，并讨论了诸如风团和微湍流速度等其他参数的影响。一个关键的结果是，尽管我们的质量损失率与使用共同移动框架辐射传输的替代模型相当吻合，但它们远低于通常由质量恒星演化模型中包括的质量损失公式所预测的质量损失率。结论。我们的结果支持了先前的建议，即在当今的恒星演化模型中可能会高估银河系O星质量损失率，因此可能需要新的率。的确，本系列的未来论文将把我们的新模型结合到这样的恒星演化模拟中，从而将此处介绍的第一个模拟扩展到覆盖一定金属范围的更大网格，双稳性跃迁上的B超巨星以及可能还有Wolf-Rayet星。
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