arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1704.08698astro-ph.SRastro-ph.GAastro-ph.IM
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耦合流体力学与共动坐标系辐射转移:I. OB和WR星的统一方法

Coupling hydrodynamics with comoving frame radiative transfer: I. A unified approach for OB and WR stars

Andreas A. C. Sander, Wolf-Rainer Hamann, Helge Todt, Rainer Hainich, Tomer Shenar

摘要:

背景:二十多年来,恒星大气代码一直用于推导大质量恒星的恒星和风参数。虽然它们已经成为一个强大的工具,并充分再现所观察到的光谱外观,它们几乎不能用于测量参数以上。一个主要的障碍是由于使用规定的质量损失率和风速场,计算的辐射场和风层结之间的不一致。目标:我们提出了新一代流体动力学一致的非局部热平衡(非LTE)恒星大气模型,允许辐射驱动的恒星风的详细研究的概念。作为第一个演示,这种新的模型被应用到一个大质量的O型星。方法:采用正交设计法在早期工作的基础上,PoWR代码已被扩展,可选择一致地求解流体动力学方程以及统计方程和辐射转移,以获得流体动力学一致的大气层结。在这些模型中,整个速度场迭代更新连同质量损失率的调整。结果:概述了使用共运动坐标系辐射转移获得流体力学一致模型的概念。为了提供一个有用的基准,我们提出了一个演示模型,这是出于描述研究的O 4超巨星Zeta Pup。所获得的恒星和风参数在目前的文献值范围内。结论:第一次,PoWR代码已被用来获得一个流体动力学一致的大质量O星模型。这是通过对早期用于沃尔夫-拉叶星的概念进行深刻修改而实现的。速度场是由各种因素形成的,这些因素对辐射加速度有贡献,特别是在外部风中。(...)

英文摘要:

CONTEXT: For more than two decades, stellar atmosphere codes have been used to derive the stellar and wind parameters of massive stars. Although they have become a powerful tool and sufficiently reproduce the observed spectral appearance, they can hardly be used for more than measuring parameters. One major obstacle is their inconsistency between the calculated radiation field and the wind stratification due to the usage of prescribed mass-loss rates and wind-velocity fields. AIMS: We present the concepts for a new generation of hydrodynamically consistent non-local thermodynamical equilibrium (non-LTE) stellar atmosphere models that allow for detailed studies of radiation-driven stellar winds. As a first demonstration, this new kind of model is applied to a massive O star. METHODS: Based on earlier works, the PoWR code has been extended with the option to consistently solve the hydrodynamic equation together with the statistical equations and the radiative transfer in order to obtain a hydrodynamically consistent atmosphere stratification. In these models, the whole velocity field is iteratively updated together with an adjustment of the mass-loss rate. RESULTS: The concepts for obtaining hydrodynamically consistent models using a comoving-frame radiative transfer are outlined. To provide a useful benchmark, we present a demonstration model, which was motivated to describe the well-studied O4 supergiant Zeta Pup. The obtained stellar and wind parameters are within the current range of literature values. CONCLUSIONS: For the first time, the PoWR code has been used to obtain a hydrodynamically consistent model for a massive O star. This has been achieved by a profound revision of earlier concepts used for Wolf-Rayet stars. The velocity field is shaped by various elements contributing to the radiative acceleration, especially in the outer wind. (...)

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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