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arXiv 1202.4787astro-ph.SR
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成团热星风中的三维辐射转移I。凝聚对共振线形成的影响

3-D radiative transfer in clumped hot star winds I. Influence of clumping on the resonance line formation

Brankica Šurlan, Wolf-Rainer Hamann, Jiří Kubát, Lidia M. Oskinova, Achim Feldmeier

备注：
Astronomy and Astrophysics, accepted for publication
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摘要：

大质量恒星的真实质量损失率对天体物理学的许多分支都很重要。对于共振线的正确建模，这是恒星质量损失的关键诊断之一，恒星风聚集是非常重要的。为了将成团纳入辐射转移计算，需要三维模型。团块的各种性质可能会对共振线的形成产生强烈的影响，因此，对经验质量损失率的确定。我们将3-D性质的恒星风聚集到辐射转移计算和研究如何不同的模型参数的影响共振线的形成。我们发展了一个完整的三维非均匀膨胀恒星风的蒙特卡罗辐射转移程序。团块的数密度遵循质量守恒。第一次，现实的3-D模型，描述了密集以及稀薄的风组件被用来模拟形成的共振线在一个成团的恒星风。同时，非单调的速度场占。三维风场密度和速度的不均匀性对共振线的形成有很大的影响。不同的参数描述的结块和速度场的结果在不同的线强度和轮廓。我们提出了一组代表性的模型，为各种模型参数，并调查如何影响的共振线。我们的3-D模型表明，线不透明度降低较大的团块分离和更浅的速度梯度内的团块。我们的新模型表明，要获得经验正确的质量损失率从紫外线共振线，风聚集和它的3-D性质必须考虑在内。

英文摘要：

The true mass-loss rates from massive stars are important for many branches of astrophysics. For the correct modeling of the resonance lines, which are among the key diagnostics of stellar mass-loss, the stellar wind clumping turned out to be very important. In order to incorporate clumping into radiative transfer calculation, 3-D models are required. Various properties of the clumps may have strong impact on the resonance line formation and, therefore, on the determination of empirical mass-loss rates. We incorporate the 3-D nature of the stellar wind clumping into radiative transfer calculations and investigate how different model parameters influence the resonance line formation. We develop a full 3-D Monte Carlo radiative transfer code for inhomogeneous expanding stellar winds. The number density of clumps follows the mass conservation. For the first time, realistic 3-D models that describe the dense as well as the tenuous wind components are used to model the formation of resonance lines in a clumped stellar wind. At the same time, non-monotonic velocity fields are accounted for. The 3-D density and velocity wind inhomogeneities show very strong impact on the resonance line formation. The different parameters describing the clumping and the velocity field results in different line strengths and profiles. We present a set of representative models for various sets of model parameters and investigate how the resonance lines are affected. Our 3-D models show that the line opacity is reduced for larger clump separation and for more shallow velocity gradients within the clumps. Our new model demonstrates that to obtain empirically correct mass-loss rates from the UV resonance lines, the wind clumping and its 3-D nature must be taken into account.

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