Radiation-driven winds of hot luminous stars - XVII. Parameters of selected central stars of PN from consistent optical and UV spectral analysis and the universality of the mass-luminosity relation
Radiation-driven winds of hot luminous stars - XVII. Parameters of selected central stars of PN from consistent optical and UV spectral analysis and the universality of the mass-luminosity relation
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热发光恒星的辐射驱动风 - XVII。
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
T. Hoffmann
中科院分区：
文献类型：
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作者：
C. B. Kaschinski;A. Pauldrach;T. Hoffmann
上下文行星状星云中心恒星的质量-光度关系可能并不普遍适用。虽然大气参数Teff，logg和He丰度在过去已经确定使用拟合光球H和He吸收线从平面平行模型大气，质量和光度不能独立地导出这种方式，而是从理论演化模型。改进流体动力学自洽建模的恒星大气流出，现在允许使用适合的风敏感功能的紫外光谱，以一贯地确定恒星的半径，质量和光度，而无需假设的质量-光度关系。在本系列的早期论文中，最近对CSPN样本的应用提出了关于行星状星云中心恒星质量-光度关系的有效性的问题。目标。早期的UV分析的结果进行重新评估的同时比较所观察到的光学和UV光谱与相应的合成光谱。合成的光学和紫外光谱计算同时从相同的大气模型，使用相同的模型大气代码。两颗中心恒星NGC 6826和NGC 2392的合成光谱是使用两个不同的已发表分析的参数集计算的，以检查它们与观测的兼容性。方法.使用不同的公布的恒星参数集，一方面来自一致的UV分析，另一方面从适合光学H和He线，我们计算相应的光学和UV光谱与我们的模型大气代码。我们已经改进了这个模型的大气代码通过实施斯塔克加宽的氢和氦线，从而使我们能够获得一致的光学H和He线的轮廓，同时与我们的国家的最先进的紫外光谱建模。结果与一致的参数集从UV分析计算的光学线轮廓产生线轮廓与观测结果具有良好的一致性（发射线的小差异对应于质量损失率的一半左右）。光谱计算与恒星参数集从文献中的光学分析和相应的一致的风参数，然而，观察到的光谱，在光学以及在紫外线显示出很大的差异。我们的结论是，发表的光学分析得到很好的拟合观测光谱，只是因为在这些分析中假设的风参数是不一致的恒星参数。通过加强恒星和风参数之间的一致性，得到了与两个分析对象的核质光关系不一致的恒星参数。从一个完全不同的方法中也可以明显看出这种分歧：对动态风参数的研究。
Context. The commonly accepted mass-luminosity relation of central stars of planetary nebulae (CSPNs) might not be universally valid. While the atmospheric parameters Teff ,l ogg, and the He abundances have in the past been determined using fits to photospheric H and He absorption lines from plane-parallel model atmospheres, the masses and luminosities could not be derived independently this way, and were instead taken from theoretical evolutionary models. Improvements in hydrodynamically selfconsistent modelling of the stellar atmospheric outflows now allow using fits to the wind-sensitive features in the UV spectra to consistently determine the stellar radii, masses, and luminosities without assuming a mass-luminosity relation. Recent application to a sample of CSPNs in an earlier paper of this series raised questions regarding the validity of the mass-luminosity relation of central stars of planetary nebulae. Aims. The results of the earlier UV analysis are reassessed by means of a simultaneous comparison of both the observed optical and UV spectra with corresponding synthetic spectra. The synthetic optical and UV spectra are computed simultaneously from the same atmospheric models, using the same model atmosphere code. Synthetic spectra for the two central stars NGC 6826 and NGC 2392 are computed using parameter sets from two different published analyses to check their compatibility to the observations. Methods. Using the different published stellar parameter sets, derived on the one hand by a consistent UV analysis, and on the other hand from fits to optical H and He lines, we calculate corresponding optical and UV spectra with our model atmosphere code. We have improved this model atmosphere code by implementing Stark broadening for hydrogen and helium lines, thus allowing us to obtain consistent optical H and He line profiles simultaneously with our state-of-the-art modelling of the UV-spectrum. Results. Optical line profiles computed with the consistent parameter sets from the UV analysis yield line profiles with good agreement to the observations (with small discrepancies in the emission lines corresponding to about a factor of one half in the mass loss rate). Spectra computed with the stellar parameter sets from the optical analysis in the literature and corresponding consistent wind parameters, however, show large discrepancies to the observed spectra, in the optical as well as in the UV. We conclude that the published optical analyses give good fits to the observed spectrum only because the wind parameters assumed in these analyses are inconsistent to their stellar parameters. By enforcing consistency between stellar and wind parameters, stellar parameters are obtained which disagree with the core-mass-luminosity relation for the two objects analyzed. This disagreement is also evident from a completely different approach: an investigation of the dynamical wind parameters.
影响因子：
6.5
作者：
A. Pauldrach;D. Vanbeveren;D. Vanbeveren;T. Hoffmann
通讯作者：
A. Pauldrach;D. Vanbeveren;D. Vanbeveren;T. Hoffmann