The Elemental Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars
The Elemental Abundances in Bare Planetary Nebula Central Stars and the Shell Burning in AGB Stars
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DOI：
10.1086/500443
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发表时间：
2005-12
影响因子：
3.5
通讯作者：
K. Werner;F. Herwig
中科院分区：
文献类型：
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作者：
K. Werner;F. Herwig
我们回顾了谱型为[WC]和PG1159的极热、贫氢的后渐近巨星(AGB)的观测性质。它们的氢缺乏可能是由于(非常)晚的氦壳闪光或AGB最终的热脉冲造成的，暴露了通常隐藏在氢气包层下的恒星内部区域。因此，这些恒星的光球层元素丰度使我们能够得出关于前身AGB恒星中的核燃烧和混合过程的细节的结论。我们总结了模拟AGB演化和晚He壳层闪光发生的恒星演化模型的最新进展。我们将预测的元素丰度与用先进的非LTE模式大气进行的定量光谱分析确定的元素丰度进行比较。在定性和定量上都有很好的一致性。未来的工作将有助于更全面地了解AGB恒星的核过程。
We review the observed properties of extremely hot, hydrogen‐deficient post–asymptotic giant branch (AGB) stars of spectral type [WC] and PG1159. Their H deficiency is probably caused by a (very) late helium‐shell flash or an AGB final thermal pulse, laying bare interior stellar regions that are usually kept hidden below the hydrogen envelope. Thus, the photospheric elemental abundances of these stars allow us to draw conclusions about details of nuclear burning and mixing processes in the precursor AGB stars. We summarize the state of the art of stellar evolution models that simulate AGB evolution and the occurrence of a late He‐shell flash. We compare predicted elemental abundances to those determined by quantitative spectral analyses performed with advanced non‐LTE model atmospheres. Good qualitative and quantitative agreement is found. Future work can contribute to an even more complete picture of the nuclear processes in AGB stars.