The effect of diffusion on prenova evolution: CNO-enriched envelopes
The effect of diffusion on prenova evolution: CNO-enriched envelopes
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DOI：
10.1086/162107
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发表时间：
1984-06
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影响因子：
--
通讯作者：
D. Prialnik;A. Kovetz
中科院分区：
文献类型：
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作者：
D. Prialnik;A. Kovetz
我们研究了一颗包层为10~(-5)M/次太阳/富氢(Z=0.03)的I.25M/subSUN/C-O白矮星的核-包层边界的扩散效应。扩散方程，包括浓度、压力和热项，连同三种气体的演化方程一起被求解：H，He和第三组分，代表所有存在的CNO元素。几个具有不同初始亮度的模型被进化，直到发展出热核失控。在核包层边界，重元素向外扩散，导致包层底部无明显的CNO富集区。同样，但更重要的是，少量的氢向内扩散，导致氢在非常高的Z区着火。因此，在初始核-包层界面下方的某个深度处发生了热核失控。当燃烧峰上方的整个区域变得对流不稳定时，大量富含C-O的物质被混合到包层中，使Z值增加到0.27。在初始光度较低的模型中，漫射效应较强。白矮星表面附近的重元素沉积对于新星的典型时间尺度来说并不重要。更多？我们讨论了这些结果与快速新星模型的相关性。
We have investigated the effect of diffusion at the core-envelope boundary of a I.25 M/sub sun/ C-O white dwarf with a 10-5 M/sub sun/ H-rich envelope (with Z = 0.03), a typical nova progenitor. The diffusion equations, which include concentration, pressure, and thermal terms, were solved along with the evolution equations for a mixture of three gases: H, He, and a third component, representative of all CNO elements present. Several models with different initial luminosities were evolved until a thermonuclear runaway developed. At the core-envelope boundary, heavy elements diffused outward, resulting in an insignificant CNO enrichment at the base of the envelope. Similarly, but more significantly, small amounts of H diffused inward, leading to H ignition in a very high Z zone. Thus, a thermonuclear runaway occurred at some depth below the initial core-envelope interface. As in time the entire region above the burning peak became convectively unstable, large amounts of C-O-rich matter were mixed into the envelope, increasing the values of Z up to 0.27. The effect of diffusion was stronger in models with lower initial luminosity. Sedimentation of heavy elements near the surface of the white dwarf was found to be unimportant for time scales typical of novae.more » We discuss the relevance of these results to models of fast novae.« less