Heavy elements nucleosynthesis on accreting white dwarfs: building seeds for the p-process
Heavy elements nucleosynthesis on accreting white dwarfs: building seeds for the p-process
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DOI：
10.1093/mnras/staa2281
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发表时间：
2020-07
影响因子：
4.8
通讯作者：
U. Battino;M. Pignatari;C. Travaglio;C. Lederer-Woods;P. Denissenkov;F. Herwig;Friedrich-Karl Thielemann;T. Rauscher
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文献类型：
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作者：
U. Battino;M. Pignatari;C. Travaglio;C. Lederer-Woods;P. Denissenkov;F. Herwig;Friedrich-Karl Thielemann;T. Rauscher
太阳系中富含质子的反式铁同位素的起源仍然不确定。单简并热核超新星（SNIa）的中子俘获核合成种子组装在外层的祖先的快速吸积白色矮星阶段可能会产生这些同位素。用梅萨程序计算了5个初始质量>~ 0.85Msun的白色矮星模型吸积相的恒星结构。1，1.26，1.32和1.38Msun模型的近地表层是最具代表性的区域，其中大部分的p核是在SNIa爆炸过程中产生的，对于这些模型，我们还计算了外层的中子俘获核合成。与以前的低质量快速吸积白色矮星模型相反，我们发现H壳层灰是n-俘获核合成的主要场所。在质量最大的WD中，我们发现中子密度高达几个10^15 cm^-3。通过H壳灰的重现，这些中间中子密度可以有效地维持很长一段时间，导致高中子照射，产生高达Pb的强中子。中子密度和中子照射量都随着吸积WD质量的增加而增加。最后，使用获得的丰度作为种子计算SNIa核合成。我们得到了太阳到超太阳的p核丰度，A>96。我们的模型表明，SNIa是一个可行的p-过程生产网站。
The origin of the proton-rich trans-iron isotopes in the solar system is still uncertain. Single-degenerate thermonuclear supernovae (SNIa) with n-capture nucleosynthesis seeds assembled in the external layers of the progenitor's rapidly accreting white dwarf phase may produce these isotopes. We calculate the stellar structure of the accretion phase of five white dwarf models with initial masses >~ 0.85Msun using the stellar code MESA. The near-surface layers of the 1, 1.26, 1.32 and 1.38Msun models are most representative of the regions in which the bulk of the p nuclei are produced during SNIa explosions, and for these models we also calculate the neutron-capture nucleosynthesis in the external layers. Contrary to previous rapidly-accreting white dwarf models at lower mass, we find that the H-shell ashes are the main site of n-capture nucleosynthesis. We find high neutron densities up to several 10^15 cm^-3 in the most massive WDs. Through the recurrence of the H-shell ashes these intermediate neutron densities can be sustained effectively for a long time leading to high neutron exposures with a strong production up to Pb. Both the neutron density and the neutron exposure increase with increasing the mass of the accreting WD. Finally, the SNIa nucleosynthesis is calculated using the obtained abundances as seeds. We obtain solar to super-solar abundances for p-nuclei with A>96. Our models show that SNIa are a viable p-process production site.