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arXiv 1012.2213astro-ph.SRastro-ph.HEnucl-exphysics.space-ph
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爆炸核合成中p核的起源

Origin of the p-Nuclei in Explosive Nucleosynthesis

T. Rauscher

摘要:

许多天然存在的富含质子的核素(p核)不能在s和r过程中产生。已经发现,大质量恒星可以通过光致蜕变产生p核,这是由已经存在的中重核和重核所引起的。这种所谓的伽马过程需要足够高的温度,并发生在预爆炸或爆炸O/Ne燃烧中,取决于恒星的质量。虽然伽马过程已经成功地产生了大范围的p核,但两个质量区域仍然存在问题,A<110和150<A<165,其中许多p核严重不足。问题的根源尚待查明。在反应网络中包含大量的不稳定核,这些核只有理论上预测的反应速率,因此核输入可能包含不确定性。在γ过程温度下,已发现稳定核的带电粒子光学势的亏损。另一方面,伽马过程的条件(温度曲线,熵的O壳,种子成分)也敏感地依赖于恒星的结构和演化的细节,以及对初始金属丰度。然而,特别是缺乏的低质量p-核可能需要额外的生产过程或地点,例如在Ia型超新星(subbrasrasekhar)中的生产。此外,在RP和NU-P-过程中的合成(IM)的可能性进行了讨论。如果是这样的话,p核的产生将是几个不同过程的叠加,而不一定是在同一地点。

英文摘要:

A number of naturally occurring, proton-rich nuclides (the p-nuclei) cannot be made in the s- and r-process. It has been found that massive stars can produce p-nuclei through photodisintegration of pre-existing intermediate and heavy nuclei. This so-called gamma-process requires sufficiently high temperatures and occurs in pre-explosive or explosive O/Ne burning, depending on the mass of the star. Although the gamma-process has been successful in producing a large range of p-nuclei, two mass regions remain problematic, A<110 and 150<A<165, where a number of p-nuclei are severely underproduced. The origin of the problems is yet to be identified. A large number of unstable nuclei with only theoretically predicted reaction rates are included in the reaction network and thus the nuclear input may involve uncertainties. Deficiencies in charged-particle optical potentials at gamma-process temperatures have been found for nuclei at stability. On the other hand, the gamma-process conditions (temperature profiles, entropy of the O shell, seed composition) also sensitively depend on details of the stellar structure and evolution, as well as on the initial metallicity. Nevertheless, especially the deficient low-mass p-nuclei may call for an additional production process or site, such as production in (subChandrasekhar) type Ia supernovae. Also the (im)possibility of a synthesis in the rp- and nu-p-processes is discussed. Were this the case, the production of p-nuclei would be realized as a superposition of several different processes, not necessarily in the same site.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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