Coproduction of Light and Heavy r-process Elements via Fission Deposition
Coproduction of Light and Heavy r-process Elements via Fission Deposition
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DOI：
10.3847/1538-4357/ab91a9
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发表时间：
2019-11
期刊：
影响因子：
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通讯作者：
N. Vassh;M. Mumpower;G. McLaughlin;T. Sprouse;R. Surman
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作者：
N. Vassh;M. Mumpower;G. McLaughlin;T. Sprouse;R. Surman
我们申请的第一次裂变产率确定整个图表的核素从宏观微观理论的有限范围液滴模型的快速中子捕获（r-过程）核合成的模拟。与裂变速率和产量在相同的理论框架内用于其他相关的核数据，我们的研究结果代表了一个重要的一步，自洽应用的宏观-微观模型在r-过程计算。从这个模型的产额是广泛的极端中子过剩的核。我们发现，这些广泛分布的富中子核，特别是不对称的产额的关键物种裂变在后期的r过程中，可以显着贡献的丰度较轻的重元素，特别是轻贵金属钯和银。由于这些不对称的收益率相应地也存款到镧系元素区域，我们认为可能的证据，通过比较我们的核合成结果直接与元素比率的趋势，贫金属的恒星丰富的r-过程的材料。我们发现，对于r-过程增强的恒星钯铕和银铕显示大多是平坦的趋势暗示联产和比较镧铕的趋势，这是经常用来证明在镧系元素区域的鲁棒性参数。我们发现，这样的鲁棒性参数可以扩展到钯和更重，并表明裂变沉积是一种机制，通过这种机制可以实现这样的普遍性或鲁棒性。
We apply for the first time fission yields determined across the chart of nuclides from the macroscopic-microscopic theory of the Finite Range Liquid Drop Model to simulations of rapid neutron capture (r-process) nucleosynthesis. With the fission rates and yields derived within the same theoretical framework utilized for other relevant nuclear data, our results represent an important step toward self-consistent applications of macroscopic-microscopic models in r-process calculations. The yields from this model are wide for nuclei with extreme neutron excess. We show that these wide distributions of neutron-rich nuclei, and particularly the asymmetric yields for key species that fission at late times in the r process, can contribute significantly to the abundances of the lighter heavy elements, specifically the light precious metals palladium and silver. Since these asymmetric yields correspondingly also deposit into the lanthanide region, we consider the possible evidence for coproduction by comparing our nucleosynthesis results directly with the trends in the elemental ratios of metal-poor stars rich in r-process material. We show that for r-process enhanced stars palladium over europium and silver over europium display mostly flat trends suggestive of coproduction and compare to the lanthanum over europium trend which is often used to justify robustness arguments in the lanthanide region. We find that such robustness arguments may be extendable down to palladium and heavier and demonstrate that fission deposition is a mechanism by which such a universality or robustness can be achieved.