Abstract
Rapid neutron capture nucleosynthesis involves thousands of nuclear species far from stability, whose nuclear properties need to be understood in order to accurately predict nucleosynthetic outcomes. Recently sensitivity studies have provided a deeper understanding of how the r process proceeds and have identified pieces of nuclear data of interest for further experimental or theoretical study. A key result of these studies has been to point out the importance of individual neutron capture rates in setting the final r-process abundance pattern for a ‘main’ (A ∼ 130 peak and above) r process. Here we examine neutron capture in the context of a ‘weak’ r process that forms primarily the A ∼ 80 r-process abundance peak. We identify the astrophysical conditions required to produce this peak region through weak r-processing and point out the neutron capture rates that most strongly influence the final abundance pattern.
Highlights
In the 1950s it was recognized that the solar system abundances of nuclei heavier than iron could be divided roughly in half based on the nucleosynthesis processes that create them.[1,2] Slow neutron capture process, or s-process, nuclei lie along the middle of the valley of stability, and rapid neutron capture process, or r-process, nuclei are found on the neutron-rich side of stability
The neutron capture rate sensitivity study procedure was repeated for the approximately ninety astrophysical trajectories chosen for this investigation
We have examined the role of neutron capture of A = 80 nuclei in the context of a weak r process from winds that could occur in supernova or collapsar accretion disks
Summary
In the 1950s it was recognized that the solar system abundances of nuclei heavier than iron could be divided roughly in half based on the nucleosynthesis processes that create them.[1,2] Slow neutron capture process, or s-process, nuclei lie along the middle of the valley of stability, and rapid neutron capture process, or r-process, nuclei are found on the neutron-rich side of stability. Pattern for elements from barium to lead (‘main’ r process) but large scatter below barium.[9] It may be that these light elements owe their origins to a range of nucleosynthesis processes, some of which may even be proton-rich; the question is difficult to answer without isotopic information for the halo star abundances (see, e.g., Ref. 10 and references therein). Given this uncertainty, the production mechanism for these elements has often been dubbed the light element primary process, or LEPP.
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