arXiv:2312.06844·v1·Solar and Stellar Astrophysics
Element abundance patterns in stars indicate fission of nuclei heavier than uranium
Ian U. Roederer · Nicole Vassh · Erika M. Holmbeck · Matthew R. Mumpower · Rebecca Surman · John J. Cowan · Timothy C. Beers · Rana Ezzeddine · Anna Frebel · Terese T. Hansen · Vinicius M. Placco · Charli M. Sakari
Abstract
The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and inaccessible to experiments, so must be extrapolated using nucleosynthesis models. We examine element abundances in a sample of stars that are enhanced in r-process elements. The abundances of elements Ru, Rh, Pd, and Ag (atomic numbers Z = 44 to 47, mass numbers A = 99 to 110) correlate with those of heavier elements (63 <= Z <= 78, A > 150). There is no correlation for neighboring elements (34 <= Z <= 42 and 48 <= Z <= 62). We interpret this as evidence that fission fragments of transuranic nuclei contribute to the abundances. Our results indicate that neutron-rich nuclei with mass numbers >260 are produced in r-process events.
Comments: Authors' version of manuscript published in Science on December 07, 2023