Element abundance patterns in stars indicate fission of nuclei heavier than uranium

I. U. Roederer, N. Vassh, E. Holmbeck, M. Mumpower, R. Surman, J. J. Cowan, T. C. Beers, R. Ezzeddine, A. Frebel, V. M. Placco, C. M. Sakari

Published Science 382 6675 1177 (2023)

The heaviest elements observed in the universe are produced by the rapid neutron-capture process (r-process). Its termination among transuranic nuclei is poorly understood because these elements are inaccessible to experiments, forcing nuclear models to extrapolate from limited constraints. We show that the elements Ru, Rh, Pd, and Ag (atomic numbers 44<=Z<=47, mass numbers 99<=A<=110) exhibit a correlation with abundances of heavier elements (63<=Z<=78, A>150) that is not shared by their immediate neighbors (34<=Z<=42 and 48<=Z<=62) for stars that are enhanced in r-process elements. Coproduction via fission fragments of transuranic nuclei provides the most compelling explanation for this behavior. We conclude that this signature provides the first evidence that neutron-rich fissioning nuclei with mass numbers >260 are produced in r-process events, such as neutron-star mergers.


r-process nuclear fission metal poor stars

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