129I and 247Cm in meteorites constrain the last astrophysical source of solar r-process elements

1,2,3Benoit Côté et al. (>10)
Science 371, 945-948 Link to Article [DOI: 10.1126/science.aba1111]
1Research Centre for Astronomy and Earth Sciences, Eötvös Loránd Research Network, Konkoly Observatory, 1121 Budapest, Hungary.
2Institute of Physics, Eötvös Loránd University, 1117 Budapest, Hungary.
3National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, USA.
Reprinted with permission from AAAS

The composition of the early Solar System can be inferred from meteorites. Many elements heavier than iron were formed by the rapid neutron capture process (r-process), but the astrophysical sources where this occurred remain poorly understood. We demonstrate that the near-identical half-lives (≃15.6 million years) of the radioactive r-process nuclei iodine-129 and curium-247 preserve their ratio, irrespective of the time between production and incorporation into the Solar System. We constrain the last r-process source by comparing the measured meteoritic ratio 129I/247Cm = 438 ± 184 with nucleosynthesis calculations based on neutron star merger and magneto-rotational supernova simulations. Moderately neutron-rich conditions, often found in merger disk ejecta simulations, are most consistent with the meteoritic value. Uncertain nuclear physics data limit our confidence in this conclusion.


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