Abundance of live 244Pu in deep-sea reservoirs on Earth points to rarity of actinide nucleosynthesis
Abstract
Half of the heavy elements including all actinides are produced in r-process nucleosynthesis, whose sites and history remain a mystery. If continuously produced, the Interstellar Medium is expected to build-up a quasi-steady state of abundances of short-lived nuclides (with half-lives ≤100 My), including actinides produced in r-process nucleosynthesis. Their existence in today’s interstellar medium would serve as a radioactive clock and would establish that their production was recent. In particular 244Pu, a radioactive actinide nuclide (half-life=81 My), can place strong constraints on recent r-process frequency and production yield. Here we report the detection of live interstellar 244Pu, archived in Earth’s deep-sea floor during the last 25 My, at abundances lower than expected from continuous production in the Galaxy by about 2 orders of magnitude. This large discrepancy may signal a rarity of actinide r-process nucleosynthesis sites, compatible with neutron-star mergers or with a small subset of actinide-producing supernovae.
- Publication:
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Nature Communications
- Pub Date:
- January 2015
- DOI:
- 10.1038/ncomms6956
- arXiv:
- arXiv:1509.08054
- Bibcode:
- 2015NatCo...6.5956W
- Keywords:
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- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Nature Communications 6:5956, 2015