Time-resolved 2-million-year-old supernova activity discovered in Earth's microfossil record
Abstract
Massive stars, which terminate their evolution in a cataclysmic explosion called a type-II supernova, are the nuclear engines of galactic nucleosynthesis. Among the elemental species known to be produced in these stars, the radioisotope 60Fe stands out: This radioisotope has no natural, terrestrial production mechanisms; thus, a detection of 60Fe atoms within terrestrial reservoirs is proof for the direct deposition of supernova material within our solar system. We report, in this work, the direct detection of live 60Fe atoms in biologically produced nanocrystals of magnetite, which we selectively extracted from two Pacific Ocean sediment cores. We find that the arrival of supernova material on Earth coincides with the lower Pleistocene boundary (2.7 Ma) and that it terminates around 1.7 Ma.
- Publication:
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Proceedings of the National Academy of Science
- Pub Date:
- August 2016
- DOI:
- 10.1073/pnas.1601040113
- arXiv:
- arXiv:1710.09573
- Bibcode:
- 2016PNAS..113.9232L
- Keywords:
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- accelerator mass spectrometry;
- magnetofossils;
- supernova;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Figures from the Supplementary Information are not included due to file size restrictions. Download the, now open access, original article for those details (see doi)