Time resolved 2 million year old supernova activity discovered in Earth's microfossil record

Abstract

Massive stars, which terminate their evolution as core collapse supernovae, are theoretically predicted to eject more than 1E-5 solar masses of the radioisotope 60Fe. If such an event occurs sufficiently close to our solar system, traces of the supernova debris could be deposited on Earth. Herein, we report a time resolved 60Fe signal residing, at least partially, in a biogenic reservoir. Using accelerator mass spectrometry, this signal was found through the direct detection of live 60Fe atoms contained within secondary iron oxides, among which are magnetofossils, the fossilized chains of magnetite crystals produced by magnetotactic bacteria. The magnetofossils were chemically extracted from two Pacific Ocean sediment drill cores. Our results show that the 60Fe signal onset occurs around 2.6 Ma to 2.8 Ma, near the lower Pleistocene boundary, terminates around 1.7 Ma, and peaks at about 2.2 Ma.

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)

References in corpus (5)

• The nucleosynthesis of Al26 and Fe60 in solar metallicity stars extending in mass from 11 to 120 Msun: the hydrostatic and explosive contributions
• Rapid formation of large dust grains in the luminous supernova SN 2010jl
• Evaluation of three methods for calculating statistical significance when incorporating a systematic uncertainty into a test of the background-only hypothesis for a Poisson process
• Search for supernova-produced 60Fe in a marine sediment
• Discovery Prospects for a Supernova Signature of Biogenic Origin

Cited by in corpus (4)

• Photobiological effects at Earth's surface following a 50 pc Supernova
• From cosmic explosions to terrestrial fires?
• Stellar encounters with giant molecular clouds
• The Link Between the Local Bubble and Radioisotopic Signatures on Earth