title: Recent near-Earth supernovae probed by global deposition of interstellar radioactive (60)Fe.
abstract: The rate of supernovae in our local Galactic neighbourhood within a distance of about 100 parsecs from Earth is estimated to be one every 2-4 million years, based on the total rate in the Milky Way (2.0 ± 0.7 per century). Recent massive-star and supernova activity in Earth's vicinity may be traced by radionuclides with half-lives of up to 100 million years, if trapped in interstellar dust grains that penetrate the Solar System. One such radionuclide is (60)Fe (with a half-life of 2.6 million years), which is ejected in supernova explosions and winds from massive stars. Here we report that the (60)Fe signal observed previously in deep-sea crusts is global, extended in time and of interstellar origin from multiple events. We analysed deep-sea archives from all major oceans for (60)Fe deposition via the accretion of interstellar dust particles. Our results reveal (60)Fe interstellar influxes onto Earth at 1.5-3.2 million years ago and at 6.5-8.7 million years ago. The signal measured implies that a few per cent of fresh (60)Fe was captured in dust and deposited on Earth. Our findings indicate multiple supernova and massive-star events during the last ten million years at distances of up to 100 parsecs.
authors.affiliation: Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University (ANU), Canberra, Australian Capital Territory 2601, Australia.
authors.forename: A
authors.initials: A
authors.lastname: Wallner
authors.affiliation: University of Vienna, Faculty of Physics-Isotope Research, VERA Laboratory, Währinger Straße 17, 1090 Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Feige
authors.affiliation: Institute of Technology, Shimizu Corporation, Tokyo 135-8530, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Kinoshita
authors.affiliation: Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Paul
authors.affiliation: Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University (ANU), Canberra, Australian Capital Territory 2601, Australia.
authors.forename: L K
authors.initials: LK
authors.lastname: Fifield
authors.affiliation: University of Vienna, Faculty of Physics-Isotope Research, VERA Laboratory, Währinger Straße 17, 1090 Vienna, Austria.
authors.forename: R
authors.initials: R
authors.lastname: Golser
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Honda
authors.affiliation: Senckenberg Collections of Natural History Dresden, GeoPlasmaLab, Königsbrücker Landstraße 159, Dresden 01109, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Linnemann
authors.affiliation: MALT (Micro Analysis Laboratory, Tandem accelerator), The University Museum, The University of Tokyo, Tokyo 113-0032, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Matsuzaki
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Helmholtz Institute for Resource Technology, 01328 Dresden, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Merchel
authors.affiliation: Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Helmholtz Institute for Resource Technology, 01328 Dresden, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Rugel
authors.affiliation: Department of Nuclear Physics, Research School of Physics and Engineering, The Australian National University (ANU), Canberra, Australian Capital Territory 2601, Australia.
authors.forename: S G
authors.initials: SG
authors.lastname: Tims
authors.affiliation: University of Vienna, Faculty of Physics-Isotope Research, VERA Laboratory, Währinger Straße 17, 1090 Vienna, Austria.
authors.forename: P
authors.initials: P
authors.lastname: Steier
authors.affiliation: Graduate School of Integrated Basic Sciences, Nihon University, Tokyo 156-8550, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yamagata
authors.affiliation: University of Vienna, Faculty of Physics-Isotope Research, VERA Laboratory, Währinger Straße 17, 1090 Vienna, Austria.
authors.forename: S R
authors.initials: SR
authors.lastname: Winkler