Publication Date:
2016-04-15
Description:
The signature of (60)Fe in deep-sea crusts indicates that one or more supernovae exploded in the solar neighbourhood about 2.2 million years ago. Recent isotopic analysis is consistent with a core-collapse or electron-capture supernova that occurred 60 to 130 parsecs from the Sun. Moreover, peculiarities in the cosmic ray spectrum point to a nearby supernova about two million years ago. The Local Bubble of hot, diffuse plasma, in which the Solar System is embedded, originated from 14 to 20 supernovae within a moving group, whose surviving members are now in the Scorpius-Centaurus stellar association. Here we report calculations of the most probable trajectories and masses of the supernova progenitors, and hence their explosion times and sites. The (60)Fe signal arises from two supernovae at distances between 90 and 100 parsecs. The closest occurred 2.3 million years ago at present-day galactic coordinates l = 327 degrees , b = 11 degrees , and the second-closest exploded about 1.5 million years ago at l = 343 degrees , b = 25 degrees , with masses of 9.2 and 8.8 times the solar mass, respectively. The remaining supernovae, which formed the Local Bubble, contribute to a smaller extent because they happened at larger distances and longer ago ((60)Fe has a half-life of 2.6 million years). There are uncertainties relating to the nucleosynthesis yields and the loss of (60)Fe during transport, but they do not influence the relative distribution of (60)Fe in the crust layers, and therefore our model reproduces the measured relative abundances very well.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Breitschwerdt, D -- Feige, J -- Schulreich, M M -- de Avillez, M A -- Dettbarn, C -- Fuchs, B -- England -- Nature. 2016 Apr 7;532(7597):73-6. doi: 10.1038/nature17424.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Astronomy and Astrophysics, Berlin Institute of Technology, Hardenbergstrasse 36, 10623 Berlin, Germany. ; Department of Mathematics, University of Evora, Rua Romao Ramalho 59, 7000 Evora, Portugal. ; Astronomisches Rechen-Institut, Zentrum fur Astronomie der Universitat Heidelberg, Monchhofstrasse 12-14, 69120 Heidelberg, Germany.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27078566" target="_blank"〉PubMed〈/a〉
Print ISSN:
0028-0836
Electronic ISSN:
1476-4687
Topics:
Biology
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Chemistry and Pharmacology
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Medicine
,
Natural Sciences in General
,
Physics
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