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Multiradionuclide evidence for the solar origin of the cosmic-ray events of AD 774/5 and 993/4
Lund Univ, Dept Geol Quaternary Sci, S-22362 Lund, Sweden..
Lund Univ, Dept Geol Quaternary Sci, S-22362 Lund, Sweden..
Lund Univ, Dept Geol Quaternary Sci, S-22362 Lund, Sweden..
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL. United Arab Emirates Univ, Dept Geol, Al Ain 17551, U Arab Emirates..
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2015 (English)In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, 8611Article in journal (Refereed) PublishedText
Abstract [en]

The origin of two large peaks in the atmospheric radiocarbon (C-14) concentration at AD 774/5 and 993/4 is still debated. There is consensus, however, that these features can only be explained by an increase in the atmospheric C-14 production rate due to an extraterrestrial event. Here we provide evidence that these peaks were most likely produced by extreme solar events, based on several new annually resolved Be-10 measurements from both Arctic and Antarctic ice cores. Using ice core Cl-36 data in pair with Be-10, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100MeV. These results imply that the larger of the two events (AD 774/5) was at least five times stronger than any instrumentally recorded solar event. Our findings highlight the importance of studying the possibility of severe solar energetic particle events.

Place, publisher, year, edition, pages
2015. Vol. 6, 8611
National Category
Other Natural Sciences
URN: urn:nbn:se:uu:diva-269996DOI: 10.1038/ncomms9611ISI: 000364934200013PubMedID: 26497389OAI: diva2:885581
Swedish Research Council, DNR2013-8421
Available from: 2015-12-19 Created: 2015-12-19 Last updated: 2016-02-11Bibliographically approved

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