Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4

F. Mekhaldi; Raimund Muscheler; Florian Adolphi; Ala Aldahan; J.R. McConnell; G. Possnert; Michael Sigl; Anders Svensson; Hans-Arno Synal; K.C. Welten; T. E. Woodruff

doi:10.1038/ncomms9611

Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4

F. Mekhaldi, Raimund Muscheler, Florian Adolphi, Ala Aldahan, J.R. McConnell, G. Possnert, Michael Sigl, Anders Svensson, Hans-Arno Synal, K.C. Welten, T. E. Woodruff

Physics of Ice, Climate and Earth

112 Citations (Scopus)

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Abstract

The origin of two large peaks in the atmospheric radiocarbon (14 C) 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 14 C 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 10 Be measurements from both Arctic and Antarctic ice cores. Using ice core 36 Cl data in pair with 10 Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. 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.

Original language	English
Article number	8611
Journal	Nature Communications
Volume	6
ISSN	2041-1723
DOIs	https://doi.org/10.1038/ncomms9611
Publication status	Published - 26 Oct 2015

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title = "Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4",

abstract = "The origin of two large peaks in the atmospheric radiocarbon (14 C) 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 14 C 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 10 Be measurements from both Arctic and Antarctic ice cores. Using ice core 36 Cl data in pair with 10 Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. 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.",

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T1 - Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4

AU - Mekhaldi, F.

AU - Muscheler, Raimund

AU - Adolphi, Florian

AU - Aldahan, Ala

AU - McConnell, J.R.

AU - Possnert, G.

AU - Sigl, Michael

AU - Svensson, Anders

AU - Synal, Hans-Arno

AU - Welten, K.C.

AU - Woodruff, T. E.

PY - 2015/10/26

Y1 - 2015/10/26

N2 - The origin of two large peaks in the atmospheric radiocarbon (14 C) 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 14 C 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 10 Be measurements from both Arctic and Antarctic ice cores. Using ice core 36 Cl data in pair with 10 Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. 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.

AB - The origin of two large peaks in the atmospheric radiocarbon (14 C) 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 14 C 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 10 Be measurements from both Arctic and Antarctic ice cores. Using ice core 36 Cl data in pair with 10 Be, we further show that these solar events were characterized by a very hard energy spectrum with high fluxes of solar protons with energy above 100 MeV. 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.

U2 - 10.1038/ncomms9611

DO - 10.1038/ncomms9611

M3 - Journal article

SN - 2041-1723

VL - 6

JO - Nature Communications

JF - Nature Communications

M1 - 8611

ER -

Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4

Abstract

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