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774–775 carbon-14 spike

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The774–775 carbon-14 spikeis an observed increase of around 1.2% in the concentration of the radioactivecarbon-14isotope intree ringsdated to 774 or 775CE,which is about 20 times higher than the normal year-to-year variation of radiocarbon in the atmosphere. It was discovered during a study ofJapanese cedartree-rings, with the year of occurrence determined throughdendrochronology.[1]A surge inberylliumisotope10
Be,detected in Antarctic ice cores, has also been associated with the 774–775 event.[2]The 774–775 CE carbon-14 spike is one of severalMiyake eventsand it produced the largest and most rapid rise in carbon-14 ever recorded.[3][4]

The event appears to have been global, with the same carbon-14 signal found in tree rings fromGermany,Russia,theUnited States,Finland,andNew Zealand.[2][5][6]

Thecarbon-14spike around 774. Colored dots are measurements in Japanese (M12) and German (oak) trees; black lines are the modeled profile corresponding to the instant production of carbon-14.[2]

The signal exhibits a sharp increase of around 1.2% followed by a slow decline, which is consistent with an instant production of carbon-14 in the atmosphere,[2]indicating that the event was short in duration. The globally averaged production ofcarbon-14for this event is(1.3 ± 0.2) × 108atoms/cm2.[2][7][8]

Hypotheses[edit]

Several possible causes of the event have been considered.

TheAnglo-Saxon Chroniclerecorded "a red crucifix, after sunset", which has been variously hypothesised to have been asupernova[9]or theaurora borealis.[2][10]

Annus Domini (the year of the Lord) 774. This year theNorthumbriansbanished their king,Alred,fromYorkat Easter-tide; and choseEthelred, the son of Mull,for their lord, who reigned four winters. This year also appeared in the heavens a red crucifix, after sunset; theMerciansand the men ofKentfought atOtford;and wonderful serpents were seen in theland of the South-Saxons.

— Anglo-Saxon Chronicle[9]

In China, there is only one clear reference to an aurora in the mid-770s, on 12 January 776.[11][12]However, an anomalous "thunderstorm" was recorded for 775.[13]

As established byIlya G. Usoskinand colleagues,[14]the current scientific paradigm[15]is that the event was caused by asolar particle event(SPE) from a very strongsolar flare,perhaps the strongest known.[16] Another proposed origin, involving agamma-ray burst,[8][17]is regarded as unlikely, because the event was also observed in isotopes10
Beand36
Cl.[16][clarification needed]

Frequency of similar events[edit]

The AD 774/75 event in view of10
Be,14
C,and36
Cl

The event of 774 is the strongest spike over the last 11,000 years in the record of cosmogenic isotopes,[18]but several other events of the same kind (Miyake events) have occurred during theHoloceneepoch.[18]The993–994 carbon-14 spikewas about 60% as strong;[19]another event occurred inc. 660 BCE.[20][21]In 2023 the strongest event yet discovered was reported, which occurred in 12,350-12,349 BC.[22]

The event of 774 did not have any significant consequences for life on Earth,[23][24]but had it happened in modern times, it might have produced catastrophic damage to modern technology, particularly to communication and space-borne navigation systems. In addition, a solar flare capable of producing the observed isotopic effect would pose considerable risk to astronauts.[25]

14
Cvariations are poorly understood, because annual-resolution measurements are available for only a few periods (such as 774–775).[26]In a 2017 study, a14
Cincrease of (2.0%) was associated with a 5480 BCE event, but it is not associated with a solar event because of its long duration, but rather to an unusually fastgrand minimumof solar activity.[26]

See also[edit]

References[edit]

  1. ^ Miyake, F.; Nagaya, K.; Masuda, K.; Nakamura, T. (2012). "A signature of cosmic-ray increase in AD 774–775 from tree rings in Japan".Nature.486(7402): 240–2.Bibcode:2012Natur.486..240M.doi:10.1038/nature11123.PMID22699615.S2CID4368820.
  2. ^abcdef Usoskin, I. G.; et al. (2013). "The AD775 cosmic event revisited: The Sun is to blame".Astronomy & Astrophysics.552(1): L3.arXiv:1302.6897.Bibcode:2013A&A...552L...3U.doi:10.1051/0004-6361/201321080.S2CID55137950.
  3. ^Reimer, Paula; et al. (August 2020)."The IntCal20 Northern Hemisphere Radiocarbon Age Calibration Curve (0–55 cal kBP)".Radiocarbon.62(4): 725–757.Bibcode:2020Radcb..62..725R.doi:10.1017/RDC.2020.41.hdl:1893/30981.S2CID216215614.
  4. ^University of Kansas (November 30, 2012)."Researcher points to Sun as likely source of eighth-century 'Charlemagne event'".
  5. ^ Jull, A.J.T.; Panyushkina, I.P.; Lange, T.E.; et al. (2014). "Excursions in the 14C record at AD 774–775 in tree rings from Russia and America".Geophys. Res. Lett.41(8): 3004–3010.Bibcode:2014GeoRL..41.3004J.doi:10.1002/2014GL059874.hdl:10150/628657.S2CID19045243.
  6. ^ Güttler, D.; Beer, J.; Bleicher, N. (2013). "The 774/775 AD event in the southern hemisphere".ETH-Zurich: Laboratory of Ion Beam Physics: Annual Report 2013.LIBRUM. p. 33.ISBN9783952403846.OCLC887695262.
  7. ^ Melott, A.L.; Thomas, B.C. (2012). "Causes of an AD 774-77514C increase ".Nature.491(7426): E1–E2.arXiv:1212.0490.Bibcode:2012Natur.491E...1M.doi:10.1038/nature11695.PMID23192153.S2CID205231715.
  8. ^ab Pavlov, A.K.; Blinov, A.V.; Konstantinov, A.N.; et al. (2013). "AD 775 pulse of cosmogenic radionuclides production as imprint of a Galactic gamma-ray burst".Mon. Not. R. Astron. Soc.435(4): 2878–2884.arXiv:1308.1272.Bibcode:2013MNRAS.435.2878P.doi:10.1093/mnras/stt1468.
  9. ^abOwano, Nancy (2012-06-30)."Red Crucifix sighting in 774 may have been supernova".Phys.org.
  10. ^Hayakawa, H. (2019). "The Celestial Sign in the Anglo-Saxon Chronicle in the 770s: Insights on Contemporary Solar Activity".Solar Physics.294(4): 42.arXiv:1903.03075.Bibcode:2019SoPh..294...42H.doi:10.1007/s11207-019-1424-8.S2CID118718677.
  11. ^Stephenson, F.R. (2015). "Astronomical evidence relating to the observed14C increases in A.D. 774–5 and 993–4 as determined from tree rings ".Advances in Space Research.55(6): 1537–45.Bibcode:2015AdSpR..55.1537S.doi:10.1016/j.asr.2014.12.014.
  12. ^Stephenson, F.R. (2019)."Do the Chinese Astronomical Records Dated AD 776 January 12/13 Describe an Auroral Display or a Lunar Halo? A Critical Re-examination"(PDF).Solar Physics.294(4): 36.arXiv:1903.06806.Bibcode:2019SoPh..294...36S.doi:10.1007/s11207-019-1425-7.
  13. ^Ya-Ting Chai & Yuan-Chuan Zou (2015). "Searching for events in Chinese ancient records to explain the increase in14C from 774–775 CE and 993–994 AD ".Research in Astronomy and Astrophysics.15(9): 1504.arXiv:1406.7306.doi:10.1088/1674-4527/15/9/007.S2CID124499827.
  14. ^Usoskin, I.G.;Kromer, B.; Ludlow, F.; Beer, J.; Friedrich, M.; Kovaltsov, G.A.; Solanki, S.K.; Wacker, L. (2013). "The AD775 cosmic event revisited: the Sun is to blame".Astronomy and AstrophysicsLetters.552:L3.arXiv:1302.6897.doi:10.1051/0004-6361/201321080.
  15. ^Usoskin, I.G.;Miyake, F.; Baroni, M.; et al. (2023). "Extreme Solar Events: Setting up a Paradigm".Space Science Reviews.219:73.doi:10.1007/s11214-023-01018-1.hdl:20.500.11850/641517.
  16. ^abMekhaldi; et al. (2015)."Multiradionuclide evidence for the solar origin of the cosmic-ray events of ᴀᴅ 774/5 and 993/4".Nature Communications.6:8611.Bibcode:2015NatCo...6.8611M.doi:10.1038/ncomms9611.PMC4639793.PMID26497389.
  17. ^ Hambaryan, V. V.; Neuhauser, R. (2013). "A Galactic short gamma-ray burst as cause for the14C peak in AD 774/5 ".Monthly Notices of the Royal Astronomical Society.430(1): 32–36.arXiv:1211.2584.Bibcode:2013MNRAS.430...32H.doi:10.1093/mnras/sts378.
  18. ^ab Usoskin, I.G.; Kovaltsov, G.A. (2012). "Occurrence of Extreme Solar Particle Events: Assessment from Historical Proxy Data".Astrophys. J.757(1): 92.arXiv:1207.5932.Bibcode:2012ApJ...757...92U.doi:10.1088/0004-637X/757/1/92.S2CID56189671.
  19. ^ Miyake, F.; Masuda, K.; Nakamura, T. (2013)."Another rapid event in the carbon-14 content of tree rings".Nature Communications.4:1748.Bibcode:2013NatCo...4.1748M.doi:10.1038/ncomms2783.PMID23612289.
  20. ^O'Hare, Paschal; et al. (2019)."Multiradionuclide evidence for an extreme solar proton event around 2,610 B.P. (~660 BC)".Proceedings of the National Academy of Sciences of the United States of America.116(13): 5961–6.Bibcode:2019PNAS..116.5961O.doi:10.1073/pnas.1815725116.PMC6442557.PMID30858311.
  21. ^Hayakawa, Hisashi; Mitsuma, Yasuyuki; Ebihara, Yusuke;Miyake, Fusa(2019)."The Earliest Candidates of Auroral Observations in Assyrian Astrological Reports: Insights on Solar Activity around 660 BCE".The Astrophysical Journal.884(1): L18.arXiv:1909.05498.Bibcode:2019ApJ...884L..18H.doi:10.3847/2041-8213/ab42e4.S2CID202565732.
  22. ^Edouard Bard; et al. (Oct 9, 2023)."A radiocarbon spike at 14 300 cal yr BP in subfossil trees provides the impulse response function of the global carbon cycle during the Late Glacial".Philosophical Transactions of the Royal Society A.381(2261).Bibcode:2023RSPTA.38120206B.doi:10.1098/rsta.2022.0206.PMC10586540.PMID37807686.
  23. ^Sukhodolov, Timofei; et al. (March 28, 2017)."Atmospheric impacts of the strongest known solar particle storm of 775 AD".Scientific Reports.7(1): 45257.Bibcode:2017NatSR...745257S.doi:10.1038/srep45257.ISSN2045-2322.PMC5368659.PMID28349934.
  24. ^ Thomas, B. C.; Melott, A. L.; Arkenberg, K. R.; Snyder, B. R. (2013). "Terrestrial effects of possible astrophysical sources of an AD 774–775 increase in14C production ".Geophysical Research Letters.40(6): 1237.arXiv:1302.1501.Bibcode:2013GeoRL..40.1237T.doi:10.1002/grl.50222.S2CID14253803.
  25. ^Townsend, L. W.; Porter, J. A.; deWet, W. C; Smith, W. J.; McGirl, N. A.; Heilbronn, L. H.; Moussa, H. M. (2016-06-01). "Extreme solar event of AD775: Potential radiation exposure to crews in deep space".Acta Astronautica.Special Section: Selected Papers from the International Workshop on Satellite Constellations and Formation Flying 2015.123:116–120.Bibcode:2016AcAau.123..116T.doi:10.1016/j.actaastro.2016.03.002.
  26. ^abMiyake, F.; Jull, A. J.; Panyushkina, I. P.; Wacker, L.; Salzer, M.; Baisan, C. H.; Lange, T.; Cruz, R.; Masuda, K.; Nakamura, T. (2017)."Large14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene ".Proceedings of the National Academy of Sciences of the United States of America.114(5): 881–4.Bibcode:2017PNAS..114..881M.doi:10.1073/pnas.1613144114.PMC5293056.PMID28100493.

External links[edit]

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