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A signature of cosmic-ray increase in ad 774–775 from tree rings in Japan


Increases in 14C concentrations in tree rings could be attributed to cosmic-ray events1,2,3,4,5,6,7, as have increases in 10Be and nitrate in ice cores8,9. The record of the past 3,000 years in the IntCal09 data set10, which is a time series at 5-year intervals describing the 14C content of trees over a period of approximately 10,000 years, shows three periods during which 14C increased at a rate greater than 3‰ over 10 years. Two of these periods have been measured at high time resolution, but neither showed increases on a timescale of about 1 year (refs 11 and 12). Here we report 14C measurements in annual rings of Japanese cedar trees from ad 750 to ad 820 (the remaining period), with 1- and 2-year resolution. We find a rapid increase of about 12‰ in the 14C content from ad 774 to 775, which is about 20 times larger than the change attributed to ordinary solar modulation. When averaged over 10 years, the data are consistent with the decadal IntCal 14C data from North American and European trees13. We argue that neither a solar flare nor a local supernova is likely to have been responsible.

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Figure 1: Measured radiocarbon content and comparison with IntCal98.
Figure 2: Comparison of our data with a four-box carbon cycle simulation.

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  1. Konstantinov, B. P. & Kocharov, G. E. Astrophysical Events and Radiocarbon (NASA-CR-77812, ST-CMG-AC-10430, 1965)

    Google Scholar 

  2. Damon, P. E., Kaimei, D., Kocharov, G. E., Mikheeva, I. B. & Peristykh, A. N. Radiocarbon production by the gamma-ray component of supernova explosions. Radiocarbon 37, 599–604 (1995)

    Article  CAS  Google Scholar 

  3. Damon, P. E. & Peristykh, A. N. Radiocarbon calibration and application to geophysics, solar physics, and astrophysics. Radiocarbon 42, 137–150 (2000)

    Article  CAS  Google Scholar 

  4. Menjo, H. et al. in Proc. 29th Int. Cosmic Ray Conf. Vol. 2 (ed. Acharya, B. S. ) 357–360 (Tata Institute of Fundamental Research, Mumbai, 2005)

    Google Scholar 

  5. Usoskin, I. G., Solanki, S. K., Kovaltsov, G. A., Beer, J. & Kromer, B. Solar proton events in cosmogenic isotope data. Geophys. Res. Lett. 33, L08107, (2006)

  6. Brakenridge, G. R. Core-collapse supernovae and the Younger Dryas/terminal Rancholabrean extinctions. Icarus 215, 101–106 (2011)

    Article  ADS  CAS  Google Scholar 

  7. LaViolette, P. A. Evidence for a solar flare cause of the Pleistocene mass extinction. Radiocarbon 53, 303–323 (2011)

    Article  CAS  Google Scholar 

  8. McCracken, K. G., Dreschhoff, G. A. M., Zeller, E. J., Smart, D. F. & Shea, M. A. Solar cosmic ray events for the period 1561–1994 1. Identification in polar ice, 1561–1950. J. Geophys. Res. 106, 21585–21598 (2001)

    Article  ADS  Google Scholar 

  9. Motizuki, Y. et al. An Antarctic ice core recording both supernovae and solar cycles. Preprint at (2009)

  10. Reimer, P. J. et al. IntCal09 and marin09 radiocarbon age calibration curves, 0–50,000 years cal BP. Radiocarbon 51, 1111–1150 (2009)

    Article  CAS  Google Scholar 

  11. Stuiver, M., Reimer, P. J. & Braziunas, T. F. High-precision radiocarbon age calibration for terrestrial and marine samples. Radiocarbon 40, 1127–1151 (1998)

    Article  CAS  Google Scholar 

  12. Takahashi, Y. et al. in Proc. 30th Int. Cosmic Ray Conf. Vol. 1 (ed. Caballero, R. ) 673–676 (Universitad nacional autonoma de Mexico, 2007)

    Google Scholar 

  13. Stuiver, M. et al. INTCAL98 Radiocarbon age calibration, 24,000–0 cal BP. Radiocarbon 40, 1041–1083 (1998)

    Article  CAS  Google Scholar 

  14. Horiuchi, K. et al. Ice core record of 10Be over the past millennium from Dome Fuji, Antarctica: a new proxy record of past solar activity and a powerful tool for stratigraphic dating. Quat. Geochronol. 3, 253–261 (2008)

    Article  Google Scholar 

  15. Nakamura, T., Nakai, N. & Ohishi, S. Applications of environmental 14C measured by AMS as a carbon tracer. Nucl. Instrum. Methods B 29, 355–360 (1987)

    Article  ADS  Google Scholar 

  16. Masarik, J. & Beer, J. An updated simulation of particle fluxes and cosmogenic nuclide production in the Earth’s atmosphere. J. Geophys. Res. 114, D11103, (2009)

  17. GEANT4.

  18. Burrows, A. Supernova explosions in the Universe. Nature 403, 727–733 (2000)

    Article  ADS  CAS  Google Scholar 

  19. Iyudin, A. F. et al. Emission from 44Ti associated with a previously unknown Galactic supernova. Nature 396, 142–144 (1998)

    Article  ADS  CAS  Google Scholar 

  20. Katsuda, S., Tsunemi, H. & Mori, K. Is Vela Jr. a young supernova remnant? Adv. Space Res. 43, 895–899 (2009)

    Article  ADS  CAS  Google Scholar 

  21. Telezhinsky, I. A new model for Vela Jr. supernova remnant. Astropart. Phys. 31, 431–436 (2009)

    Article  ADS  Google Scholar 

  22. Sato, T., Yasuda, H., Niita, K., Endo, A. & Sihver, L. Development of PARMA: PHITS based Analytical Radiation Model in the Atmosphere. Radiat. Res. 170, 244–259 (2008)

    Article  ADS  CAS  Google Scholar 

  23. Baker, D. N. in Space Weather: The Physics Behind a Slogan (eds Scherer, K., Fichtner, H., Heber, B. & Mall, U. ) 3 (Lecture Notes in Physics, Vol. 656, Springer, 2004)

    Book  Google Scholar 

  24. Schaefer, B. E., King, J. R. & Deliyannis, C. P. Superflares on ordinary solar-type stars. Astrophys. J. 529, 1026–1030 (2000)

    Article  ADS  Google Scholar 

  25. Lanza, A. F. Hot Jupiters and stellar magnetic activity. Astron. Astrophys. 487, 1163–1170 (2008)

    Article  ADS  CAS  Google Scholar 

  26. Ip, W. H., Kopp, A. & Hu, J. H. On the star-magnetosphere interaction of close-in exoplanets. Astrophys. J. 602, L53–L56 (2004)

    Article  ADS  Google Scholar 

  27. Willson, L. A. & Struck, C. Hot flashes on Miras? J. Am. Assoc. Variable Star. Obs. 30, 23–25 (2001)

    ADS  Google Scholar 

  28. Struck, C., Cohanim, B. E. & Wilson, L. A. Continuous and burst-like accretion on to substellar companions in Mira winds. Mon. Not. R. Astron. Soc. 347, 173–186 (2004)

    Article  ADS  Google Scholar 

  29. Cuntz, M., Saar, S. H. & Musielak, Z. E. On stellar activity enhancement due to interactions with extrasolar giant planets. Astrophys. J. 533, L151–L154 (2000)

    Article  ADS  CAS  Google Scholar 

  30. Stuiver, M. & Polach, H. A. Discussion: reporting of 14C data. Radiocarbon 19, 355–363 (1977)

    Article  Google Scholar 

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We thank K. Kimura for providing our tree B sample and dating the sample tree rings by dendrochronology. We also thank Y. Itow and Y. Matsubara for commenting on our manuscript. This work was partly supported by Grants-in-Aid for Scientific Research (B:22340144) provided by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) of Japan.

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Authors and Affiliations



K.M. conducted the research. F.M. prepared samples. T.N. measured 14C content by AMS at Nagoya University. F.M., K.M. and K.N. discussed the result. F.M. prepared the manuscript. K.M. and T.N. commented on the manuscript.

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Correspondence to Fusa Miyake.

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The authors declare no competing financial interests.

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Miyake, F., Nagaya, K., Masuda, K. et al. A signature of cosmic-ray increase in ad 774–775 from tree rings in Japan. Nature 486, 240–242 (2012).

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