A signature of cosmic-ray increase in AD 774-775 from tree rings in Japan - PubMed (original) (raw)

. 2012 Jun 3;486(7402):240-2.

doi: 10.1038/nature11123.

Affiliations

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

Fusa Miyake et al. Nature. 2012.

Abstract

Increases in (14)C concentrations in tree rings could be attributed to cosmic-ray events, as have increases in (10)Be and nitrate in ice cores. The record of the past 3,000 years in the IntCal09 data set, which is a time series at 5-year intervals describing the (14)C content of trees over a period of approximately 10,000 years, shows three periods during which (14)C 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 (14)C 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 (14)C 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 (14)C data from North American and European trees. We argue that neither a solar flare nor a local supernova is likely to have been responsible.

PubMed Disclaimer

Comment in

Similar articles

Cited by

References

    1. Nature. 2000 Feb 17;403(6771):727-33 - PubMed
    1. Astrophys J. 2000 Apr 20;533(2):L151-L154 - PubMed
    1. Radiat Res. 2008 Aug;170(2):244-59 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources