Cosmic ray event in 994 C.E. recorded in radiocarbon from Danish oak

A. Fogtmann-Schulz*, S. M. Østbø, Sabrina G. B. Nielsen, J. Olsen, C. Karoff, M. F. Knudsen

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

30 Citations (Scopus)

Abstract

We present measurements of radiocarbon in annual tree rings from the time period 980-1006 Common Era (C.E.), hereby covering the cosmic ray event in 994 C.E. The new radiocarbon record from Danish oak is based on both earlywood and latewood fractions of the tree rings, which makes it possible to study seasonal variations in 14C production. The measurements show a rapid increase of ∼10‰ from 993 to 994 C.E. in latewood, followed by a modest decline and relatively high values over the ensuing ∼10 years. This rapid increase occurs from 994 to 995 C.E. in earlywood, suggesting that the cosmic ray event most likely occurred during the period between April and June 994 C.E. Our new record from Danish oak shows strong agreement with existing Δ14C records from Japan, thus supporting the hypothesis that the 994 C.E. cosmic ray event was uniform throughout the Northern Hemisphere and therefore can be used as an astrochronological tie point to anchor floating chronologies of ancient history.

Original languageEnglish
JournalGeophysical Research Letters
Volume44
Issue16
Pages (from-to)8621–8628
Number of pages8
ISSN0094-8276
DOIs
Publication statusPublished - 28 Aug 2017

Keywords

  • radiocarbon
  • tree rings
  • Miyake event
  • astrochronology
  • solar proton event
  • space environment
  • TREE-RINGS
  • AD 774-775
  • CELLULOSE PREPARATION
  • ISOTOPE ANALYSIS
  • C-14 PRODUCTION
  • NEW-ZEALAND
  • INCREASE
  • WOOD
  • CHRONOLOGY

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