Comet encounters and carbon 14

David Eichler, David Mordecai

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


The 14C production of shock-accelerated particles is calculated in terms of the total energy released in energetic particles. The recently reported 1.2% jump in the 14C content of the atmosphere in the year C.E. 775, it is found, would require ≳ 1034 erg in energetic particles, less than first estimates but far more than any known solar flare on record. It is noted that the superflare from a large comet (comparable to C/Hale-Bopp) colliding with the sun could produce shock-accelerated GeV cosmic rays in the solar corona and/or solar wind, and possibly account for the C.E. 775 event. Several additional predictions of cometary encounters with the sun and other stars may be observable in the future.

Original languageEnglish
Article numberL27
JournalAstrophysical Journal Letters
Issue number2
StatePublished - 20 Dec 2012


  • Sun: flares
  • acceleration of particles
  • comets: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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