Abundances of heavy and ultraheavy ions in 3He-rich solar flares

G. M. Mason, J. E. Mazur, J. R. Dwyer, J. R. Jokipii, R. E. Gold, S. M. Krimigis

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112 Scopus citations

Abstract

We have surveyed 3He-rich solar energetic particle (SEP) events over the period 1997 September-2003 April in order to characterize abundances of heavy ions near 400 keV nucleon-1. The first part of the study focuses on 20 distinct SEP events that show the previously observed pattern in which, relative to O, heavy ions through Fe are enriched, with the enrichment increasing with mass. We find that these enrichments are well correlated such that 3He-rich SEP events with high Fe/C also show larger enrichments in other heavy ions. Ultraheavy (UH; taken as 78-220 amu) ions are routinely seen in these events with abundance enhancements correlating with Fe/C but with even larger flare-to-flare variations. In one event with unusually little interplanetary scattering, we are able to estimate the time of heavy- and UH-ion injections at the Sun and find them to be simultaneous. The second part of the study sums up many impulsive-event time periods in order to construct a mass histogram of UH nuclei; this histogram shows broad mass peaks similar to those in compilations of solar system abundances. In this summed period, relative to O, the average enhancement of heavy nuclei increases with mass with values of ∼7 for Fe, ∼40 for mass 78-100 amu, ∼120 for mass 125-150 amu, and ∼215 for 180-220 amu. The maximum UH enhancements seen in the most-enriched events are at least a factor of 5 larger. The enhancements are approximately proportional to the particle charge-to-mass ratio raised to a power, as seen previously in large, shock-associated SEP events.

Original languageEnglish (US)
Pages (from-to)555-564
Number of pages10
JournalAstrophysical Journal
Volume606
Issue number1 I
DOIs
StatePublished - May 1 2004

Keywords

  • Acceleration of particles
  • Cosmic rays
  • Shock waves
  • Solar wind
  • Sun: abundances
  • Sun: flares

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Mason, G. M., Mazur, J. E., Dwyer, J. R., Jokipii, J. R., Gold, R. E., & Krimigis, S. M. (2004). Abundances of heavy and ultraheavy ions in 3He-rich solar flares. Astrophysical Journal, 606(1 I), 555-564. https://doi.org/10.1086/382864