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The composition of heavy ions in solar energetic particle eventsRecent advances in determining the elemental, charge state, and isotopic composition of or approximate to 1 to or approximate to 20 MeV per nucleon ions in solar energetic particle (SEP) events and outline our current understanding of the nature of solar and interplanetary processes which may explain the observations. Average values of relative abundances measured in a large number of SEP events were found to be roughly energy independent in the approx. 1 to approx. 20 MeV per nucleon range, and showed a systematic deviation from photospheric abundances which seems to be organized in terms of the first ionization potential of the ion. Direct measurements of the charge states of SEPs revealed the surprisingly common presence of energetic He(+) along with heavy ion with typically coronal ionization states. High resolution measurements of isotopic abundance ratios in a small number of SEP events showed these to be consistent with the universal composition except for the puzzling overabundance of the SEP(22)Ne/(20)Ne relative to this isotopes ratio in the solar wind. The broad spectrum of observed elemental abundance variations, which in their extreme result in composition anomalies characteristic of (3)He rich, heavy ion rich and carbon poor SEP events, along with direct measurements of the ionization states of SEPs provided essential information on the physical characteristics of, and conditions in the source regions, as well as important constraints to possible models for SEP production. Previously announced in STAR as N83-20886
Document ID
19840056355
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Fan, C. Y.
(Arizona, University Tucson, AZ, United States)
Gloeckler, G.
(Maryland, University College Park, MD, United States)
Hovestadt, D.
(Max-Planck-Institut fuer Physik und Astrophysik Garching, Germany)
Date Acquired
August 12, 2013
Publication Date
June 1, 1984
Publication Information
Publication: Space Science Reviews
Volume: 38
ISSN: 0038-6308
Subject Category
Solar Physics
Accession Number
84A39142
Funding Number(s)
CONTRACT_GRANT: NAGW-101
CONTRACT_GRANT: NGR-21-002-224
CONTRACT_GRANT: NGR-03-002-107
CONTRACT_GRANT: NGR-21-002-316
Distribution Limits
Public
Copyright
Other

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