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The mean ionic charge state of solar energetic Fe ions above 200 MeV per nucleonWe have analyzed the geomagnetic transmission of solar energetic Fe ions at approximately 200-600 MeV per nucleon during the great solar energetic particle (SEP) events of 1989 September-October. By comparing fluences from the Chicago charged-particle telescope on IMP-8 in interplanetary space and from NRL's Heavy Ions in Space (HIIS) experiment aboard the Long Duration Exposure Facility (LDEF) in low-Earth orbit, we obtain a mean ionic charge (Q(sub 3)) = 14.2 +/- 1.4. This result is significantly lower than (Q) observed at approximately 1 MeV per nucleon in impulsive, He-3 rich SEP events, indicating that neither acceleration at the flare site nor flare-heated plasma significantly contributes to the high-energy Fe ions we observe. But it agrees well with the (Q) observed in gradual SEP events at approximately 1 MeV per nucleon, in which ions are accelerated by shocks driven by fast coronal mass ejections, and hence shows that particles are accelerated to very high energies in this way. We also note apparent differences between solar wind and SEP charge state distributions, which may favor a coronal (rather than solar wind) seed population or may suggest additional ionization in the ambient shock-region plasma.
Document ID
19950054424
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tylka, A. J.
(Naval Research Laboratory, Washington, DC United States)
Boberg, P. R.
(Naval Research Laboratory, Washington, DC United States)
Adams, J. H., Jr.
(Naval Research Laboratory, Washington, DC United States)
Beahm, L. P.
(Naval Research Laboratory, Washington, DC United States)
Dietrich, W. F.
(University of Chicago, Chicago, IL United States)
Kleis, T.
(George Mason University Fairfax, VA, United States)
Date Acquired
August 16, 2013
Publication Date
May 10, 1995
Publication Information
Publication: Astrophysical Journal, Part 2 - Letters
Volume: 444
Issue: 2
ISSN: 0004-637X
Subject Category
Solar Physics
Accession Number
95A86023
Funding Number(s)
CONTRACT_GRANT: NAG5-706
CONTRACT_GRANT: NASA ORDER W-18409
Distribution Limits
Public
Copyright
Other

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