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Energy spectra of ions from impulsive solar flaresA study of the energy spectra of ions from impulsive solar flares in the 0.1-100 MeV region is reported. Most of the events studied are dominated by He and these He spectra show a persistent steepening or break above about 10 MeV resulting in an increase in the power-law spectral indices from about 2 to about 3.5 or more. Spectra of H, He-3, O, and Fe have spectral indices that are consistent with a value of about 3.5 above about 2 MeV/amu. One event, dominated by protons, shows a clear maximum in the spectrum near 1 MeV. If the rollover in the spectrum below 1 MeV is interpreted as a consequence of matter traversal in the solar atmosphere, then the source of the acceleration would lie only about 800 km above the photosphere, well below the corona. Alternative interpretations are that trapping in the acceleration region directly causes a peak in the resulting ion spectrum or that low-energy particles encounter significant additional scattering during transport from the flare.
Document ID
19920044702
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Reames, D. V.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Richardson, I. G.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wenzel, K.-P.
(ESTEC Noordwijk, Netherlands)
Date Acquired
August 15, 2013
Publication Date
March 10, 1992
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 387
ISSN: 0004-637X
Subject Category
Solar Physics
Accession Number
92A27326
Distribution Limits
Public
Copyright
Other

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