NTRS - NASA Technical Reports Server

Back to Results
Dynamic evolution of the source volumes of gradual and impulsive solar flare emissionsThis study compares flare source volumes inferred from impulsive hard X-rays and microwaves with those derived from density sensitive soft X-ray line ratios in the O VII spectrum. The data for this study were obtained with the SMM Hard X-ray Burst Spectrometer, Earth-based radio observatories, and the SOLEX-B spectrometer on the P78-1 satellite. Data were available for the flares of 1980 April 8, 1980 May 9, and 1981 February 26. The hard X-ray/microwave source volume is determined under the assumption that the same electron temperature or power law index characterizes both the source of hard X-rays and the source of microwaves. The O VII line ratios yield the density and volume of the 2 x 10 to the 6th K plasma. For all three flares, the O VII source volume is found to be smallest at the beginning of the flare, near the time when the impulsive hard X-ray/microwave volume reaches its first maximum. At this time, the O VII volume is three to four orders of magnitude smaller than that inferred from the hard X-ray/microwave analysis. Subsequently, the O VII source volume increases by one or two orders of magnitude then remains almost constant until the end of the flare when it apparently increases again.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Bruner, M. E. (Lockheed Research Laboratories Palo Alto, CA, United States)
Crannell, C. J. (Lockheed Missiles and Space Co. Palo Alto, CA, United States)
Goetz, F. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Magun, A. (Bern, Universitaet Switzerland)
Mckenzie, D. L. (Aerospace Corp. Space Sciences Laboratory, Los Angeles, CA, United States)
Date Acquired
August 14, 2013
Publication Date
November 1, 1988
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 334
ISSN: 0004-637X
Subject Category
Funding Number(s)
Distribution Limits