Dynamic evolution of the source volumes of gradual and impulsive solar flare emissions

Journal Article · Tue Nov 01 04:00:00 EST 1988 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/166854· OSTI ID:6535053

Bruner, M E; Crannell, C J; Goetz, F; Magun, A; Mckenzie, D L

This 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. 29 references.

• Research Organization: Lockheed Research Laboratories, Palo Alto, CA (USA); NASA, Goddard Space Flight Center, Greenbelt, MD (USA); Bern Universitaet (Switzerland); Aerospace Corp., Los Angeles, CA (USA)
• OSTI ID: 6535053
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 334; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics & Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATMOSPHERES
CHROMOSPHERE
ELECTROMAGNETIC RADIATION
ELECTRON TEMPERATURE
EVAPORATION
HARD X RADIATION
IONIZING RADIATIONS
MEASURING INSTRUMENTS
MICROWAVE RADIATION
PHASE TRANSFORMATIONS
PLASMA
RADIATION SOURCES
RADIATIONS
SOFT X RADIATION
SOLAR ACTIVITY
SOLAR ATMOSPHERE
SOLAR FLARES
SOLAR RADIATION
SPECTROMETERS
STEADY-STATE CONDITIONS
STELLAR RADIATION
X RADIATION