Accelerated Particle Composition and Energetics and Ambient Abundances from Gamma-Ray Spectroscopy of the 1991 June 4 Solar Flare
NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH
Pagination or Media Count:
The Oriented Scintillation Spectrometer Experiment OSSE on board the COMPTON Gamma Ray Observatory observed the 1991 June 4 X12 solar flare, one of the most intense nuclear gamma-ray line flares observed to date. Using these OSSE observations, we have derived time profiles of the various components of gamma-ray emission and obtained information about the accelerated particle spectra and composition and about the ambient plasma at the flare site. The main results are 1 the nuclear reactions associated with the impulsive phase of the are continued for at least 2 hours and resulted from ions that were probably continuously accelerated rather than impulsively accelerated and trapped 2 the total energy in these accelerated ions exceeded the energy in 0.1 MeV electrons 3 the accelerated alphaproton ratio was closer to 0.5 than to 0.1 4 there is evidence for a decrease of the accelerated heavy ion-to-proton ratio as the are progressed 5 there is evidence for a temporal change in the composition of the flare plasma 6 the ratio of electron bremsstrahlung to the flux in narrow gamma-ray lines decreased as the flare progressed 7 the high-energy 16 MeV component of the electron spectrum was much more impulsive than the lower-energy MeV component 8 a model-dependent upper limit of 2.3 x 10exp -5 was obtained for the photospheric 3HeH abundance ratio and 9 energetic ions may have been present for several hours prior to and following the impulsive phase of the flare.
- Nuclear Physics and Elementary Particle Physics