fl197.yoshimori08 Posted: 01-Mar-95 Updated: 17-Jul-95, 08-Apr-96 Events specified: Flares of 27-Oct-91 05:40 UT, 15-Nov-91 22:35 UT and 3-Dec-91 16:36 UT.
Collaboration: M.Yoshimori (yosimori@rikkyo.ac.jp), K.Morimoto, K.Suga, T.Matsuda and K.Kawabata
We observed three impulsive gamma-ray flares with different spectral characteristics, strong narrow line flare, broad line flare and continuum gamma-ray flare. We suggest that the narrow line flare of 1991 October 27 accelerated particles with the photospheric or heavy-rich composition, the broad line flare of 1991 November 15 accelerated particles with the extremely proton-poor or heavy-rich composition, and the continuum gamma-ray flare selectively accelerated electrons to relativistic energies. The Yohkoh gamma-ray observations indicate that the composition of the accelerated particles largely varies from flare to flare. Particle accleration processes are discussed on the basis of the gamma-ray spectra and the flare-particle composition.
Required Observations: Gamma-ray spectra and light curves of the 1991 October 27, November 15 and December 3 flares.
Update 08-Apr-96
We have reached the goal of the proposal fl197 updated 17-July-95.
Title: "Spectral Characteristics of Solar Gamma-Ray Flares "
Authors: M.Yoshimori, K.Morimoto, K.Suga, T.Matsuda and K.Kawabata
This paper was published in Proc. of 24th International Cosmic Ray Conference vol.3 (1995) 102.
Abstract
Yohkoh observed three gamma-ray flares with different spectral characteristics, strong narrow line flare, broad line flare and continuum gamma-ray flare. We discuss the possibility that spectral charactristics largely vary from flare to flare and conclude that the spectral variations are due to high variabilities in the abundances of accelerated particles. This is supported from direct observations of the abundances of solar energetic particles in interplanetary space. When the abundances of accelerated particles are coronal and heavy-rich, the strong narrow gamma-ray lines and broad gamma-ray lines are produced. When electrons are selectively accelerated, the strong bremstraklung continuum is produced.
Update 17-Jul-95
Yohkoh observed three gamma-ray flares with different spectral characteristics, strong narrow line flare, broad line flare and continuum gamma-ray flare. We discuss the abundances of accelerated particles in the gamma-ray flares on the basis of the gamma-ray spectral characteristics. The abundances of accelerated particles were known to vary largely from flare to flare. The abundances of strong narrow line flare is coronal and those of the broad line flare is extreamly heavy rich, while the continuum gamma-ray flare selectively accelerates electrons to relativistic energies.
This paper was presented in the IAU Colloquium #153 (Makuhari, May 22 -26, 1995) and is presented in the 24th International Cosmic Ray Conference (Rome, pmAug.27 - Sept.8, 1995).