fl235.yoshimori11 Posted: 26-Apr-96 Updated: 27-Jan-97 Events specified: Flares of 27-Oct-91 05:40 UT and of 3-Dec-91 16:36 UT
M.Yoshimori(yosimori@rikkyo.ac.jp), K.Morimoto, K.Suga, T.Matsuda and N.Saita
Abstract: Two gamma-ray flares were observed with a gamma-ray spectrometer and two X-ray imagers (HXT and SXT) aboard Yohkoh. The gamma-ray flare on 27 October 1991 showed strong narrow deexcitation lines and two bright hard X-ray sources. We discuss a gamma-ray production site from comparison of the gamma-ray (4.5 - 6.8 MeV) time profile with the hard X-ray (53 - 93 keV) time profile of each hard X-ray source. The gamma-ray lines are thought to be produced at one of the two hard X-ray sources. The gamma-ray flare on 3 December 1991 showed strong continuum extending to 8 MeV without detectable gamma-ray lines. It implies that electrons were preferentially accelerated to relativistic energies. The rapid enhancement in hard X-ray (53 - 93 keV) emission was observed simultaneously with the large change in flaring loop structures. It suggests that the electrons were efficiently accelerated by strong electric field induced by the rapid variation in the magnetic field.
This paper was submitted to AIP (American Institute Physics) Proceedings of Workshop on High Energy Solar Physics (eds. R.Ramaty, N.Mandzhavidze and H.X.Hua).
Required observations: WBS, HXT and SXT
Update 27-Jan-97
We have reached the goal of the proposal of fl235:
M.Yoshimori, K.Morimoto, K.Suga, T.Matsuda and N.Saita
This paper was published in AIP Conference Proceedings No.235 : High Energy Solar Physics, eds. R.Ramaty, N.Mandzhavidze and X,M.Hua, p.208.
Abstract:
Two gamma-ray flares were observed with a gamma-ray spectrometer and two X-ray imagers aboard Yohkoh. The gamma-ray flare on 27 October 1991 showed strong narrow deexcitation lines and two bright hard X-ray sources. We discuss a gamma-ray production site from comparison of the gamma-ray (4.5 - 6.8 MeV) time profile with the hard X-ray (53 - 93 keV) time profile of each hard X-ray bright source. The gamma-ray lines are thought to be produced at one of the two hard X-ray sources. The gamma-ray flare on 3 December 1991 showed a strong continuum extending to about 8 MeV without detectable gamma-ray line. It implies that electrons were preferentially accelerated to relativistic energies. The rapid enhancement in hard X-rays (53 - 93 keV) emission was observed nearly simultaneously with the large change in flaring loop structures. It suggests that the electrons were efficiently accelerated by strong electric field induced by the rapid variation in the magnetic field.