Hostname: page-component-586b7cd67f-2brh9 Total loading time: 0 Render date: 2024-11-30T06:36:07.248Z Has data issue: false hasContentIssue false
  • English
  • Français

Gamma-Ray Spectral Observations with Yohkoh

Published online by Cambridge University Press:  12 April 2016

M. Yoshimori ,
K. Suga ,
K. Morimoto ,
T. Hiraoka ,
J. Sato ,
K. Kawabata  and
K. Ohki
M. Yoshimori
Affiliation:
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171, Japan
K. Suga
Affiliation:
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171, Japan
K. Morimoto
Affiliation:
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171, Japan
T. Hiraoka
Affiliation:
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171, Japan
J. Sato
Affiliation:
Department of Physics, Rikkyo University, Toshima-ku, Tokyo 171, Japan
K. Kawabata
Affiliation:
Department of Physics and Astrophysics, Nagoya University, Nagoya 464-01, Japan
K. Ohki
Affiliation:
National Astronomical Observatory, Mitaka, Tokyo 181, Japan

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

We present gamma-ray observations of the 1991 October 27, November 15, and December 3 flares with the Yohkoh gamma-ray and hard X-ray spectrometers. The October 27 flare (X6.1 /3B) shows significant gamma-ray line emission, and the temporal evolution of the gamma-ray line-to-bremsstrahlung flux ratio indicates that protons and electrons were complicatedly accelerated during flare. The December 3 flare (X2.0/2B) shows a strong bremsstrahlung continuum extending to 10 MeV and indicates that electrons were preferentially accelerated to 10 MeV. A line feature at 420 keV was observed from the November 15 flare (X1.0/3B). This is most likely due to a compound of redshifted nuclear deexcitation lines of Be (429 keV) and Li (478 keV) resulting from He-He reactions. The spectral feature indicates that the accelerated He nuclei suffer strong pitch-angle scattering in the corona and form a downward-peaked distribution. Furthermore, the November 15 flare exhibits evidence of positron annihilation line at 511 keV. The positron production processes and the electron density of the annihilation region are discussed on the basis of the temporal characteristics of 511 keV line emission.

Subject headings: line: identification — Sun: flares — Sun: X-rays, gamma-rays

Type
Solar Flares
Information
International Astronomical Union Colloquium , Volume 142: Particle Acceleration Phenomena in Astrophysical Plasmas , 1994 , pp. 639 - 643
Copyright
Copyright © The American Astronomical Society 1994

References

Chupp, E.L. 1987, Phys. Scripta, T18, 5 Google Scholar
Feldman, U. 1992, preprintGoogle Scholar
Forrest, D.J. 1983, in Positron-Electron Pairs in Astrophysics, ed. Burns, M. L., Harding, A.K., & Ramaty, R. (New York: AIP), 3 Google Scholar
Hiei, E., Nakagomi, Y., & Takuma, H. 1992, PASJ, L77 Google Scholar
Hua, X.M., & Lingenfelter, R.E. 1987, Sol. Phys., 107, 351 CrossRefGoogle Scholar
Kozlovsky, B., & Ramaty, R. 1974, ApJ, 191, L43 CrossRefGoogle Scholar
Kozlovsky, B., & Ramaty, R. 1977, Ap. Letters, 19, 19 Google Scholar
Murphy, R.J., Hua, X.M., Kozlovsky, B., & Ramaty, R. 1990, ApJ, 351, 299 Google Scholar
Murphy, R.J., Kozlovsky, B., & Ramaty, R. 1988, ApJ, 331, 1029 Google Scholar
Murphy, R.J., & Ramaty, R. 1984, Adv. Space Res., 4, No. 7, 127 CrossRefGoogle Scholar
Ramaty, R. 1979, in Particle Acceleration Mechanisms in Astrophysics, ed. Arons, J., Max, C., & Mckee, C. (New York: AIP) 135 Google Scholar
Ramaty, R., Mandzhavidze, N., Kozlovsky, B., & Skibo, J. 1993, Adv. Space Res., 13, 275 Google Scholar
Rieger, E. 1989, Sol. Phys., 121, 323 Google Scholar
Rieger, E., & Marschhäuser, H. 1990, in Proc. Max ‘91 Workshop No. 3, Max ‘91 /SMM Solar Flares, ed. Winglee, R.M. & Kiplinger, A.L. (Boulder: Univ. of Colorado), 68 Google Scholar
Share, G.H., Chupp, E.L., Forrest, D.J., & Rieger, E. 1983, in Positron-Electron Pairs in Astrophysics, ed. Bums, M.L., Harding, A.K., & Ramaty, R. (New York: AIP), 15 Google Scholar
Yoshimori, M. 1989, Space Sci. Rev., 51, 85 CrossRefGoogle Scholar
Yoshimori, M., et al. 1991, Sol. Phys. 136, 69 CrossRefGoogle Scholar
Yoshimori, M., Takai, Y., Morimoto, K., Suga, K., & Ohki, K. 1992a, PASJ, 44, L107 Google Scholar
Yoshimori, M., et al. 1992b, PASJ, 44, L51 Google Scholar
Yoshimori, M., & Watanabe, H. 1985, J. Phys. Soc. Japan, 54, 2100 CrossRefGoogle Scholar