Advertisement

Solar Physics

, Volume 20, Issue 2, pp 413–421 | Cite as

Anisotropy of solar hard X-radiation during flares

  • Gerhard Elwert
  • Eberhard Haug
Article

Abstract

The angular distribution of solar flare associated hard X-rays (≳ 10 keV) is calculated on the assumption that they originate as bremsstrahlung emission of energetic electrons with a power law spectrum. For the cross section the relativistic Sauter formula was used. Supposing the electrons to move in a fixed direction, the X-radiation is considerably anisotropic, especially at high photon energies. Taking into account a magnetic field, the anisotropy decreases with increasing pitch angles of the electrons. The anisotropic angular distribution of solar X-radiation seems to be connected with the centre-to-limb variation of hard X-ray bursts and with the correlation of shortwave fadeouts and geomagnetic crochets to Hα flares.

Keywords

Anisotropy Flare Angular Distribution Pitch Angle Solar Flare 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Cline, T. L. and McDonald, F. B.: 1968, Solar Phys. 5, 507.Google Scholar
  2. Cline, T. L., Holt, S. S., and Hones, E. W. Jr.: 1968, J. Geophys. Res. 73, 434.Google Scholar
  3. Dodson, H. W. and Hedeman, E. R.: 1958, Astrophys. J. 128, 636.Google Scholar
  4. Drake, J. F.: 1971, Solar Phys. 16, 152.Google Scholar
  5. Elwert, G.: 1939, Ann. Phys. 34, 178.Google Scholar
  6. Elwert, G. and Haug, E.: 1970, Solar Phys. 15, 234.Google Scholar
  7. Holt, S. S. and Ramaty, R.: 1969, Solar Phys. 8, 119.Google Scholar
  8. Kane, S. R. and Anderson, K. A.: 1970, Astrophys. J. 162, 1003.Google Scholar
  9. Lin, R. P.: 1970, Solar Phys. 12, 266.Google Scholar
  10. Ohki, K.-I.: 1969, Solar Phys. 7, 260.Google Scholar
  11. Pinter, S.: 1969, Solar Phys. 8, 142.Google Scholar
  12. Sauter, F.: 1934, Ann. Physik 20, 404.Google Scholar
  13. Stranz, D.: 1950, A.E.Ü. 4, 217.Google Scholar
  14. Takakura, T. and Kai, K.: 1966, Publ. Astron. Soc. Japan 18, 57.Google Scholar
  15. Takao, K. and Nakadan, Y.: 1970, Space Research X, 936.Google Scholar
  16. Tindo, P. I., Ivanov, V. D., Mandel'stam, S. L., and Shuryghin, A. I.: 1970, Solar Phys. 14, 204.Google Scholar

Copyright information

© D. Reidel Publishing Company 1971

Authors and Affiliations

  • Gerhard Elwert
    • 1
  • Eberhard Haug
    • 1
  1. 1.Lehrstuhl für Theoretische Astrophysik der Universität TübingenWest Germany

Personalised recommendations