Solar Physics

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

Anisotropy of solar hard X-radiation during flares

  • Gerhard Elwert
  • Eberhard Haug


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.


Anisotropy Flare Angular Distribution Pitch Angle Solar Flare 
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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

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