Greifswald 2009 – scientific programme

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EP: Fachverband Extraterrestrische Physik

EP 9: Sun III and Heliophysics I

EP 9.8: Talk

Wednesday, April 1, 2009, 15:45–16:00, Zahnklinik

Budget of energetic electrons during solar flares — •Gottfried Mann — Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D-14482 Potsdam

Solar flares are basically defined as a strong enhancement of the emission of electromagnetic waves, from the radio up to the γ-ray range. They are accompanied with the production of a large number of energetic electrons as seen in the nonthermal radio and X-ray radiation. Observations of the RHESSI satellite show that 10³⁶ electrons with energies > 20 keV are typically produced per second during large flares. They are related with a power of about 10²² W. These electrons carry a substantial part of the energy released during a flare. The flare is regarded within the framework of the magnetic reconnection scenario. In which way so much electrons are accelerated up to high energies during a fraction of a second is a still open question. The region of acceleration is considered a a black box. The conditions in the acceleration region are deduced by using the conservation of the total electron number and energy. In result, the acceleration takes place in regions of large Alfvén speeds of about 4300 km/s.