Gottfried Mann

9th RHESSI Workshop

Genova, Italy, September 1-5 2009

Participants

Gottfried Mann

Astrophysical Institute Potsdam, Germany

Email: GMann (at) aip.de

Group 2

Contribution: Among other things, solar flares are accompanied with the production of a huge number of energetic electrons as seen in the nonthermal radio and X-ray radiation of the Sun. Observations of the RHESSI satellite show that 10^36 electrons with energies > 20 keV are typically produced per second during large flares. They are related to a power of about 10^22 W. These electrons play an important role, since they carry a substantial part of the energy released during a flare. The flare is regarded within the framework of the magnetic reconnection scenario. Under which conditions so much electrons are accelerated up to high energies during a fraction of a second is a still open question. The region, in which the electrons are accelerated up to high energies are considered as a black box. The conditions in the acceleration region in the corona are deduced by using the conservation of the total electron number and energy. In the acceleration region, there are typical electron number densities of about 2.65 x 10^9 cm^-3 and magnetic fields of about 100 G. That are regions with large Alfvén speeds of about 4240 km/s. Then, sufficiently enough energetic electrons (as required by the RHESSI observations) are only generated if the plasma inflow towards the reconnection site has an Alfvén-Mach number of about 0.7. That leads to an outflow with a speed of about 8900~km s^-1.

Group 4

Contribution: -

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