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Stephane Regnier Submitted: 20070907 08:41
To understand the physics of solar flares, including the local reorganisation of the magnetic field and the acceleration of energetic particles, we have first to estimate the free magnetic energy available for such phenomena, which can be converted into kinetic and thermal energy. The free magnetic energy is the excess energy of a magnetic configuration compared to the minimumenergy state, which is a linear forcefree field if the magnetic helicity of the configuration is conserved. We investigate the values of the free magnetic energy estimated from either the excess energy in extrapolated fields or the magnetic virial theorem. For four different active regions, we have reconstructed the nonlinear forcefree field and the linear forcefree field corresponding to the minimumenergy state. The free magnetic energies are then computed. From the energy budget and the observed magnetic activity in the active region, we conclude that the free energy above the minimumenergy state gives a better estimate and more insights into the flare process than the free energy above the potential field state.
Authors: S. Regnier and E. R. Priest
Projects: None

Publication Status: Accepted ApJ Letters
Last Modified: 20070907 10:19


