A physical mechanism of flares has emerged from our 2.5-dimensional resistive MHD simulations of the dynamical evolution of current sheet formation and magnetic reconnection and flux rope acceleration subject to the continuous, slow increase of magnetic shear in the arcade. With anomalous nonuniform resistivity in the current sheet the simulation results relate the flux rope's accelerated rising motion with an enhanced magnetic reconnection rate and thus an enhanced reconnection electric field in the current sheet during the flare rise phase. The simulation results provide good quantitative agreement with observations of the acceleration of flux ropes, which are manifested in the form of ejected soft X-ray plasmas, erupting filaments, or CMEs. For the X-class flare events studied in this paper the peak reconnection electric field is ∼ O(103 V m-1) or larger, enough to accelerate electrons to over 100 keV in a field-aligned distance of 0.1 km and produce impulsive hard X-ray emission observed during the flare rise phase.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science