Data-constrained Magnetohydrodynamic Simulation of a Long-duration Eruptive Flare

We perform a zero-beta magnetohydrodynamic simulation for the C7.7 class flare initiated at 01:18 UT on 2011 June 21 using the Message Passing Interface Adaptive Mesh Refinement Versatile Advection Code (MPI-AMRVAC). The initial condition for the simulation involves a flux rope, which we realize through the regularized Biot-Savart laws, whose parameters are constrained by observations from the Atmospheric Imaging Assembly (AIA) on the Solar Dynamics Observatory (SDO) and the Extreme Ultraviolet Imager (EUVI) on the twin Solar Terrestrial Relations Observatory (STEREO). This data-constrained initial state is then relaxed to a force-free state by the magnetofrictional module in MPI-AMRVAC. The further time-evolving simulation results reproduce the eruption characteristics obtained by SDO/AIA 94 angstrom, 304 angstrom, and STEREO/EUVI 304 angstrom observations fairly well. The simulated flux rope possesses similar eruption direction, height range, and velocity to the observations. In particular, the two phases of slow evolution and fast eruption are reproduced by varying the density distribution in the light of the draining process of the filament material. Our data-constrained simulations also show other advantages, such as a large field of view (about 0.76 R (circle dot)). We study the twist of the magnetic flux rope and the decay index of the overlying field, and find that in this event, both the magnetic strapping force and the magnetic tension force are sufficiently weaker than the magnetic hoop force, thus allowing the successful eruption of the flux rope. We also find that the anomalous resistivity is necessary to keep the correct morphology of the erupting flux rope.

Automated summary

The study performed a zero-beta magnetohydrodynamic simulation of a C7.7 class flare on June 21, 2011, reproducing eruption characteristics through data-constrained initial conditions. The research highlighted the significance of magnetic field twist and anomalous resistivity in successful eruption of the flux rope.