Data-constrained MHD Simulation of a Multi-ribbon Flare Corresponding to a Successful and a Confined Eruption

Abstract The formation and eruption mechanisms of multi-ribbon flares are extremely complicated, especially when the flare is associated with homologous eruptions in same region. In this paper, we investigate such an event, corresponding to a successful confined eruption. This M7.1 flare, starting at 12:33 UT on 2011 September 24 active region NOAA 11302. We obtain coronal magnetic configuration for region, using nonlinear force-free field extrapolation based photospheric magnetogram 12:00 UT. Taking as initial condition, perform data-constrained MHD simulation study evolution topology analyze null points 3D squashing degree indicating existence three flux ropes two spine–fan structures. model reproduces rising processes ropes, which form consistent observations shown 94 Å: large-scale that followed by small-scale By analyzing configuration, Lorentz force, decay index, find torus instability plays important role driving large rope. reconnection above medium rope changes direction overlying field, provides downward component force confine