Data-constrained MHD Simulation for the Eruption of a Filament–Sigmoid System in Solar Active Region 11520

The separation of a filament and sigmoid is observed during an X1.4 flare on July 12, 2012 in solar active region 11520, but the corresponding magnetic field change not clear. We construct data-constrained magnetohydrodynamic simulation filament-sigmoid system with flux rope insertion method eruption code, which produces evolution that may explain low-lying high-lying hot channel (sigmoid). initial state model contains hyperbolic tube, null point structure overlying confining fields. find reconnections at make right footpoint move from one positive polarity (P1) to another (P3). tether-cutting reconnection tube occurs quickly cuts off connection sigmoid. In end, erupts grows into coronal mass ejection, while stays stable. double J-shaped ribbons, semi-circular ribbon, brightenings several loops are reproduced simulation, where includes impulsive acceleration propagation phases.