Decipher the Three-Dimensional Magnetic Topology of a Great Solar Flare

Three-dimensional magnetic topology of solar flare plays a crucial role in understanding its explosive release of magnetic energy in the corona. However, such three-dimensional coronal magnetic field is still elusive in direct observation. Here we realistically simulate the magnetic evolution during the eruptive process of a great flare, using a numerical magnetohydrodynamic model constrained by observed solar vector magnetogram. The numerical results reveal that the pre-flare corona contains multi-set twisted magnetic flux, which forms a coherent rope during the eruption. The rising flux rope is wrapped by a quasi-separatrix layer, which intersects itself below the rope, forming a hyperbolic flux tube and magnetic reconnection is triggered there. By tracing the footprint of the newly-reconnected field lines, we reproduce both the spatial location and its temporal evolution of flare ribbons with an expected accuracy in comparison of observed images. This scenario strongly confirms the three-dimensional version of standard flare model.