The Role of a Magnetic Topology Skeleton in a Solar Active Region

We investigate the 3D magnetic topology in the active region NOAA 11719 nine hours before and after a flare-coronal mass ejection (CME) event on 2013 April 11. The extrapolated 3D coronal magnetic field is computed employing a boundary integrated model, and a complex magnetic topology skeleton comprising five fairly robust null points and their relevant structures are revealed with a mathematical method based on a Poincaré index of isolated 3D null points. Comparative analyses show that the magnetic topology skeleton in this active region determines geometries of post-flare loops and flare ribbons, and characterizes the initial stage of the CME. The present work demonstrates that the magnetic topology skeleton plays an important role in the process of the flare-CME eruption.