Observations and Modeling of Solar Eruptions

Observations and Modeling of Solar Eruptions
Yingna Su1
Purple Mountain Observatory, Chinese Academy of Sciences, China
In this talk, I will apply the flux rope insertion method (van Ballegooijen 2004) to construct
magnetic field models for several regions with solar eruptions. Interesting findings include but not
limited to: The axial flux of the flux rope is very well constrained by observations, while poloidal flux
has a much larger range; The studied active region filaments can be modeled with highly sheared and
weakly twisted flux ropes; The onset of the eruption is better understood with the aid of the 3D
magnetic field models; This method is quite flexible and provides information about the stability of
the resulting fields. The studies show that an eruptive flare occurs when the axial flux in the pre-flare
magnetic fields is close to the threshold of instability, otherwise a confined flare will occur. By
increasing the axial flux of the inserted flux rope, one can construct an unstable model, which displays
a magnetic reconnection topology with X-point. The reconnected field lines closely match the
observed features at the early stage of the eruption. The unstable models can be used as initial
conditions to realistic 3D magnetohydrodynamic (MHD) simulations to study the evolution and
propagation of eruptions.