Evolution Of Quasi-separatrix Layer In Solar Eruptive Events

Quasi-separatrix layer,also called QSL,is a region where magnetic connec-tivity changes drastically and mostly coincides well with the location of flare ribbons in observation.The research about relation between this topological structure and 3-dimensional magnetic reconnection and solar flares is received more and more attention.In this paper,by the theory of QSL we investigated a C5.7 classical two-ribbon solar flare(event 1)which occurred at AR11384 on the 26th December 2011 and a M6.5 solar flare(event 2)which occurred at AR 12371 on the 22nd Jun 2015.Combining the AIA(Atmospheric Imaging Assem-bly)multi-wavelength data and HMI(Heliseismic and Magnetic Imager)vector magnetogrames onboard SDO(Solar Dynamics Observatory),at first we extrap-olated the coronal magnetic field using PF(potential field)model and NLFF-F(nonlinear force free field)model,respectively.In the mean time,we calculate the evolution of the AR magnetic free energy.Then we calculated the slgQ maps of Q factor(magnetic squashing factor)at different height away from solar photosphere with extrapolation result of PF and NLFFF in order to decide the location of Quasi-separatrix layer.Also,we investigate the evolution relation be-tween Quasi-separatrix layer at different height away from solar photosphere and flaring brightening at the same layers.Finally,we studied the multi-wavelength evolution features of the two flares.At the same time,we calculate the observa-tional slipping running speeds in 304A and 335A which are 4.6km/s and 6.3km/s,respectively.We find that the location of QSL that we calculate in chromosphere and corona is in a good agreement with the location of flare ribbons at the same height,and the QSL at different layers has almost the same evolutionary behav-ior in time with flaring brightening of the corresponding layer,which highlights the role of QSL in the research of 3D magnetic reconnection and solar flare,and we suggest that the flare may be triggered by the QSL reconnection.We also suggest that QSL is very important for us to research the connection between 3D magnetic reconnection and 2D magnetic reconnection.