Evolution of the 3D topology of active region 11158 during 4 days
Jie Zhao  1, 2@  , Hui Li  1@  , Etienne Pariat  3@  , Brigitte Schmieder  3@  , Yang Guo  4, 5@  , Yang Liu  6@  , Thomas Wiegelmann  7@  
1 : Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences  (CAS)
Nanjing 210008 -  China
2 : Graduate School, Chinese Academy of Sciences  (CAS)
Beijing 100864 -  China
3 : Laboratoire d'études spatiales et d'instrumentation en astrophysique  (LESIA)  -  Website
Université Paris VI - Pierre et Marie Curie, Observatoire de Paris, INSU, CNRS : UMR8109, Université Paris VII - Paris Diderot
5, place Jules Janssen 92190 MEUDON -  France
4 : School of Astronomy and Space Science, Nanjing University
Nanjing 210093 -  China
5 : Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education
Nanjing 210093 -  China
6 : W.W. Hansen Experimental Physics Laboratory, Stanford University
Stanford, CA 94305-4085 -  United States
7 : Max-Planck Institute for Solar System Research  (MPS)
K.-Lindau -  Germany

The active region (AR) 11158 has produced several large flares during its lifetime. Based on the high productivity of flares in this AR, we hypothesize that the large-scale magnetic topology has not changed drastically in this period. With the cylindrical equal area (CEA) data from Solar Dynamical Observatory (SDO) / Helioseismic and Magnetic Imager (HMI), we can get the magnetic field in the corona by nonlinear force-free field (NLFFF) extrapolation using Wiegelmann's method. We calculate the squashing degree factor Q in the volume refer to the equation proposed by Pariat & Démoulin (2012). The result does show that there are large-scale quasi-separatrix layers (QSLs) which cross each other during most of the time. We also see some small-scale QSLs related to the X2.2 flare happened on 2011 February 15, which manifest different magnetic connectivity between the flux rope and the arcade around. With SDO/AIA, we confirm that QSLs at the photosphere coincide with flare ribbons, suggesting that energetic particles impact the chromosphere following field lines inside the QSLs.

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