Study of a flare and associated surge on solar active region NOAA 11476

M. LÓPEZ FUENTES; C. H. MANDRINI; C. BUSTOS; M. POISSON

Ciudad de Buenos Aires

Conferencia; 11th Latin American Conference on Space Geophysics; 2018

Asociación Latinoamericana de Geofísica Espacial

We analyze an M4.1 flare and associated surge that occurred in active region (AR) NOAA 11476 on 9 May 2012, 21:01 UT. The flare took place at the same location and approximately 9 hr after the onset of a first more intense (M4.7) event that we studied in a previous work. The AR configuration is extended and mostly bipolar although with some degree of complexity. The site of both flares coincides with an emerging minor bipole (as observed in SDO/HMI line of sight magnetograms) located in between the two main AR polarities. This bipole is observed to rotate by around 150 deg during approximately 36 hs before the occurrence of the events, indicating a strong injection of twist into the overlying coronal magnetic structure. A preliminary study of the evolution of the event, using different EUV bands of the SDO/AIA instrument, suggests a classical quadrupolar configuration with the possible presence of a null point above the emerging twisted bipole. The succession and location of the flare brightenings and the surge ejection allows us to determine the approximate location of the site where the pre-existing structures interact, via magnetic reconnection, with the newly emerging bipole. We will complement our analysis of the event with X-ray data from the Hinode/XRT telescope and linear force-free extrapolations of the coronal magnetic structure, using as boundary conditions line of sight photospheric magnetograms obtained with SDO/HMI. We will analyze the magnetic model, identifying the presence and location of quasi-separatrix layers (QSLs), to interpret the role of the different interacting structures in the triggering and evolution of the event.