Magnetic Field Configuration Associated With A Slow Rise Eruptive X1.2 Flare In Active Region 11944

Using multi-wavelength observations, we studied a gradual X1.2 flare that erupted on January 7, 2014, in active region (AR) NOAA 11944 located near the disk center. A fast coronal mass ejection (CME) was observed following the flare; however, it was strongly deflected in the south-west direction. We used SDO/HMI data to perform extrapolation of coronal magnetic fields and to study the evolution of AR magnetic fields before the eruption. Extrapolated data allowed us to detect a flux rope (FR) present at the eruption site several hours before the event. That was the only well-defined FR present in the AR. Although the strapping and core fields in the model have significantly changed after the flare, the model FR did not erupt. We note that a chromospheric filament was observed at the eruption site prior to and after the flare. The eruption site was located under sunspot canopy fields with a decay index of about 0.5, which is not favorable for torus instability to develop. That might have caused the erupting fields to slide along the canopy rather than vertically erupt, thus explaining the slow rise of the flare as well as the observed direction of the resulting CME. We employed sign-singularity tools to quantify the evolutionary changes in a model twist and observed current helicity data, and found rapid enhancements in the current systems in both data sets prior to the event as well as their rapid exhaustion after the event onset.