At 17:48 UT on the 29th of March 2014, NOAA active region (AR) 12017 produced an X1 flare observed simultaneously by an unprecedented number of observatories. Among these were the Interface Region Imaging Spectrometer (IRIS) and Hinode’s Extreme Ultraviolet Imaging Spectrometer (EIS), joint observations from which provide an excellent opportunity to investigate the dynamics of the solar atmosphere for the period leading up to the X-flare.
This work presents the results of the study of two areas of the AR: Region A, the site of a C-class flare observed over an hour prior to the X-flare, and Region B, an area of the filament which shows intriguing non-thermal velocities and Doppler blue shifts roughly 40 minutes prior to the X-flare.
The strongly blue shifted plasma in Region B is observed approximately simultaneously in the Chromosphere, Transition region and the Corona. Once triggered, region B continued to show dynamics in the time leading up to the X-flare. This rise of the filament combined with the preceding C-class flare is suggested to cause the destabilisation of the magnetic fields in the AR leading to the X-flare and subsequent filament eruption.
We shall also discuss these results in relation to models of the evolution of the non-potential magnetic field present in this active region.