Z. Huang, M. S. Madjarska, K. Koleva, J. G. Doyle, P. Duchlev, M. Dechev and K. Reardon

Hα spectroscopy and multi-wavelength imaging of a solar flare caused by filament eruption

Fig. 4. Time-Slice image in Hα – 0.8 Å showing the ribbon associated with the surge-like event, the rising filament and its eruption as a dark feature. Bottom: Hα + 0.8 Å slice-time image showing plasma draining in the filament footpoint. The arrows indicate all identified phenomena, i.e., surge-like down-flow (draining of cool material) and the flare’s ribbon. The slice was taken at the location indicated with a white box in Figs. 1 and 2.

Abstract

Context. We study a sequence of eruptive events including filament eruption, a GOES C4.3 flare and a coronal mass ejection.

Aims. We aim to identify the possible trigger(s) and precursor(s) of the filament destabilisation; investigate flare kernel characteristics; flare ribbons/kernels formation and evolution; study the interrelation of the filament-eruption/flare/coronal-mass- ejection phenomena as part of the integral active-region magnetic field configuration; determine Hα line profile evolution during the eruptive phenomena.

Methods. Multi-instrument observations are analysed including Hα line profiles, speckle images at Hα – 0.8 Å and Hα + 0.8 Å from IBIS at DST/NSO, EUV images and magnetograms from the SDO, coronagraph images from STEREO and the X-ray flux observations from FERMI and GOES.

Results. We establish that the filament destabilisation and eruption are the main trigger for the flaring activity. A surge-like event with a circular ribbon in one of the filament footpoints is determined as the possible trigger of the filament destabilisation. Plasma draining in this footpoint is identified as the precursor for the filament eruption. A magnetic flux emergence prior to the filament destabilisation followed by a high rate of flux cancelation of 1.34 × 1016 Mxs−1 is found during the flare activity. The flare X-ray lightcurves reveal three phases that are found to be associated with three different ribbons occurring consecutively. A kernel from each ribbon is selected and analysed. The kernel lightcurves and Hα line profiles reveal that the emission increase in the line centre is stronger than that in the line wings. A delay of around 5–6 mins is found between the increase in the line centre and the occurrence of red asymmetry. Only red asymmetry is observed in the ribbons during the impulsive phases. Blue asymmetry is only associated with the dynamic filament.

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Last Revised: 2014 May 6th