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The partial eruption of a filament channel with bifurcated substructures is investigated using data sets obtained from both ground-based and space-borne facilities. Small-scale flux reconnection/cancellation events in the region triggered the pile-up of ambient magnetic field, observed as bright extreme ultraviolet (EUV) loops in close proximity to the filament channel. This led to the formation of a V-shaped cusp structure at the site of interaction between the coalesced EUV loops and the filament channel, with the presence of distinct plasmoid structures and associated bidirectional flows. Analysis of imaging data from SDO /AIA further suggests vertical splitting of the filament structure into two substructures. The perturbed upper branch of the filament structure rose up and erupted with the onset of an energetic GOES M1.4 flare at 04:30 ut on 2015 January 28. The estimated twist number and squashing factor obtained from non-linear force free-field extrapolation of the magnetic field data support the vertical split in the filament structure with high twist in the upper substructure. The loss in equilibrium of the upper branch due to torus instability implies that this is a potential triggering mechanism for the observed partial eruption. [ABSTRACT FROM AUTHOR]

The active region NOAA (National Oceanic and Atmospheric Administration) AR 10486 which appeared on the solar disc in 2003 October produced a lot of space weather related activity. Here, we report on the co-spatial evolution of the photospheric Doppler enhancements and the chromospheric Hα flare ribbons observed during the 4B/X17.2 class solar flare of 2003 October 28 in this active region. These velocity enhancements exactly match the Hα brightness enhancements in space, and are delayed by approximately 1 min in time. Hα brightness attains a maximum nearly at the same time as the peak seen in light curves in high-energy emission observed by KORONAS ( Kuznetsov et al. 2006 ). [ABSTRACT FROM AUTHOR]