  The partial eruption of a filament channel with bifurcated substructures is
investigated using datasets 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 EUV loops
in close proximity of 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 the vertical split 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 January
28, 2015. The estimated twist number and squashing factor obtained from
nonlinear force free-field extrapolation of the magnetic field data support the
vertical split in filament structure with high twist in upper substructure. The
loss in equilibrium of the upper branch due to torus instability, implying this
as a potential triggering mechanism of the observed partial eruption.
