On the partial eruption of a bifurcated solar filament structure

TL;DR

This study investigates the partial eruption of a bifurcated solar filament, revealing how magnetic reconnection, flux cancellation, and torus instability contribute to the eruption process, supported by multi-instrument observations and magnetic field analysis.

Contribution

It provides new insights into the mechanisms behind partial filament eruptions, highlighting the role of magnetic reconnection and the vertical splitting of filament structures.

Findings

Partial eruption associated with a GOES M1.4 flare.

Magnetic reconnection and flux cancellation trigger the eruption.

Vertical split of filament confirmed by magnetic field analysis.

Abstract

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.