Sympathetic Solar Filament Eruptions on 2015 March 15

TL;DR

This study examines the mechanisms behind sympathetic filament eruptions during the 2015 March 15 solar event, highlighting the role of magnetic fields and small-scale motions in triggering and influencing eruption outcomes.

Contribution

It provides detailed analysis of the magnetic conditions and triggers involved in sympathetic filament eruptions, using multi-wavelength observations and magnetic field extrapolation methods.

Findings

Small-scale filament motion can trigger eruptions.

Open magnetic field regions facilitate filament acceleration.

Magnetic confinement influences eruption success or failure.

Abstract

The 2015 March 15 coronal mass ejection as one of the two that together drove the largest geomagnetic storm of solar cycle 24 so far was associated with sympathetic filament eruptions. We investigate the relations between the different filaments involved in the eruption. A surge-like small-scale filament motion is confirmed as the trigger that initiated the erupting filament with multi-wavelength observations and using a forced magnetic field extrapolation method. When the erupting filament moved to an open magnetic field region, it experienced an obvious acceleration process and was accompanied by a C-class flare and the rise of another larger filament that eventually failed to erupt. We measure the decay index of the background magnetic field, which presents a critical height of 118 Mm. Combining with a potential field source surface extrapolation method, we analyze the distributions of the large-scale magnetic field, which indicates that the open magnetic field region may provide a favorable condition for F2 rapid acceleration and have some relation with the largest solar storm. The comparison between the successful and failed filament eruptions suggests that the confining magnetic field plays an important role in the preconditions for an eruption.