The Non-Eruptive Reconfiguration of a Quiescent Filament After a Nearby Active Region Emergence

TL;DR

This study investigates why a quiescent solar filament remained stable despite nearby active region emergence, highlighting the role of magnetic reconnection and flux orientation in preventing eruptions.

Contribution

It provides observational evidence that ongoing magnetic reconnection and flux orientation influence filament stability during active region emergence.

Findings

Persistent slow reconnection stabilizes the filament.

Flux orientation relative to ambient field is critical.

Reconnection can relieve magnetic stress, preventing eruptions.

Abstract

The unpredictability of solar filament eruptions presents major challenges for forecasting space weather, as such eruptions frequently drive coronal mass ejections (CMEs) that impact the heliosphere. While nearby flux emergence is often linked to their destabilisation, the specific characteristics of both the emerging flux and the filament that determine whether an eruption occurs remain unclear. We report observations of a quiescent filament that did not erupt following the nearby emergence of active region NOAA 13270 and a subsequent C-class flare in April 2023. Our analysis combines multi-viewpoint extreme ultraviolet (EUV) imaging and X-ray imaging with EUV spectroscopy, radio imaging and measurements of, and extrapolations from, the photospheric magnetic field. We identify the formation of a coronal null point and fan-spine topology at the interface between the active region and filament which exhibited persistent slow reconnection, indicated by chromospheric brightenings, persistent radio emission, and plasma upflows. Our results indicate that ongoing reconnection and jets can relieve magnetic stress and enable filament stability, even when under strong perturbation. We suggest that the orientation of emerging flux relative to the ambient field is a critical parameter in filament evolution, and provide observational constraints for models of filament stability and eruption.