The Kinematic Evolution of Erupting Structures in Confined Solar Flares

TL;DR

This study analyzes the motion of hot blobs in confined solar flares using high-resolution EUV images, revealing their acceleration, deceleration, and timing relative to flare emissions, suggesting similarities with eruptive flares but constrained by stronger magnetic fields.

Contribution

It provides detailed kinematic analysis of hot blobs in confined flares and highlights their eruption dynamics and timing, expanding understanding of flare mechanisms.

Findings

Hot blobs are impulsively accelerated then slow down in confined flares.

Blob velocity peaks precede soft X-ray peaks by minutes.

Erupting blobs can appear before flare onset in some cases.

Abstract

In this Letter, we study the kinematic properties of ascending hot blobs associated with confined flares. Taking advantage of high-cadence extreme-ultraviolet images provided by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory, we find that for the 26 events selected here, the hot blobs are first impulsively accelerated outward, but then quickly slow down to motionlessness. Their velocity evolution is basically synchronous with the temporal variation of the Geostationary Operational Environmental Satellite soft X-ray flux of the associated flares, except that the velocity peak precedes the soft X-ray peak by minutes. Moreover, the duration of the acceleration phase of the erupting blobs is moderately correlated with that of the flare rise phase. For nine of the 26 cases, the erupting blobs even appear minutes prior to the onset of the associated flares. Our results show that a fraction of confined flares also involve the eruption of a magnetic flux rope, which sometimes is formed and heated prior to the flare onset. We suggest that the initiation and development of these confined flares are similar to that of eruptive ones, and the main difference may lie in the background field constraint, which is stronger for the former than for the latter.