A Hot Cusp-Shaped Confined Solar Flare

TL;DR

This study reports the observation of a static hot cusp in a confined solar flare, highlighting differences from eruptive flares and suggesting prolonged heating due to slow reconnection and plasma upflows.

Contribution

It provides new insights into the formation and evolution of hot cusp structures in confined flares, contrasting with standard eruptive flare models.

Findings

Observed a static hot cusp during a confined flare.

Identified prolonged hot emission during decay phase.

Linked cusp formation to kinked magnetic arcade and slow reconnection.

Abstract

We analyze a confined flare that developed a hot cusp-like structure high in the corona (H ~ 66 Mm). A growing cusp-shaped flare arcade is a typical feature in the standard model of eruptive flares, caused by magnetic reconnection at progressively larger coronal heights. In contrast, we observe a static hot cusp during a confined flare. Despite an initial vertical temperature distribution similar to that in eruptive flares, we observe a distinctly different evolution during the late (decay) phase, in the form of prolonged hot emission. The distinct cusp shape, rooted at locations of non-thermal precursor activity, was likely caused by a magnetic field arcade that kinked near the top. Our observations indicate that the prolonged heating was a result of slow local reconnection and an increased thermal pressure near the kinked apexes due to continuous plasma upflows.