Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-Class Solar Flare

TL;DR

This study analyzes the 2014 September 10 X-class solar flare, revealing that slipping magnetic reconnection, flux rope eruption, and chromospheric evaporation are key processes, with precursor signatures indicating early flare activity consistent with 3D standard models.

Contribution

It demonstrates that energy release in the flare occurs via slipping reconnection rather than coronal implosion, providing detailed observational evidence of this process in a major solar flare.

Findings

Slipping reconnection occurs throughout the flare with velocities of 20-40 km/s.

Flux rope existed and erupted before coronal implosion, indicating a different energy release mechanism.

Precursor signatures include EUV brightenings and non-thermal X-ray emissions, linked to slipping reconnection.

Abstract

We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. The slipping reconnection is found to be present throughout the flare from its early phase. Flare loops are seen to slip in opposite directions towards both ends of the ribbons. Velocities of 20--40 km\,s$^{-1}$ are found within time windows where the slipping is well resolved. The warm coronal loops exhibit expanding and contracting motions that are interpreted as displacements due to the growing flux rope that subsequently erupts. This flux rope existed and erupted before the onset of apparent coronal implosion. This indicates that the energy release proceeds by slipping reconnection and not via coronal implosion. The slipping reconnection leads to changes in the geometry of the observed structures at the \textit{IRIS} slit position, from flare loop top to the footpoints in the ribbons. This results in variations of the observed velocities of chromospheric evaporation in the early flare phase. Finally, it is found that the precursor signatures including localized EUV brightenings as well as non-thermal X-ray emission are signatures of the flare itself, progressing from the early phase towards the impulsive phase, with the tether-cutting being provided by the slipping reconnection. The dynamics of both the flare and outlying coronal loops is found to be consistent with the predictions of the standard solar flare model in 3D.