Multi-point study of the energy release and impulsive CME dynamics in an eruptive C7 flare

TL;DR

This study combines multi-view observations to analyze the energy release, plasma dynamics, and CME evolution during a long-duration eruptive C7 flare, revealing phases of impulsive acceleration and independent evolution of flare and CME.

Contribution

It provides a detailed multi-point analysis of the flare and CME dynamics, highlighting the temporal relationship and independence between flare energy release and CME acceleration.

Findings

CME acceleration correlates with initial hot plasma emission and magnetic reconnection.

Post-acceleration HXR bursts show spectral hardening without further CME acceleration.

The flare and CME evolve independently after the first 25 minutes.

Abstract

We combine observations from different vantage points to perform a detailed study of a long duration eruptive C7 class flare that occurred on 17 April 2021 and was partially occulted from Earth view. The dynamics and thermal properties of the flare-related plasma flows, the flaring arcade, and the energy releases and particle acceleration are studied together with the kinematic evolution of the associated CME in order to place this long duration event in context of previous eruptive flare studies. The flare showed hard X-ray (HXR) bursts over the duration of an hour in two phases lasting from 16:04 UT to 17:05 UT. During the first phase, a strong increase in emission from hot plasma and impulsive acceleration of the CME was observed. The CME acceleration profile shows a three-part evolution of slow rise, acceleration, and propagation in line with the first STIX HXR burst phase, which is triggered by a rising hot (14 MK) plasmoid. During the CME acceleration phase, we find signatures of ongoing magnetic reconnection behind the erupting structure, in agreement with the standard eruptive flare scenario. The subsequent HXR bursts that occur about 30 minutes after the primary CME acceleration show a spectral hardening (from $\delta \approx $ 7 to $\delta \approx $ 4) but do not correspond to further CME acceleration and chromospheric evaporation. Therefore, the CME-flare feedback relationship may only be of significance within the first 25 minutes of the event under study, as thereafter the flare and the CME eruption evolve independently of each other.