Re-flaring of a Post-Flare Loop System Driven by Flux Rope Emergence and Twisting

TL;DR

This study investigates the rapid re-flaring of post-flare loops driven by flux rope emergence and twisting, revealing the magnetic evolution leading to a second CME/flare within 16 hours.

Contribution

It demonstrates how flux rope emergence and twisting can cause re-flaring of post-flare loops, providing new insights into magnetic evolution and flare prediction.

Findings

Flux rope kept rising with increasing twist and length.

Post-flare loops re-flared within approximately 16 hours.

Magnetic flux emergence and sunspot rotation drove the re-flaring.

Abstract

In this letter, we study in detail the evolution of the post-flare loops on 2005 January 15 that occurred between two consecutive solar eruption events, both of which generated a fast halo CME and a major flare. The post-flare loop system, formed after the first CME/flare eruption, evolved rapidly, as manifested by the unusual accelerating rise motion of the loops. Through nonlinear force-free field (NLFFF) models, we obtain the magnetic structure over the active region. It clearly shows that the flux rope below the loops also kept rising accompanied with increasing twist and length. Finally, the post-flare magnetic configuration evolved to a state that resulted in the second CME/flare eruption. This is an event in which the post-flare loops can re-flare in a short period of $\sim$16 hr following the first CME/flare eruption. The observed re-flaring at the same location is likely driven by the rapid evolution of the flux rope caused by the magnetic flux emergence and the rotation of the sunspot. This observation provides valuable information on CME/flare models and their prediction.