The Causes of Peripheral Coronal Loop Contraction and Disappearance Revealed in a Magnetohydrodynamic Simulation of Solar Eruption

TL;DR

This study uses a magnetohydrodynamic simulation to investigate the physical mechanisms behind peripheral coronal loop contraction and disappearance during solar eruptions, supporting the implosion conjecture and revealing their dynamic interactions.

Contribution

It provides the first detailed simulation-based explanation for the causes of peripheral loop contraction and disappearance, linking magnetic energy dynamics to observable phenomena.

Findings

Loop contraction correlates with magnetic energy changes in the core.

Magnetic pressure reduction causes loop shrinkage, supporting the implosion conjecture.

Loop disappearance results from reconnection with erupting structures.

Abstract

The phenomenon of peripheral coronal loop contraction during solar flares and eruptions, recently discovered in observations, gradually intrigues solar physicists. However, its underlying physical mechanism is still uncertain. One is Hudson (2000)'s implosion conjecture which attributes it to magnetic pressure reduction in the magnetic energy liberation core, while other researchers proposed alternative explanations. In previous observational studies we also note the disappearance of peripheral shrinking loops in the late phase, of which there is a lack of investigation and interpretation. In this paper, we exploit a full MHD simulation of solar eruption to study the causes of the two phenomena. It is found that the loop motion in the periphery is well correlated with magnetic energy accumulation and dissipation in the core, and the loop shrinkage is caused by a more significant reduction in magnetic pressure gradient force than in magnetic tension force, consistent with the implosion conjecture. The peripheral contracting loops in the late phase act as inflow to reconnect with central erupting structures, which destroys their identities and naturally explains their disappearance. We also propose a positive feedback between the peripheral magnetic reconnection and the central eruption.