Unveiling the Initiation Route of Coronal Mass Ejections through their Slow Rise Phase

TL;DR

This study uses advanced simulations to reveal a detailed, multi-mechanism initiation route for coronal mass ejections, highlighting the complex interplay of magnetic reconnection and instabilities in their early evolution.

Contribution

It provides a comprehensive, sequential model of CME initiation involving multiple coupled physical mechanisms, advancing understanding beyond single-mechanism explanations.

Findings

CME slow rise is triggered by hyperbolic flux tube reconnection.

Coupling of reconnection and torus instability drives the slow rise.

Impulsive acceleration begins with fast magnetic reconnection and torus instability.

Abstract

Understanding the early evolution of coronal mass ejections (CMEs), in particular their initiation, is the key to forecasting solar eruptions and induced disastrous space weather. Although many initiation mechanisms have been proposed, a full understanding of CME initiation, which is identified as a slow rise of CME progenitors in kinematics before the impulsive acceleration, remains elusive. Here, with a state-of-the-art thermal-magnetohydrodynamics simulation, we determine a complete CME initiation route in which multiple mainstream mechanisms occur in sequence yet are tightly coupled. The slow rise is first triggered and driven by the developing hyperbolic flux tube (HFT) reconnection. Subsequently, the slow rise continues as driven by the coupling of the HFT reconnection and the early development of torus instability. The end of the slow rise, i.e., the onset of the impulsive acceleration, is induced by the start of the fast magnetic reconnection coupled with the torus instability. These results unveil that the CME initiation is a complicated process involving multiple physical mechanisms, thus being hardly resolved by a single initiation mechanism.