Dynamics, thermodynamics, and fine structure of virtual erupting filaments

¹ Centre for mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Leuven, Belgium
² School of Astronomy and Space Science and Key Laboratory of Modern Astronomy and Astrophysics, Nanjing University, Nanjing, PR China
³ Universidad de Mendoza, Mendoza, Argentina

^⋆ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 2 November 2025
Accepted: 6 February 2026

Abstract

Context. It is not fully understood why some solar filaments erupt, whereas others do not. Filaments that erupt typically undergo a slow rise, followed by an acceleration phase; this transition requires further investigation. Erupting prominences have been observed to heat up during the acceleration phase, but the origin of this heating remains unclear. Moreover, some coronal mass ejections possess additional fine structure in white-light observations, in addition to the general three-structure morphology.

Aims. Our objective is to elaborate on the dynamics of erupting prominences, investigate why erupting filaments heat up in the acceleration phase, and correlate our findings with observations.

Methods. We used the open-source software tool MPI-AMRVAC to solve the 2.5D magnetohydrodynamic (MHD) equations on a coronal domain extending up to 300 Mm, using adaptive mesh refinement to achieve high resolution. We used controlled combinations of footpoint shearing and converging motions on an initial magnetic arcade to obtain erupting flux ropes, where self-consistent prominence and coronal rain formation occur due to thermal instability. We find both non-erupting and erupting cases, related to the energization of the system. We compared our erupting prominences with observations using data from the AIA Filament Eruption Catalog.

Results. We find that the slow rise and impulsive phases of erupting prominences are modulated by magnetic reconnection. The transition from slow rise to acceleration results from a change from a low inflow Alfvén Mach number to a higher one. For the first time, we demonstrate that thermal conduction and compressional heating can lead to prominence evaporation. We obtain clearly nested, circular fine structures in extreme ultraviolet images of the ejected flux ropes, already present during their early evolution in the low corona. Some of this structure results directly from upward-moving plasmoids that interact with the flux rope.

Conclusions. We conclude that thermal conduction and compressional heating are highly relevant heating mechanisms in erupting flux rope interiors, and that magnetic reconnection dictates the entire early evolution of coronal mass ejections, from the slow-rise phase to the impulsive phase.