Response of the solar atmosphere to flux emergence

With emergence-driven prominence formation

¹ Max Planck Institute for Solar System Research, Göttingen D-37077, Germany
² Centre for mathematical plasma-astrophysics (CmPA), KU Leuven, Celestijnenlaan 200B, 3001 Leuven, Belgium

^⋆ Corresponding author: lixiaohong@mps.mpg.de

Received: 29 January 2025
Accepted: 29 April 2025

Abstract

Context. Flux emergence is crucial for the formation of solar active regions and the triggering of various eruptions. Observations show that solar activities including filament eruptions, jets, and flares are often associated with flux emergence. However, the detailed mechanisms by which flux emergence drives these eruptions remain unclear and require numerical investigation.

Aims. Using 2.5-dimensional magnetohydrodynamic simulations, we investigate the interaction between emerging flux and background magnetic fields and the dynamics of the induced eruptions.

Methods. Our simulations model a stratified solar atmosphere, incorporating key energy transfer mechanisms such as radiative cooling, thermal conduction, and background heating. By systematically varying the strength and angle of the emerging magnetic field relative to the background field, we investigate its impact on the initiation and evolution of solar eruptions.

Results. This study extends our previous work, in which a multithermal jet formed as emerging flux interacted with a preexisting arcade hosting coronal rain. The simulations show that magnetic reconnection between the emerging flux and the background field drives the formation of current sheets, magnetic islands, and multithermal jets. Stronger magnetic fields result in earlier eruptions, more energetic jets, and enhanced heating. The formation and ejection of magnetic islands affect the structure and dynamics of the jet. When the hot and cool components of jets reach the other footpoint of magnetic loops, they generate spicules near the transition region. Varying the angle between the emerging flux and the background field, we find that larger angles delay filament ascent and eruption timing but facilitate filament formation. Filaments form a hot shell and oscillate with a period of 10 minutes driven by periodic plasma ejections. Repetitive reconnection events inject cold plasma into the self-consistently formed filament channel, introducing a new prominence formation mechanism by flux-emergence-fed injection.

Conclusions. Our analysis highlights the dynamic interplay between magnetic reconnection, plasma cooling and heating, and filament dynamics. These findings provide insights into solar eruptions and their observational signatures, emphasizing the role of multithermal structures in the corona.