Formation and Immediate Deformation of a Small Filament Through Intermittent Magnetic Interactions

TL;DR

This study shows that small solar filaments form and deform primarily through intermittent magnetic interactions, such as flux emergence, cancellation, and reconnection, rather than gradual energy buildup.

Contribution

It provides detailed observational evidence linking filament formation and deformation to intermittent magnetic interactions in active regions.

Findings

Filament formation is associated with emergence and cancellation of magnetic flux.

Intermittent magnetic reconnections cause immediate filament deformation.

Magnetic activities drive both formation and deformation processes.

Abstract

It is generally believed that filament formation involves a process of the accumulation of magnetic energy. However, in this paper we discuss the idea that filaments will not erupt and will only deform when the stored magnetic energy is released gradually. Combining high-quality observations from Solar Dynamics Observatory and other instruments, we present the formation and immediate deformation of a small filament (F1) in the active region (AR) 12760 on 28-30 April 2020. Before the filament formation, three successive dipoles quickly emerged with separation motions in the center of AR 12760. Due to the magnetic interaction between magnetic dipoles and pre-existing positive polarities, coronal brightenings consequently appeared in the overlying atmosphere. Subsequently, because of the continuous cancellation of magnetic flux that happened around the adjacent ends of F1 and another nearby filament (F2), the magnetic reconections occurred intermittently occurred between F1 and F2. Finally, F1 lessened in the shear, and F2 became shorter. All the results show that the formation of F1 was closely associated with intermittent interactions between the sequence of emerging dipoles and pre-existing magnetic polarities, and the immediate deformation of F1 was intimately related to intermittent interactions between F1 and F2. We also suggest that the intermittent magnetic interactions driven by the continuous magnetic activities (magnetic-flux emergence, cancellation, and convergence) play an important role in the formation and deformation of filaments.