Dynamics of a prominence-horn structure during its evaporation in the solar corona

TL;DR

This study observes a prominence-horn structure in the solar corona, revealing oscillation behaviors and formation processes, and suggests the horn forms through heating and dilution rather than cooling and condensation.

Contribution

It provides new observational insights into the formation and dynamics of prominence-horn structures, emphasizing the role of heating and magnetic flux transport.

Findings

Large amplitude longitudinal oscillation (~150 min period) observed.

Transverse oscillation (~10-15 min period) indicates a global magnetic mode.

Horn formation linked to heating and dilution of prominence mass.

Abstract

The physical connection among and formation mechanisms of various components of the prominence-horn cavity system remain elusive. Here we present observations of such a system, focusing on a section of the prominence that rises and separates gradually from the main body. This forms a configuration sufficiently simple to yield clues to the above issues. It is characterized by embedding horns, oscillations, and a gradual disappearance of the separated material. The prominence-horn structure exhibits a large amplitude longitudinal oscillation with a period of ~150 minutes and an amplitude of ~30 Mm along the trajectory defined by the concave horn structure. The horns also experience a simultaneous transverse oscillation with a much smaller amplitude (~3 Mm) and shorter period (~10-15 minutes), likely representative of a global mode of the large-scale magnetic structure. The gradual disappearance of the structure indicates that the horn, an observational manifestation of the field-aligned transition region separating the cool and dense prominence from the hot and tenuous corona, is formed due to the heating and diluting process of the central prominence mass, while most previous studies suggest that it is the opposite process, i.e., the cooling and condensation of coronal plasmas, to form the horn. This study also demonstrates how the prominence transports magnetic flux to the upper corona, a process essential for the gradual build-up of pre-eruption magnetic energy.