Damping of filament thread oscillations: effect of the slow continuum

TL;DR

This study investigates how the slow continuum affects the damping of transverse oscillations in solar filament threads, finding that slow resonance contributes less to damping than Alfven resonance, with implications for solar prominence dynamics.

Contribution

First analytical and numerical analysis of slow continuum effects on kink mode damping in filament threads, expanding understanding of wave damping mechanisms in solar prominences.

Findings

Slow resonance damping is less efficient than Alfven resonance.

Kink mode damping times are primarily governed by Alfven continuum.

The presence of slow continuum has a minor impact on damping efficiency.

Abstract

Transverse oscillations of small amplitude are commonly seen in high-resolution observations of filament threads, i.e. the fine-structures of solar filaments/prominences, and are typically damped in a few periods. Kink wave modes supported by the thread body offer a consistent explanation of these observed oscillations. Among the proposed mechanisms to explain the kink mode damping, resonant absorption in the Alfven continuum seems to be the most efficient as it produces damping times of about 3 periods. However, for a nonzero-beta plasma and typical prominence conditions, the kink mode is also resonantly coupled to slow (or cusp) continuum modes, which could further reduce the damping time. In this Letter, we explore for the first time both analytically and numerically the effect of the slow continuum on the damping of transverse thread oscillations. The thread model is composed of a homogeneous and straight cylindrical plasma, an inhomogeneous transitional layer, and the homogeneous coronal plasma. We find that the damping of the kink mode due to the slow resonance is much less efficient than that due to the Alfven resonance.