Damping of Fast Magnetohydrodynamic Oscillations in Quiescent Filament Threads

TL;DR

This paper investigates how resonant absorption causes rapid damping of fast MHD oscillations in solar filament threads, highlighting the role of plasma inhomogeneity in energy dissipation.

Contribution

It demonstrates that transverse inhomogeneity in filament plasma can explain the quick damping of observed fast MHD oscillations through resonant absorption.

Findings

Damping times are a few oscillation periods.

Resonant absorption is effective in filament plasma.

Inhomogeneity influences wave attenuation.

Abstract

High-resolution observations provide evidence about the existence of small-amplitude transverse oscillations in solar filament fine structures. These oscillations are believed to represent fast magnetohydrodynamic (MHD) waves and the disturbances are seen to be damped in short timescales of the order of 1 to 4 periods. In this Letter we propose that, due to the highly inhomogeneous nature of the filament plasma at the fine structure spatial scale, the phenomenon of resonant absorption is likely to operate in the temporal attenuation of fast MHD oscillations. By considering transverse inhomogeneity in a straight flux tube model we find that, for density inhomogeneities typical of filament threads, the decay times are of a few oscillatory periods only.