Damped large amplitude transverse oscillations in an EUV solar prominence, triggered by large-scale transient coronal waves

Abstract

Aims. We investigate two successive trains of large amplitude transverse oscillations in an arched EUV prominence, observed with SoHO/EIT on the north-east solar limb on 30 July 2005. The oscillatory trains are triggered by two large scale coronal waves, associated with an X-class and a C-class flare occurring in the same remote active region. Methods. The oscillations are tracked within rectangular slits parallel to the solar limb at different heights, which are taken to move with the apparent height profile of the prominence to account for solar rotation. Time series for the two prominence arch legs are extracted using Gaussian fitting on the 195 Å absorption features, and fitted to a damped cosine curve to determine the oscillatory parameters.Results. Differing energies of the two triggering flares and associated waves are found to agree with the velocity amplitudes, of 50.6 ± 3.2 and 15.9 ± 8.0 km s −1 at the apex, for the first and second oscillatory trains respectively, as estimated in the transverse direction. The period of oscillation is similar for both trains, with an average of 99 ± 11 min, indicating a characteristic frequency as predicted by magnetohydrodynamics. Increasing velocity amplitude with height during the first oscillatory train, and in-phase starting motions of the two legs regardless of height, for each train, demonstrate that the prominence exhibits a global kink mode to a first approximation. However, discrepancies between the oscillatory characteristics of the two legs and an apparent dependence of period upon height, suggest that the prominence actually oscillates as a collection of separate but interacting threads. Damping times of around two to three cycles are observed. Combining our results with those of previously analysed loop oscillations, we find an approximately linear dependence of damping time upon period for kink oscillations, supporting resonant absorption as the damping mechanism despite limitations in testing this theory.

Decaying and decayless transverse oscillations of a coronal loop

“…1c), at positions X BOX = 48, 72, 96 arcsec, and Y BOX = 96, 120 arcsec, in a similar way as in previous works (e.g. Hershaw et al 2011;Verwichte et al 2004;). We calculated a mean value over the width at every position along the slit to increase the signal-to-noise ratio.…”

“…Typical periods of kink oscillations range from a few minutes to several hours (e.g. Verwichte et al 2010) (the latter case corresponds to cool fibrils of quiescent prominences, Hershaw et al 2011). In terms of magnetohydrodynamic (MHD) wave theory kink oscillations are interpreted as kink (m = 1) fast magnetoacoustic modes (e.g.…”

Large-scale Globally Propagating Coronal Waves

“…It has been argued that this could be explained in terms of a tilted wavefront (Warmuth et al, 2004b), where higher parts of the front reach the filament earlier than the lower parts that generate stronger signatures. Filament oscillations have also been detected in He i (Gilbert et al, 2008, see Figure 32) and in EUV, where transverse oscillations are observed (Hershaw et al, 2011;Asai et al, 2012;Gosain and Foullon, 2012). The latter studies showed that the transverse oscillations are caused by the impact of a fast coronal wave.…”

On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode (Invited Review)

“…Other phenomena trigerred by EUV waves are kink-like oscillations of disk filaments (Hershaw et al, 2011) and coronal loops (e.g., Wills-Davey and Aschwanden and Schrijver, 2011). The velocity of these transverse oscillations is in the range of 5-50 km s −1 , the same range as filament oscillations trigerred by Moreton waves (e.g., Gilbert et al, 2008); for a review on filamenent/prominence oscillations and their dissipation mechanisms the interested reader can refer to Arregui and Ballester (2011).…”