Small-scale oscillations in a quiescent prominence observed by HINODE/SOT

Abstract

Context. Investigations of the behavior of small-scale threads can provide an alternative approach to studying prominence dynamics and understanding its origin and nature. Aims. The behavior of threads are analyzed in a quiescent prominence, including drifting and both the horizontally and vertically oscillating motions. These indicate waves in the solar prominence. Methods. We used the Hα images at a setting wavelength of +0.076 Å. A quiescent prominence was observed by HINODE/SOT on 2008 January 15 for about 3 h in total. Results. Consistent with previous findings, prominences show numerous thread-like structures. Some threads clearly exhibit both vertically and horizontally oscillatory motions, while others are only drifting. Complicated cases show both drifting and oscillatory motions simultaneously. In the upper part of the prominence, the threads are oscillating independently of each other. We find that three threads oscillate with the same phase for at least two periods. The oscillations seem to be strongly damped since they disappear after a few periods. The maximum number of observed periods is 8 in our observations. In the lower part of the prominence, however, the different threads have a mixed character with the individual oscillatory motions unstable for one entire period. Most oscillatory motions will disappear after a half period or less, while the new oscillatory motions are excited nearby. A 5-min period is predominant, and the oscillating amplitudes show an average value of ±3.5 km s −1 . We find some upflows in the spicule layer, and they appear to transport the mass from photosphere (or spicules themselves) to the prominence. These upflows have an average velocity amplitude of 0.8 km s −1 . Conclusions. The threads exhibit three distinct behaviors. The first is only drifting, the second is typically oscillating, and the third shows both characteristics. There are no substantial differences between the periods of horizontally and vertically oscillating threads in this prominence.

Time damping of non-adiabatic magnetohydrodynamic waves in a partially ionised prominence medium: Effect of a background flow

“…Similar results have been obtained recently by Mashnich et al (2009). The same behavior is found in high-resolution Doppler time series from individual filaments threads (Lin 2004) and in Hinode/SOT observations by Ning et al (2009a) who reported a maximum number of 8 periods before the oscillations disappeared. More extense reviews about the damping of small-amplitude prominence oscillations can be found in Oliver (2009), Ballester (2010) and Arregui & Ballester (2010).…”

Oscillatory motions observed in eruptive filaments

“…Ning et al (2009) report threads in prominences exhibiting vertical and horizontal motions from Hinode/SOT observations close to the Hα line centre at 6563+0.076 Å, and the predominant period of the small-amplitude velocity oscillations is about five minutes. Berger et al (2010) have recently reported smallscale turbulent upflows in quiescent prominences observed with Hinode/SOT, in the Ca II H line at 3969 Å and the Hα line at 6563 Å.…”

“…Wiehr et al 1989;Molowny-Horas et al 1998;Terradas et al 2002;Vršnak et al 2007;Ning et al 2009) have discussed damped oscillations in quiescent filaments, disappearing after a few periods, i.e. quickly damped by one or several mechanisms (Oliver 2009).…”

Physics of Solar Prominences: II—Magnetic Structure and Dynamics

“…Reference Period (min) Blanco et al (1999) 1 -6 Régnier et al (2001) 5 -65 Foullon et al (2004) 720 Pouget et al (2006) up to 360 Okamoto et al (2007) 2 -4.5 20 -40 Ning et al (2009) 3.5 -6…”