Oscillatory motions observed in eruptive filaments

Abstract

Context. The origin of the variable component of the solar wind is of great intrinsic interest for heliophysics and spaceweather, e.g. the initiation of coronal mass ejections and the problem of mass loss of all stars. It is also related to the physics of coronal neutral sheets and streamers, which occur above lines of magnetic polarity reversal. Filaments and prominences correspond to the cool coronal component of these regions. Aims. We examine the dynamical behaviour of these structures where reconnection and dissipation of magnetic energy in the turbulent plasma are occurring. The link between the observed oscillatory motions and the eruption occurrence is investigated in detail for two different events. Methods. Two filaments were analysed using two different datasets: time series of spectra using a transition region line (He I at 584.33 Å) and a coronal line (Mg X at 609.79 Å) measured with CDS on-board SOHO, observed on May 30, 2003, and time series of intensity and velocity images from the NSO/Dunn Solar Telescope in the Hα line on September 18, 1994 for the other. The oscillatory content was investigated using Fourier transform and wavelet analysis and compared to different models. Results. In both filaments, oscillations are clearly observed, in intensity and velocity in the He I and Mg X lines, in velocity in Hα, with similar periods from a few minutes up to 80 min, with a main range from 20 to 30 min, simultaneously with eruptions. Both filaments exhibit vertical oscillating motions. For the filament observed in the UV (He I and Mg X lines), we provide evidence of damped velocity oscillations, and for the filament observed in the visible (Hα line), we provide evidence that parts of the filament are oscillating, while the filament is moving over the solar surface, before its disappearance.

Observations and simulations of longitudinal oscillations of an active region prominence

“…Therefore, based on this line of thought and spectroscopic observations of an oscillating prominence prior to eruption, Chen et al (2008) proposed that long-time prominence oscillations can be considered as one of the precursors of CME eruptions. A prominence oscillation prior to eruption was also observed by Bocchialini et al (2011), and the oscillation was even able to be sustained until the eruption phase (Isobe & Tripathi 2006;Gosain et al 2009). The restoring force in this kind of transverse oscillations was generally thought to be the magnetic tension force.…”

Transverse oscillations and stability of prominences in a magnetic field dip

“…(9) and (13) allow for seismological diagnostics of the current in the prominence. For example, taking a typical value of P KR ≈ 20 min (Kuperus & Raadu 1974) and fixing h = 0.6 d, for the observed periods of the vertical transverse oscillations, P z ≈ 80 min (Bocchialini et al 2011), the prominence current i with respect to the photospheric current I, according to Eq. (9), can be estimated as I ≈ 0.94 i.…”

“…Both vertically (e.g. Bocchialini et al 2011;Kim et al 2014) and horizontally polarised (e.g. Kleczek & Kuperus 1969;MolownyHoras et al 1997;Tripathi et al 2009) motions of prominences have been observed.…”

Oscillations in solar jets observed with the SOT of Hinode: viscous effects during reconnection

“…Outside of active regions coronal oscillations were reported off-disk in the range of 5 min periods (Tsubaki, 1977;Tomczyk et al 2007) and also at shorter periods (Koutchmy et al 1983). Evidences of such dynamical processes were also reported for eruptive filaments (e.g., Bocchialini et al 2011), and magnetoacoustic waves were recorded on-disk inside an anomalously bright network rosettes using simultaneous observations in 3 photospheric and chromospheric lines (Baudin et al, 1996). When considering a higher spatial resolution, even finer scales and faster variations are observed (Cirtain et al 2013).…”