Doppler Velocity and Spectral Line Width Variations in Solar Spicules and Prominences

The objective of the study is to investigate the dynamic behaviors of solar spicules and prominences and the relationship between them. An analysis of spicules and prominences and comparison of the obtained results should provide some novelty to the description of physical processes governing these phenomena. For this purpose, spectrograms in the helium D₃ line were obtained at a height of 8000 km using the large coronagraph at the Abastuman Astrophysical Observatory. The D₃ line spectrograms were derived in the second order, with an inverse dispersion of 0.96 Å/mm. The standard errors of the Doppler velocities and spectral line widths are 0.35 km/s and 0.04 Å, respectively. The lifetime of almost all measured spicules was about 20 min, which defines them as type I spicules. The Doppler shifts and variations of line widths over time were analyzed using the Lomb-Scargle periodogram algorithm for irregular data series. The primary results of the observational data reduction and analysis are as follows. The Doppler velocities in the prominence legs vary in the range of about 17–18 km/s, and in spicules in the range of 16–24 km/s. We observe a temporal asymmetry in the variation of Doppler velocities and line widths in four out of the five studied spicules. For D₃ prominences, the oscillation period of the Doppler velocities on average ranges from three to four minutes, and the period of line width oscillation from two to three minutes. For D₃ spicules, the period of Doppler velocity oscillations varies on average between two and five minutes, and the period of line width oscillation between two and five minutes. In the prominence legs, the anticorrelation between Doppler velocities and line widths is more pronounced in the region where solar plasma moves from lower atmospheric layers to higher ones. The observed anti-phase oscillations with longer periods can be explained by the upward and downward motion of turbulent plasma in type I spicules. Oscillations with shorter periods may be caused by the helical motion of the spicule axis resulting from the superposition of two linearly polarized magnetohydrodynamic kink waves.