Doppler-shift oscillations in solar spicules

Zaqarashvili, T. and Khutsishvili, E. and Kukhianidze, V. and Ramishvili, G. (2007) Doppler-shift oscillations in solar spicules. Astronomy and Astrophysics, 474 (2). pp. 627-632.

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Abstract

Aims:We analysed the consecutive height series of Hα spectra in solar limb spicules taken on the 53 cm coronagraph of Abastumani Astrophysical Observatory at the heights of 3800-8700 km above the photosphere. Our aim is to observe oscillatory phenomena in spicules and consequently to trace wave propagations through the chromosphere. Methods: We use the Discrete Fourier Transform analysis of Hα Doppler shift time series constructed from the observed spectra at each height. Results: Doppler velocities of solar limb spicules show oscillations with periods of 20-55 and 75-110 s. There is also clear evidence of 3-min oscillations at the observed heights. Conclusions: The oscillations can be caused by wave propagations in thin magnetic flux tubes anchored in the photosphere. We suggest the granulation as a possible source of the wave excitation. Observed waves can be used as a tool for spicule seismology, and the magnetic field strength in spicules at the height of 6000 km above the photosphere is estimated as 12{-}15 G.

Item Type: Article
Subjects: Q Science > QB Astronomy
Depositing User: Vasili Kukhianidze
Date Deposited: 25 Jan 2014 08:11
Last Modified: 27 Mar 2015 10:06
URI: http://eprints.iliauni.edu.ge/id/eprint/513

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