Multilevel Analysis of Oscillation Motions in Active Regions of the Sun

Abstract

We present a new method that combines the results of an oscillation study made in optical and radio observations. The optical spectral measurements in photospheric and chromospheric lines of the line-of-sight velocity were carried out at the Sayan Solar Observatory. The radio maps of the Sun were obtained with the Nobeyama Radioheliograph at 1.76 cm. Radio sources associated with the sunspots were analyzed to study the oscillation processes in the chromosphere-corona transition region in the layer with magnetic field B=2000 G. A high level of instability of the oscillations in the optical and radio data was found. We used a wavelet analysis for the spectra. The best similarities of the spectra of oscillations obtained by the two methods were detected in the three-minute oscillations inside the sunspot umbra for the dates when the active regions were situated near the center of the solar disk. A comparison of the wavelet spectra for optical and radio observations showed a time delay of about 50 seconds of the radio results with respect to optical ones. This implies a MHD wave traveling upward inside the umbral magnetic tube of the sunspot. Besides three-minute and five-minute ones, oscillations with longer periods (8 and 15 minutes) were detected in optical and radio records.

arXiv comment17 pages, 9 figures, accepted to Solar Physics (18 Jan 2011). The final publication is available at http://www.springerlink.com

References in corpus (2)

• The Nature of Running Penumbral Waves Revealed
• Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode

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• Influence of the Magnetic Field on Oscillation Spectra in Solar Faculae
• Direct measurement results of the time lag of LOS-velocity oscillations between two heights in solar faculae and sunspots
• Oscillations Above Sunspots and Faculae: Height Stratification and Relation to Coronal Fan Structure
• Quasi periodic oscillations of solar active regions in connection with their flare activity - NoRH observations
• A new approach to kinetic energy flux at the different frequencies above the IRIS Bright Points
• Behaviour of oscillations in loop structures above active regions