Oscillatory behaviour of chromospheric fine structures in a network and a semi-active region

Abstract

In this work, we study the periodicities of oscillations in dark fine structures using observations of a network and a semi-active region close to the solar disc centre. We simultaneously obtained spatially high-resolution time series of white light images and narrow-band images in the Hα line using the 2D G̈ottingen spectrometer, which were based on two Fabry-Perot interferometers and mounted in the Vacuum Tower Telescope/Observatorio del Teide/Tenerife. During the observations, the Hα line was scanned at 18 wavelength positions with steps of 125 mÅ. We computed series of Doppler and intensity images by subtraction and addition of the Hα ± 0.3 Å and ± 0.7 Å pairs, sampling the upper chromosphere and the upper photosphere, respectively. Then, we obtained power, coherence and phase difference spectra by performing a wavelet analysis to the Doppler fluctuations. Here, we present comparative results of oscillatory properties of dark fine structures seen in a network and a semi-active region. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.