Related papers: Fourier analysis of active-region plage
We search for signatures of high-frequency oscillations in the upper solar photosphere and low chromosphere in the context of acoustic heating of outer stellar atmospheres. We use ultraviolet image sequences of a quiet center-disk area from…
Two sequences of solar images obtained by the Transition Region and Coronal Explorer in three UV passbands are studied using wavelet and Fourier analysis and compared to the photospheric magnetic flux measured by the Michelson Doppler…
Major solar flares are prone to occur in active region atmospheres associated with large, complex, dynamically-evolving sunspots. This points to the importance of monitoring the evolution of starspots, not only in visible but also in ultra…
Context. MHD waves are proposed to transport sufficient energy from the photosphere to heat the transition-region (TR) and corona. However, various aspects of these waves such as their nature, propagation characteristics and role in the…
In this paper, with a set of high-resolution He I 10830 \AA\ filtergrams, we select an area in a plage, very likely an EUV moss area, as an interface layer to follow the clues of coronal heating channels down to the photosphere. The…
Our aim is to search for atmospheric g-mode oscillations in UV network, UV bright points and Uv background regions. We have analysed a 6-hours of time sequence of ultraviolet (uv) images obtained on May 24, 2003 in 1600A continuum under…
Densely packed coronal loops are rooted in plages in the vicinity of active regions on the Sun. The photospheric magnetic features underlying these plages are patches of mostly unidirectional magnetic field extending several arcsec on the…
Using data from the Helioseismic Magnetic Imager, we report on the amplitudes and phase relations of oscillations in quiet-Sun, plage, umbra and the polarity inversion line (PIL) of an active region NOAA$\#$11158. We employ Fourier, wavelet…
In this study we combine the multiwavelength ultraviolet -- optical (Solar Dynamics Observatory, SDO) and radio (Nobeyama Radioheliograph, NoRH) observations to get further insight into space-frequency distribution of oscillations at…
We investigate intensity oscillations observed simultaneously in the quiet chromosphere and in the corona, above an enhanced network area at the boundary of an equatorial coronal hole. A Fourier analysis is applied to a sequence of images…
The transition region between the Sun's corona and chromosphere is important to the mass and energy transfer from the lower atmosphere to the corona; consequently, this region has been studied intensely with ultraviolet (UV) and extreme…
The strong enhancement of the ultraviolet emission during solar flares is usually taken as an indication of plasma heating in the lower solar atmosphere caused by the deposition of the energy released during these events. Images taken with…
We report and discuss phase-shift and phase travel time of low-frequency ({\nu} < 5.0 mHz) acoustic waves estimated within the photosphere and photosphere-chromosphere interface regions, utilizing multi-height velocities in the quiet Sun.…
Recurrent and propagating intensity perturbations are frequently observed in extreme ultraviolet (EUV) channels along coronal fan loops above sunspots, and these perturbations are suggested to be slow magnetoacoustic waves. Numerous studies…
We report on the physical properties of small-scale transient flows observed simultaneously at high cadence with the SUMER spectrometer and the TRACE imager in the plage area of an active region. Our major objective is to provide a better…
We search for indications of waves in the 25-2000 MHz radio spectrum of the 1 August 2010 event (SOL2010-08-01T08:57:00L075C013), where fast propagating waves in the solar corona with the periods of 181, 69, and 40 seconds were detected in…
We report decaying quasi-periodic intensity oscillations in the X-ray (6-12 keV) and extreme ultraviolet (EUV) channels (131, 94, 1600, 304 \AA) observed by the Fermi GBM (Gamma-ray Burst Monitor) and SDO/AIA, respectively, during a C-class…
We investigate the X-ray and UV emission detected by RHESSI and TRACE in the context of a solar flare on the 16th November 2002 with the goal of better understanding the evolution of the flare. We analysed the characteristics of the X-ray…
We use high spatial and temporal resolution observations, simultaneously obtained with the New Vacuum Solar Telescope and Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory, to investigate the high-frequency…
We have analysed the Ca-K images obtained at Kodaikanal Observatory as a function of latitude and time for the period of 1913 - 2004 covering the Solar Cycle 15 to 23. We have classified the chromospheric activity into plage, Enhanced…