Related papers: Properties of Supersonic Evershed Downflows
The motion of dark striations across bright filaments in a sunspot penumbra has become an important new diagnostic of convective gas flows in penumbral filaments. The nature of these striations has, however, remained unclear. Here we…
We use high spatial and spectral resolution observations obtained with the CRisp Imaging SpectroPolarimeter at the Swedish 1-m Solar Telescope to analyze the velocity profile of granular light bridges in a sunspot. We find upflows…
Small-scale magnetic features are present everywhere in the solar photosphere. Theoretical models, numerical calculations, and simulations describing the formation of these features have existed for a few decades, but there are only a few…
Sunspots, which harbor both magnetic polarities within one penumbra, are called delta-spots. They are often associated with flares. Nevertheless, there are only very few detailed observations of the spatially resolved magnetic field…
We investigated the horizontal and the vertical component of the Evershed flow (EF). To this end, we computed average Stokes V profiles for various velocity classes in penumbrae at different heliocentric angles. Our results show that for…
In this paper, we analyze the high-resolution UV spectra for a C1.7 solar flare (SOL2017-09-09T06:51) observed by the \textit{Interface Region Imaging Spectrograph} (\textit{IRIS}). {We focus on the spectroscopic observations at the…
We studied the physical parameters of the penumbra in a large and fully-developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe I 617.3 nm and chromospheric Ca II…
The origin of the slow solar wind is still an open issue. One possibility that has been suggested is that upflows at the edge of an active region can contribute to the slow solar wind. We aim to explain how the plasma upflows are generated,…
We analyse spectropolarimetric observations of the penumbra of the NOAA AR 10953 at high spatial resolution (0.3"). The full Stokes profiles of the Fe I lines at 630.1 nm and 630.2 nm have been obtained with the Solar Optical Telescope…
The properties of magnetic fields forming an extended plage region in AR 10953 were investigated. Stokes spectra of the Fe I line pair at 6302 \AA recorded by the spectropolarimeter aboard the Hinode satellite were inverted using the SPINOR…
The high spatial and time resolution data obtained with SDO/AIA for the sunspot in active region NOAA 11131 on 08 December 2010 were analysed with the time-distance plot technique and the pixelised wavelet filtering method. Oscillations in…
The highly dynamic atmosphere above sunspots exhibits a wealth of magnetohydrodynamic (MHD) waves. Recent studies suggest a coupled nature of the most prominent phenomena: umbral flashes (UFs) and running penumbral waves (RPWs). From an…
Solar chromospheric observations of sunspot umbrae offer an exceptional view of magneto-hydrodynamic wave phenomena. In recent years, a wealth of wave signatures related to propagating magneto-acoustic modes have been presented, which…
In Paper by Titarchuk & Shrader the general formulation and results for photon reprocessing (downscattering) that included recoil and Comptonization effects due to divergence of the flow were presented. Here we show the Monte Carlo (MC)…
Active regions are thought to be one contributor to the slow solar wind. Upflows in EUV coronal spectral lines are routinely osberved at their boundaries, and provide the most direct way for upflowing material to escape into the…
Exploding granules have drawn renewed interest because of their interaction with the magnetic field. Especially the newly forming downflow lanes developing in their centre seem to be eligible candidates for the intensification of magnetic…
Sunspot fine structure has been modeled in the past by a combination of idealized magneto-convection simulations and simplified models that prescribe the magnetic field and flow structure to a large degree. Advancement in numerical methods…
Vector magnetic fields of moving magnetic features (MMFs) are well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focus on the evolution of three MMFs with the SOT in this study. We found that an MMF having…
Results of a 3D MHD simulation of a sunspot with a photospheric size of about 20 Mm are presented. The simulation has been carried out with the MURaM code, which includes a realistic equation of state with partial ionization and radiative…
Context. Investigations of the magnetism of the quiet Sun are hindered by extremely weak polarization signals in Fraunhofer spectral lines. Photon noise, straylight, and the systematically different sensitivity of the Zeeman effect to…