Related papers: Active region fine structure observed at 0.08 arcs…
Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that…
Sunspots are concentrations of magnetic field on the visible solar surface that strongly affect the convective energy transport in their interior and surroundings. The filamentary outer regions (penumbrae) of sunspots show systematic radial…
Solar activity is controlled by the magnetic field, which also causes the variability of the solar irradiance that in turn is thought to influence the climate on Earth. The magnetic field manifests itself in the form of structures of…
Light bridges (LBs) are bright lanes that divide an umbra into multiple parts in some sunspots. Persistent oscillatory bright fronts at a temperature of $\sim$$10^5$ K are commonly observed above LBs in the 1400/1330 \AA~passbands of the…
Convective flows are known as the prime means of transporting magnetic fields on the solar surface. Thus, small magnetic structures are good tracers of the turbulent flows. We study the migration and dispersal of magnetic bright features…
Our aim is to determine the plasma properties of a coronal bright point and compare its magnetic topology extrapolated from magnetogram data with its appearance in X-ray images. We analyse spectroscopic data obtained with EIS/Hinode, Ca II…
The evolution of the physical parameters of magnetic bright points (MBPs) located in the quiet Sun (mainly in the interwork) during their lifetime is studied. First we concentrate on the detailed description of the magnetic field evolution…
We analyze several unusual filamentary structures, which appeared in the umbra of one of the sunspots in AR 11302. They do not resemble typical light bridges, neither in morphology, nor in evolution. We analyze data from SDO/HMI to…
Recent observations of sunspot light-bridges have shed new light on the fact that they are often associated with significant chromospheric activity. In particular chromospheric jets (Shimizu et al. 2009) persisting over a period of days…
The physical parameters of the sunspot are not fully understood, especially the height dependence of the magnetic field. So far, it is also an open question as to which heights the He I 1083 nm spectral line is formed at. Our aim is to…
Recent high resolution spectropolarimetric observations from Hinode detected the presence of supersonic downflows in a sunspot light bridge (Louis et al. 2009). These downflows occurred in localized patches, close to regions where the field…
Active Galactic Nuclei (AGN) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight, yet the specific inclinations of all but a few AGN are generally…
In the present 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 disk center. We simultaneously obtained spatially high resolution time…
The fine-structure of magnetic field of a sunspot penumbra in the upper chromosphere is to be explored and compared to that in the photosphere. High spatial resolution spectropolarimetric observations were recorded with the 1.5-meter GREGOR…
We study the velocity field of umbral dots at a resolution of 0.14". Our analysis is based on full Stokes spectropolarimetric measurements of a pore taken with the CRISP instrument at the Swedish 1-m Solar Telescope. We determine the flow…
Delta ($\delta$) sunspots sometimes host fast photospheric flows along the central magnetic polarity inversion line (PIL). Here we study the strong Doppler shift signature in the central penumbral light bridge of solar active region NOAA…
Finding low-mass planets around solar-type stars requires to understand the physical variability of the host star, which greatly exceeds the planet-induced radial-velocity modulation. Different solar photospheric absorption lines have…
In this work, we study and quantify properties of strong-field small-scale convection and compare observed properties with those predicted by numerical simulations. We analyze spectropolarimetric 630.25 nm data from a unipolar ephemeral…
We analyze a solar active region observed by the Hinode CaII H line using the time-distance helioseismology technique, and infer wave-speed perturbation structures and flow fields beneath the active region with a high spatial resolution.…
Relying on the assumption that the interchange convection of magnetic flux tubes is the physical cause for the existence of sunspot penumbrae, we propose a model in which the dynamical evolution of a thin magnetic flux tube reproduces the…