Related papers: Downflows in sunspot umbral dots
We investigated the vertical penumbral plasma flow on small spatial scales using data recorded by the spectropolarimeter of the solar optical telescope onboard Hinode. To this end we computed maps of apparent Doppler velocities by comparing…
The flows in and around sunspots are rich in detail. Starting with the Evershed flow along low-lying flow channels, which are cospatial with the horizontal penumbral magnetic fields, Evershed clouds may continue this motion at the periphery…
We study supersonic Evershed downflows in a sunspot penumbra by means of high spatial resolution spectropolarimetric data acquired in the Fe I 617.3 nm line with the CRISP instrument at the Swedish 1-m Solar Telescope. Physical observables,…
We discuss NICOLE inversions of Fe I 630.15 nm and 630.25 nm Stokes spectra from a sunspot penumbra recorded with the CRISP imaging spectropolarimeter on the Swedish 1-m Solar Telescope at a spatial resolution close to 0.15". We report on…
Downflows with high velocities occur in the transition region above many sunspots; however, how these signatures evolve over short time-scales in both spatial and spectral terms is still unknown. In this article, we investigate the…
The umbral oscillations of velocity are commonly observed in the chromosphere of a sunspot. Their sources are considered to be either the external p-mode driving or the internal excitation by magnetoconvection. Even though the possibility…
We present spectropolarimetric analysis of umbral dots and a light bridge fragment that show dark lanes in G-band images. Umbral dots show upflow as well as associated positive Stokes V area asymmetry in their central parts. Larger umbral…
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…
The moat flow, a radial outflow surrounding fully fledged sunspots, is a well characterised phenomenon. Nevertheless, its origin and especially its relation to the penumbra is still a controversial topic. We investigate the evolution of the…
High resolution and seeing-free spectroscopic observation of a decaying sunspot was done with the Solar Optical Telescope aboard Hinode satellite. The target was NOAA 10944 located in the west side of the solar surface from March 2 to March…
Rapid magnetic upflows in the quiet-Sun photosphere were recently uncovered from both SUNRISE/IMaX and Hinode/SOT observations. Here, we study magnetic upflow events (MUEs) from high-quality, high- (spatial, temporal, and spectral)…
Recent progress in theoretical modeling of a sunspot is reviewed. The observed properties of umbral dots are well reproduced by realistic simulations of magnetoconvection in a vertical, monolithic magnetic field. To understand the penumbra,…
High resolution spectropolarimetric observations of 3 sunspots taken with Hinode demonstrate the existence of supersonic downflows at or close to the umbra-penumbra boundary which have not been reported before. These downflows are confined…
The Hinode satellite opens a new era to the sunspots research, because of its high spatial resolution and temporal stability. Fine scale structures in sunspots, called umbral dots (UDs), have become one of the hottest topics in terms of the…
Proper motions in a sunspot group with a delta-configuration and close to the solar disc center have been studied by employing local correlation tracking techniques. The analysis is based on more than one hour time series of G-band images.…
Data analysis of sunspot oscillation based on 6-hr SDO run of observation showed that low frequency (0.2 < ! < 1 mHz) oscillations are local similar to three and five minute oscillations. The oscillations in the sunspot are concentrated in…
Recent numerical simulations of sunspots suggest that overturning convection is responsible for the existence of penumbral filaments and the Evershed flow, but there is little observational evidence of this process. Here we carry out a…
We report three-minute oscillations in the solar chromosphere driven by a strong downflow event in a sunspot. We used the Fast Imaging Solar Spectrograph of the 1.6 m New Solar Telescope and the Interface Region Imaging Spectrograph (IRIS).…
An active region filament in the upper chromosphere is studied using spectropolarimetric data in He I 10830 A from the GREGOR telescope. A Milne-Eddingon based inversion of the Unno-Rachkovsky equations is used to retrieve the velocity and…
We perform NLTE inversions in a large set of umbral flashes, including the dark fibrils visible within them, and in the quiescent umbra by using the inversion code NICOLE on a set of full Stokes high-resolution Ca II 8542 A observations of…