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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…
We study the temporal evolution of downflows observed at the lateral edges of penumbral filaments in a sunspot located very close to the disk center. Our analysis is based on a sequence of nearly diffraction-limited scans of the Fe I 617.3…
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…
In this work we selected one particular fibril from a high resolution solar chromosphere observation from the Dutch Open Telescope, and tried to obtain a broad picture of the intricate mechanism that might be incorporated in the multiple…
Aims. In this paper, we aim to study the time dependence of sunspot group areas in a large sample composed of various databases spanning over 130 years, used state-of-the-art statistical methods. Methods. For a carefully selected but…
Sunspots are regions of decreased brightness on the visible surface of the Sun (photosphere) that are associated with strong magnetic fields. They have been found to be locations associated with solar flares, which occur when energy stored…
Sunspots are transient, magnetically intense features that host oscillations linked to magnetohydrodynamic (MHD) waves. These waves may contribute to plasma heating and drive mass flows in the solar wind. Beyond their energetic role, they…
High-resolution spectropolarimetric observations of active region NOAA 11271 were obtained with the spectro-polarimeter on board Hinode to analyze the properties of an anomalous flow in the photosphere in a sunspot penumbra. We detect a…
From the previous study (Hiremath 2009b; Hiremath 2010), on the genesis of solar cycle and activity phenomena, it is understood that sunspots are formed at different depths by superposition of Alfven wave perturbations of a strong toroidal…
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…
Discovered in 1909 the Evershed effect represents strong mass outflows in sunspot penumbra, where the magnetic field of sunspots is filamentary and almost horizontal. These flows play important role in sunspots and have been studied in…
We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end we use the magnetic and velocity fields in a horizontal layer near the…
The uncombed penumbral model explains the structure of the sunspot penumbra in terms of thick magnetic fibrils embedded in a magnetic surrounding atmosphere. This model has been successfully applied to explain the polarization signals…
Solar pores are active regions with large magnetic field strengths and apparent simple magnetic configurations. Their properties resemble the ones found for the sunspot umbra although pores do not show penumbra. Therefore, solar pores…
The striking similarity between the cyclic equatorward migration of the torsional oscillation belts and the sunspot activity latitudes inspired several attempts to seek an explanation of the torsional phenomenon in terms of interactions…
Context. Sunspot boundaries are commonly outlined by contours of the continuum intensity. However, their magnetic nature has not yet been fully characterised. Aims. We investigate the properties of the outer boundary of a long-lived sunspot…
The morphological asymmetry of leading and following sunspots is a well-known characteristic of the solar surface. In the context of large-scale evolution of the surface magnetic field, the asymmetry has been assumed to have only a…
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…
In this paper, we explore the evolution of sunspot latitude distribution and explore its relations with the cycle strength. With the progress of the solar cycle, the distributions in two hemispheres from mid-latitudes propagate toward the…
We consider a thin and narrow rectangular plate where the two short edges are hinged whereas the two long edges are free. This plate aims to represent the deck of a bridge, either a footbridge or a suspension bridge. We study a nonlocal…