Profiles of the Na I D doublet in three bright features (clusters of umbral dots), located in a relatively dark umbra, were analyzed by means of the 'local two...

Context. Solar active regions show a wide variety of oscillatory phenomena. The presence of the magnetic field leads to the appearance of several wave modes...

For determining the adiabatic stability of a uniform vertical field in an arbitrary stratification it is sufficient to consider the limit of infinitesimal...

Aims: By focussing on the oscillations of the cross-sectional area and the total intensity of magnetic waveguides located in the lower solar atmosphere, we aim...

A description of the stray-light problem based on a radiative transfer approach is presented. The 2D convolution that describes the effect of the stray-light is...

A new procedure to separate the instrumental and atmospheric components of stray light is presented. It is based on the dependence of the aureole's atmospheric...

Context. Light bridges (LBs) are elongated structures with enhanced intensity embedded in sunspot umbra and pores. Aims: We studied the properties of a sample...

Plage areas and intensities derived from CaIIK spectroheliograms are used as a proxy for the facular irradiance excess of solar active regions for the period 19...

The joint consideration of theoretical and observational arguments is used to conclude that two different spot populations co-exist in the Sun.