We derived photospheric parameters, mass-loss rates, and wind velocities of Galactic O6-O7 stars by analyzing high-resolution spectra in the far-UV and UV ranges with line-blanketed, hydrodynamic, non-LTE spherical models. We combined spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE) in the range 905-1187 Å and International

Two data series of disk integrated solar irradiance, taken by the Variability of the solar IRradiance and Gravity Oscillations (VIRGO) experiment on board the Solar and Heliospheric Observatory (SoHO) mission, corresponding to epochs of minimum and maximum solar activity have been analysed in order to study the background signal of the associated

We obtained simultaneously recorded time series of broadband images of a sunspot close to the disk center at the German Vacuum Tower Telescope, Tenerife, in two wavelength bands at 0.56 μm and 1.55 μm. Maps of brightness difference images Tb(1.55 μm) and Tb(0.56 μm) were computed for the best image pairs. Furthermore, a scatter plot of the

Some observations suggest that quiescent solar prominences can be considered as composed by small-scale loops, or fibrils, which are stacked one after another in both the vertical and horizontal directions. In a previous work we studied, in Cartensian geometry, the propagation of fast MHD waves in a two-dimensional magnetostatic model representing

We present a deep, wide-field optical survey of the young stellar cluster Alpha Per, in which we have discovered a large population of candidate brown dwarfs. Subsequent infrared photometric follow-up shows that the majority of them are probable or possible members of the cluster, reaching to a minimum mass of 0.035 Msun. We have used this list of

The theoretical understanding of the linear standing or propagating magnetohydrodynamic (MHD) waves in a variety of solar coronal structures is far from complete since analytical solutions to the linearised MHD equations can only be found for very simple magnetic configurations. In this work, a numerical code is used to solve the linear MHD wave