Aims: We present constraints on the thermodynamical structure of the chromosphere from ground-based observations of the Ca ii H line profile near and off the solar limb. Methods: We obtained a slit-spectrograph data set of the Ca ii H line with a high signal-to-noise ratio in a field of view extending 20'' across the limb. We analyzed the spectra

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in january 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (~=8 years) and eccentricity (~=0.89). We provide updated values for the orbital parameters, new estimates for the WR and

The dwarf elliptical galaxies (dEs) are more luminous than dwarf spheroidals and fainter than "normal" ellipticals. In this paper I investigate the interconnection between these three families of early-type galaxies by studying their stellar populations properties. Some dwarf ellipticals have strong metallicity and age gradients, up to - 0.5 dex

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We introduce a Monte Carlo ray tracing code for soft X-ray fluorescence in particulate media. We use the code to investigate the observation geometry dependent effects on absolute fluorescence line intensities and relative line ratios due to the medium porosity, incident spectrum, and particle size distribution. In particular, we assess the

A review of the ability of asteroseismology to probe the internal physics of OB stars is presented. The main constraints that can be obtained from the frequency spectrum in p- and g-modes pulsators are discussed. Next, we consider energetic aspects of the pulsations in OB stars and show how such study also allows to constrain their internal physics