Context: The behaviour of both ephemeral regions and moving magnetic features has been often described for the photospheric layer, but not for the chromosphere. Both magnetic structures are related to the decay of active regions, but their actual role is not yet clear. Aims: Our aim is to observe and understand the behaviour of these structures in

Aims:The non-conservative gravitational potential of barred galaxies, or of any other non-axisymmetric structure, produces a loss of energy in infalling particles of the intergalactic medium into the galaxy, which are trapped in its potential. This dynamical friction can contribute towards increasing the total mass of barred galaxies. Methods

A consistent analysis, based on non-LTE codes with sphericity and mass loss,of different ionization species in the far-UV and UV spectra of O-type starsallowed us to constrain the long-time uncertain ionization equilibrium in thestellar winds, to quantify the role of soft X-rays from shocks and to reconcileotherwise discrepant UV line diagnostics

Aims:We present a new automatic code (ARES) for determining equivalent widths of the absorption lines present in stellar spectra. We also describe its use for determining fundamental spectroscopic stellar parameters. Methods: The code is written in C++ based on the standard method of determining EWs and is available for the community. The code

We have developed a method to measure the mirror reflectivity of telescopes. While it is relatively easy to measure the local reflectivity of the mirror material, it is not so straightforward to measure the amount of light that it focuses in a spot of a given diameter. Our method is based on the use of a CCD camera that is fixed on the mirror dish

We report time-resolved photometry of the optical counterpart to the black hole candidate SWIFT J1753.5-0127 (Palmer et al. 2005, ATel #546: Halpern et al. 2005, ATel #549). After its discovery, this source has remained in the low/hard state and bright at optical/IR wavelengths. Our analysis indicates that this X-ray transient is a short orbital