We analyze the Hα emission line profiles of the HII region populations in three disc spiral galaxies and find evidence of wing features at 40-90 km/s from the central peak in a significant fraction of regions. We explain the wing features as due to a shell expanding inside the HII region, quantify the energy involved and present two possible

We report optical and near-infrared follow-up observations of GRB 011121 collected predominantly at ESO telescopes in Chile. We discover a break in the afterglow light curve after 1.3 days, which implies an initial jet opening angle of about 9°. The jet origin of this break is supported by the fact that the spectral energy distribution is

The Gravitational Lenses International Time Project (GLITP) collaboration observed the first gravitational lens system (QSO 0957+561) from 2000 February 3 to March 31. The daily VR observations were made with the 2.56-m Nordic Optical Telescope at Roque de los Muchachos Observatory, La Palma, Spain. We have derived detailed and robust VR light

We investigate the nuclear and global structure of early-type galaxies, and the apparent disparity between the Nuker and Sersic models for radial light profiles. We show that the so-called "power-law" galaxies in fact have Sersic r1/n profiles over their entire observed radial range. Consequently, only three (Sersic-profile) parameters are required

Over the past years observations of young and populous star clusters have shown that the stellar initial mass function (IMF) appears to be an invariant featureless Salpeter power law with an exponent α=2.35 for stars more massive than a few Msolar. A consensus has also emerged that most, if not all, stars form in stellar groups and star clusters

The near-infrared spectrograph LIRIS was first commissioned on the WHT on the nights of 15-19 Feb 2003. During all that time the instrument functioned with no major failures. At the time of commissioning LIRIS included imaging and spectroscopic observing modes. Spectroscopy could be done at low resolution (about 700 using the narrowest slit of 0.65