We present here a study of the Hα equivalent widths of the flocculent galaxy NGC 4395 and the grand-design galaxy NGC 5457. A difference between the mean values of the Hα equivalent widths for the two galaxies has been found. Several hypotheses are presented in order to explain this difference: differences in age, metallicity, star formation rate

The Galaxy Origins and Young Assembly (GOYA) survey is designed to study the formation and evolution of 1

We present bidimensional spectroscopy of the circumnuclear region of the Seyfert galaxy NGC 3227. The physical and kinematical characteristics of the two gaseous components reported recently by Mediavilla & Arribas are discussed. One of the components seems to be directly related to activity. We propose that it represents gas streaming from the

We present a study of the properties of radial conformal Killing fields (RCKF) in conformally flat space-times, pointing out its interest in kinematical cosmology. i) Robertson-Walker space-times are characterized as those conformally flat metrics admitting a geodesic RCKF. ii) The conformal factor of space-times that admit a RCKF with homogeneous

A new empirical model that accurately describes the inner and outer light-profiles of early-type galaxies is presented. This model effectively unites the Sérsic and Nuker models, and in so doing allows one to perform meaningful comparisons between the inner and outer properties of early-type galaxies. New and fundamental connections between a

Context. The chemical composition of stars that have orbiting planets provides important clues about the frequency, architecture, and composition of exoplanet systems. Aims: We explore the possibility that stars from different galactic populations that have different intrinsic abundance ratios may produce planets with a different overall