We explore the behaviour of the most popular spectroscopic absorption features in the optical region as a function of the initial mass function (IMF), while taking into account the spectral resolution and galaxy velocity dispersion. We conclude that the IMF produces a negligible effect on the Lick indices contained in the wavelength interval λ 3800

H_α luminosities of a sample of galaxies in nearby compact groups are presented. Our purpose is to study the influence of the group environment on the star formation rates (SFRs) of the galaxies in the groups, provided that the H_α luminosity is a good tracer of the SFR of disc galaxies. Measuring the global L/L_B of the groups - including early

The spectroscopic parallaxes in the Hipparcos catalogue can be used to translate absolute stellar fluxes observed at Earth to the fluxes emerging at the stellar surface for nearby stars. The comparison of these fluxes with the predictions of theoretical model atmospheres allows us to determine the effective temperature and the metallicity of the

We report the detection of a bisymmetric nuclear spiral structure in the spiral galaxy NGC 5248. The two red spiral arms can be followed for about 3 arcsec, before they appear to end inside the radius of the circumnuclear starburst `ring' at about 5.5 arcsec or 400 pc distance from the nucleus. We combine our near-infrared Canada-France-Hawaii

We present an objective and automated procedure for detecting clusters of galaxies in imaging galaxy surveys. Our Voronoi Galaxy Cluster Finder (VGCF) uses galaxy positions and magnitudes to find clusters and determine their main features: size, richness and contrast above the background. The VGCF uses the Voronoi tessellation to evaluate the local

We have digitally coadded APM scans of 13 Kodak TechPan films of the SE region of the Virgo Cluster of galaxies. The ~6.2°×6.2° field of the R-band films combined with the resolution of ~2 arcsec pixel^- results in data-file sizes of about 222 MBytes. The 13 scanned films have been aligned, coadded, corrected for vignetting effects and cleaned of