We present a quantitative analysis of the star formation history (SFH) of the Local Group dSph galaxy Leo I, from the information in its Hubble Space Telescope [(V-I),I] color-magnitude diagram (CMD). It reaches the level of the oldest main-sequence turnoffs, and this allows us to retrieve the SFH in considerable detail. The method we use is based

The star formation history of the dwarf elliptical galaxy NGC 185, together with its spatial variations, has been investigated for old, intermediate-age, and young stars, using new ground-based Hα and BVI photometry and synthetic color-magnitude diagrams (CMDs). We find that the bulk of the stars were formed in NGC 185 at an early epoch of its

We are conducting a multi-wavelength (radio, optical, and X-ray) observational campaign to classify, morphologically and physically, a sample of 55 flat-spectrum radio sources dominated by structure on kpc-scales. This sample contains 22 compact-/medium-sized symmetric object candidates, a class of objects thought to be in the early stages of the

We have used narrow emission-line data from the new 7C Redshift Survey to investigate correlations between the narrow-line luminosities and the radio properties of radio galaxies and steep-spectrum quasars. The 7C Redshift Survey is a low-frequency (151MHz) selected sample with a flux density limit about 25 times fainter than the 3CRR sample. By

An analysis of CCD spectra in the range lambda lambda4200 -8775, obtained at several positions of seven bright Galactic H Ii regions, with galactocentric distances in the range 6-10 kpc, is presented. Temperatures, densities and ionic abundances are calculated for all the positions, and the relative trends followed by these parameters are

En esta tesis la población estelar de las galaxias enanas del Grupo Local NGC 185 y Phoenix es investigada a partir de fotometría obtenida en telescopios en tierra y usando diagramas color-magnitud sintéticos. El principal resultado de esta tesis es que ambas galaxias presentan periodos largos de actividad de formación estelar y gradientes en sus