An analysis of the 5 minute oscillation in the solar photosphere has been carried out using an inversion of the radiative transfer equation applied to a time-series of K I lambda 7699 line spectra with a 5" x 5" window at disk center. A thorough discussion of the inversion conditions, with special emphasis on the LTE approach and a careful error

In the context of a more extensive project, a study of the structural components of the barred spiral galaxy NGC 5850 is presented here, using U, B, V, R, and I photometry. After subtracting a bulge+disk model from the observed image, we obtain the bars, rings and other non-axisymmetric structures. We fit two-dimensional analytic functions for each

Context. Knowledge of the intrinsic shapes of galaxy components provides crucial information when constraining phenomena driving their formation and evolution. Aims: We analize the structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb galaxies to derive the intrinsic shape of their bulges. Methods: We developed a new method to

Context: The chemical composition of the gas in galaxies over cosmic time provides a very important tool for understanding galaxy evolution. Although there are many studies at high redshift, they are rather scarce at lower redshifts. However, low redshift studies can provide important clues about the evolution of galaxies, furnishing the required

We are carrying out a project for studying all the Second Byurakan Survey (SBS) interacting systems of galaxies at z 0.1. The objectives of this project are: (1) to link the histories of the star formation and nuclear activity in these systems with the morphologic type of the interacting galaxies; (2) to settle upper limits to the age of the

Results concerning the dependence of photometric and radial velocity amplitudes on metallicity are presented based on about 200 Galactic classical Cepheids pulsating in the fundamental mode. The Galactic distribution of the [Fe/H] value of Cepheids is also studied. We show that the photometric amplitude ratio AI/AV is independent of metallicity