Preliminary results of new high-resolution and S/N ratio spectra of central stars of planetary nebulae (CSPN) are presented. The atmospheric parameters (Teff, log g, helium abundance) are derived using NLTE techniques. The results obtained confirm the conclusions of Mendez et al. (1988): (1) the distance scale of CSPN is greater than usually

Papers are presented on stellar structure and evolution. Particular attention is given to the deep CCD photometry of stars in the globular cluster M3; dynamical instability in accreting white dwarfs; the IR photometry of open clusters; stellar mass loss in late B-type supergiants; and multicolor photopolarimetry of magnetic catalysmic variables

SE HAN PRESENTADO LOS RESULTADOS OBTENIDOS DE OBSERVAR ESPECTROSCOPICAMENTE, RESOLUCION ESPECTRAL MEDIA Y ALTA Y CON RESOLUCION ESPACIAL, 16 NEBULOSAS BIPOLARES. LA MUESTRA INCLUYE REGIONES HII (S106, S201 Y BIP14), NEBULOSAS ASOCIADAS A ESTRELLAS AE/BE DE HERBIG (LKH 233, 1548C27 Y 645CY6), PROTOPLANETARIAS (CRL 2688, CRL 618 Y M1-92) Y

Coordinated multifrequency observations of the dwarf nova SS Cygni have been performed for several years in order to study the accretion behavior of this system in particular and in general to clarify this crucial problem for cataclysmic variables. From IUE measurements, together with those from optical and IR ground based telescopes, orbital

The behavior of the elemental depletions in the ISM along lines of sight with a very low value of the average hydrogen density is examined. A simple model in the frame of the McKee-Ostriker (1977) theory has been used to estimate the line-of-sight filling factors as a function of n-bar for those interstellar phases in which a significant degree of

Complete infraredJ andK light curves of the RS CVn system XY UMa have been obtained at the beginning of 1989. We point out some interesting morphological changes observed in these light curves.