PARTIENDO DE UNA OBSERVACION EN EL CUMULO DE COMA AFECTUADA POR EL SATELITE EXOSAT DURANTE SU FASE DE VERIFICACION DE CARACTERISTICAS SE PUDO OBSERVAR LA GRAN DENSIDAD DE FUENTES DE RAYOS X DESCONOCIDA EN ESE CAMPO. A PARTIR DE ESTOS RESULTADOS PREVIOS SE OBTUVO TIEMPO PARA EFECTUAR OTRA OBSERVACION MAS LARGA EN LA MISMA REGION EN 1985. EL ANALISIS

EN ESTE TRABAJO SE REALIZA UN ANALISIS DE LA ESTRUCTURA HIPERFINA DE LOS MODOS ACUSTICOS SOLARES A PARTIR DE DATOS OBTENIDOS CON UN ESPECTROMETRO POR SCATTERING RESONANTE EN PERIODOS ESTIVALES DE OBSERVACION A LO LARGO DE CASI UN CICLO DE ACTIVIDAD SOLAR. A PARTIR DE ESTE ESTUDIO SE OBTIENE EL TIEMPO DE VIDA DE LOS MODOS ACUSTICOS SOLARES DE BAJO

CCD UBV photometry of 2279 stars in Sextans A is presented. Differences with the photometric scales of Sandage and Carlson (1985) and Hoessel et al. (1983) are discussed; recalibration of the Sandage and Carlson data for Cepheids in Sextans A results in a smaller value for the distance modulus, μ = 25.6. A similar value for the distance modulus is

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Limits to the total mass-loss in red giants in globular clusters are calculated on the basis of Sweigart and Gross (1976) Horizontal Branch models by means of Sweigart and Gross (1978) Red Giant Branch stellar models. The upper limit is obtained through the condition that the stars do not leave their nuclei bare. The lower limit results from the

The authors have used high resolution IUE spectra from their own studies and from the archive to examine the Mg II h and k chromospheric emission cores of a sample of late-type dwarfs and giants. Sharp photospheric absorptions were used to provide a velocity rest-frame with respect to each stellar photosphere with the IUE-limited precision of ±4 km