High resolution spectra containing the Mg II h and k resonance doublet have been obtained using the long wavelength spectrometer of IUE, for 7 late-type stars (F0 to G8). In one of these stars, β Hyi, two sharp absorption features were detected against the chromospheric emission cores. Using the study of Crutcher (1982) the authors can employ the

On the basis of the current knowledge about the size of the neutron, the nucleon-nucleon interaction, and the limit on the ratio Gm/c2R 4/9 imposed by General Relativity, the authors find an upper limit of about 2 M_sun;, for stars of uniform density in the neutron phase. The importance of an accurate determination of the neutron radius for

Dynamical problems associated with the orbital motion of dust particles in strong gravitational and radiation fields are analyzed. The general relativistic equations for the motion of a single dust particle are derived, and the static, spherically symmetric situation described by the Schwarzschild metric is considered. Two sharply differentiated

SE PRESENTAN OBSERVACIONES CARTOGRAFICAS Y FOTOMETRIA INTEGRAL EN EL INFRARROJO EN LAS BANDAS J H Y K DE 13 CUMULOS GLOBULARES QUE SE EXPLICAN EN BASE A UN MODELO SINTETICO DE COLORES INTEGRALES CONSTRUIDO CON RESULTADOS EMPIRICOS DE COLORES ESTELARES PARA LA POBLACION II. SE PRESENTAN OBSERVACIONES FOTOMETRICAS DE ESTRELLAS AISLADAS EN LOS CUMULOS

MODELOS DE ACELERACION DE PARTICULAS EN ONDAS DE CHOQUE POR EL MECANISMO DE FERMI DE PRIMER ORDEN SE APLICAN A JETS EN NUCLEOS GALACTICOS ACTIVOS Y CUASARES. SE SIMULAN LAS PROPIEDADES OBSERVACIONALES DE LA EMISION NO TERMICA DE LOS ELECTRONES ACELERADOS EN ONDAS DE CHOQUE EXTRAGALACTICAS RESOLVIENDO LA ECUACION DE TRANSPORTE DE RADIACION

Although the QSO PKS 2128 - 123 appears as highly variable in the I band, with Delta-I of up to 1.69 mag, it is a moderate amplitude variable object in the other bands of the present UBVRI observations. Excluding these I fluxes, the average continuum is well fitted by a power law when the Balmer continuum contribution, which enters the V band, has