El objetivo de esta tesis es el estudio de la historia de formación de nuestra Galaxia. Para ello, hemos analizado los sistemas estelares más viejos, los cúmulos globulares, obteniendo como resultado principal el que esa formación e produjo mediante un colapso rápido del halo. La tesis se presenta en tres bloques principales. -En el primero se

The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations to provide information on the basic parameters of the stars: masses, radii, effective temperatures, ages, and

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The optical transient of the faint gamma-ray burst GRB 990308 was detected by the QUEST camera on the Venezuelan 1 m Schmidt telescope starting 3.28 hr after the burst. Our photometry gives V=18.32+/-0.07, R=18.14+/-0.06, B=18.65+/-0.23, and R=18.22+/-0.05 for times ranging from 3.28 to 3.47 hr after the burst. The colors correspond to a spectral

We derive a bound on the magnetic dipole moment of the top quark in the context of the effective Lagrangian approach by using the ratios Rb=Γb/Γh, Rl=Γh/Γl and the Z width. We take into account the vertex and oblique corrections. We obtain the allowed region for the magnetic dipole moment of top quark as -2.94

This thesis presents observational kinematic results for a significant sample of disk galaxies. Spectra of both the gaseous and stellar components are available for almost the whole sample. The first aim was to make a comparative study of the gas and the stellar kinematics to see whether there was any correlation between the kinematic behavior and