The morphological characteristics of corrugations in the disk shapes of the edge-on galaxies NGC 4244 and 5023 are described to determine some of the properties of these features. The corrugations are found to have a 'central' area of high corrugation and wavelike structures of increasing wavelengths emanating from the 'central' zone. If warps have

Not Available

This document updates and extends the photographic catalog of selected planetary size comparisons. It utilizes photographs taken by NASA spacecraft to illustrate size comparisons of planets and moons of the solar system. Global views are depicted at the same scale, within each comparison, allowing size relationships to be studied visually.

In this paper we report the results of simultaneous observations, using rapid continuous differential photometry, of the δ Scuti star 63 Her and of a normal main sequence F2V star, HD 155543. These observations, which lasted three weeks, in May-June 1987, were performed at the 1.5 m telescopes of the "Observatorio del Teide", in Tenerife (Spain)

The results of optical spectroscopy and photometry of V404Cyg, the optical counterpart of the recently discovered X-ray transient GS2023 + 338, are presented. Optical spectra were obtained at the Roque de los Muchachos Observatory with the 2.5-mm Isaac Newton Telescope. The overall optical light curve was found to be similar to that of an earlier

SE COMIENZA CON UNA DESCRIPCION DE LOS PROBLEMAS MAS IMPORTANTES QUE APARECEN EN EL ESTUDIO DE LAS POBLACIONES ESTELARES, ASI COMO DE LOS METODOS EMPLEADOS HASTA AHORA PARA SU TRATAMIENTO. A PARTIR DE ESTA INTRODUCCION SE MUESTRAN LOS MODELOS DESARROLLADOS EN ESTE TRABAJO, DETALLANDO TANTO LOS METODOS MATEMATICOS COMO LAS IDEAS FISICAS SOBRE LAS