A set of parameters to characterize azimuthal profiles of galaxies is proposed and applied to the spiral structure of the galaxies NGC 1832 and NGC 7479 observed in the B and I passbands. Interpretations of the observations in terms of the two most widely discussed theories of star formation, the spiral density wave theory and that of self

Spectrograms of five bright northern central stars of planetary nebulae (CSPN) are compiled in order to provide spectral descriptions of these stars, with particular attention given to the central stars of NGC 6543 and NGC 6572 (the best examples of the Of WR spectral class) and a comparison of these to less extreme Of CSPN. Results present clear

SE DENOMINAN ESTRELLAS AZULES REZAGADAS (BLUE STRAGGLERS, BS) AQUELLAS ESTRELLAS QUE EN EL DIAGRAMA COLOR-MAGNITUD (C-M) DE UN CUMULO ESTELAR SE LOCALIZAN CERCA DE SU SECUENCIA PRINCIPAL, PERO CON LUMINOSIDADES SUPERIORES A LA DEL PUNTO DEL GIRO, SEMEJANDO, POR TANTO, ESTRELLAS QUE HAN RETRASADO SU EVOLUCION RESPECTO AL RESTO DEL CUMULO. UNA DE LAS

With two photometric stations (Tenerife and Baja California) the luminosity p-mode spectrum at different wavelengths has been identified. After a coherence analysis between data from both stations to verify the solar origin of the peaks identified in luminosity, a comparative study with simultaneous velocity measurements (obtained at Tenerife only)

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Exponential filtering, together with an improved version of the iterative Fourier-transform algorithm, is applied to image reconstruction from one-dimensional infrared stellar speckle interferometry data. The only problem was an expected noisy appearance of the results when noisy data were simulated. Finally, the method was applied to observational