We present near-infrared photometry and optical spectroscopy of very low mass stars and brown dwarf candidates in the Pleiades open cluster. The membership status of these objects is assessed using color-magnitude diagrams, lithium and spectral types. Eight objects out of 45 appear to be nonmembers. A search for companions among 34 very low mass

We present a preliminary analysis of ISO-SWS spectra of a sample of Vega-type and pre-main sequence stars, which were observed from the ground in a project devoted to the study of formation and evolution of planetary systems, carried out during the 1998 International Time of the Canary Islands Observatories. ISO-SWS covers many interesting features

En este trabajo de Tesis Doctoral se analizan y modelizan los diferentes aspectos que tienen influencia en la calidad de imagen de telescopios con espejo primario segmentado. Este trabajo, que se enmarca en el entorno del diseño y construcción del Gran Telescopio de Canarias (GTC), particulariza su desarrollo para el esquema de segmentación del GTC

An optimal window for image analysis is determined by means of information theory. The size of the window is then used as a good estimator of image quality. The method is sensitive to the size of the structures present in the image (contrary to the contrast method, widely used to select the best images of a series) and can provide a quality map

From an H-α image of the spiral barred galaxy NGC 3359, an HII region catalogue is composed. The catalogue comprises the position, mean radius and the calibrated H-alpha luminosity of each HII region. The observations of the image of NGC 3359 in H-α were carried out in February 1996, on the Isaac Newton telescope in La Palma in the context of the

We have developed a new diagnostic tool for the study of gamma-ray emission lines from radioactive isotopes (such as 26Al and 60Fe) in conjunction with other multi-wavelength observables of Galactic clusters, associations, and alike objects. Our evolutionary synthesis models are based on the code of \cite{CMH94}, which has been updated to include