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Context: Over the past years, the λ-Orionis cluster has been a prime location for the study of young very low mass stars, substellar and isolated planetary mass objects and the determination of the initial mass function and other properties of low mass cluster members. Aims: In the continuity of our previous studies of young associations cores, we

Con el trabajo desarrollado para esta tesis hemos contribuido a un avance en la investigacion de exoplanetas, obteniendo resultados muy interesantes e innovadores que nos han permitido llegar a las siguientes conclusiones: Mediante las observaciones llevadas a cabo con la red TrES, y el nodo canario STARE, y su seguimiento posterior, hemos

Context: Determining the parameters of massive stars is crucial to understand many processes in galaxies and the Universe, since these objects are important sources of ionization, chemical enrichment and momentum. 10m class telescopes enable us to perform detailed quantitative spectroscopic analyses of massive stars in other galaxies, sampling

We present an examination of high-resolution, ultraviolet (UV) spectroscopy from Hubble Space Telescope of the photospheric spectrum of the O-supergiant in the massive X-ray binary HD 226868 = Cyg X-1. We analyzed this and ground-based optical spectra to determine the effective temperature and gravity of the O9.7 Iab supergiant. Using non-LTE, line

Context: We present the results of a near-infrared photometric and spectroscopic study of the star-forming region G61.48+0.09. Aims: The purpose of this study is to characterize the stellar content of the cluster and to determine its distance, extinction, age, and mass. Methods: The stellar population was studied by using color-magnitude diagrams