Aims: We aim at constraining evolutionary models at low mass and young ages by identifying interesting transiting system members of the nearest OB association to the Sun, Upper Scorpius (USco), which has been targeted by the Kepler mission. Methods: We produced light curves for M-dwarf members of the USco region that has been surveyed during the

We study the population of asymptotic giant branch (AGB) stars in the Small Magellanic Cloud (SMC) by means of full evolutionary models of stars of mass 1 M⊙ ≤ M ≤ 8 M⊙, evolved through the thermally pulsing phase. The models also account for dust production in the circumstellar envelope. We compare Spitzer infrared colours with results from

We present an analysis of the nuclear infrared (IR, 1.6-18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3-0.5 arcsec) imaging using the Si-2 filter (λC = 8.7 μm) and 7.5-13 μm spectroscopy taken with

The solar atmosphere has been studied for decades by means of observations, theory and numerical simulations. However, due to its complexity, it is difficult to fully understand all the phenomena taking place in the atmosphere. Starting from the photosphere up to the corona, the solar atmosphere is strongly stratified and the magnetic fields

El objetivo de esta tesis es el estudio sismológico de estrellas de tipo solar en sistemas binarios eclipsantes. Las estrellas binarias son los únicos sistemas en los que podemos conocer los parámetros globales de las estrellas que los componen, tales como masa y radio, con una buena precisión. Conocer estas propiedades es importante a la hora de

We report on the analysis of the Chandra-ACIS data of O, B, and WR stars in the young association Cyg OB2. X-ray spectra of 49 O-stars, 54 B-stars, and 3 WR-stars are analyzed and for the brighter sources, the epoch dependence of the X-ray fluxes is investigated. The O-stars in Cyg OB2 follow a well-defined scaling relation between their X-ray and