En esta tesis se aborda el estudio de los espejismos gravitatorios QSO 0957+561 y QSO 2237+0305. Para ello se ha realizado un seguimiento fotométrico de 5 años del sistema QSO 0957+561 en el telescopio IAC-80 del Observatorio de Teide. Utilizando una nueva técnica de reducción fotométrica y un nuevo método de obtención del retraso temporal, se ha

Esta tesis presenta el desarrollo y aplicación de métodos de transporte radiactivo para la investigación de Campos magnéticos en astrofísica mediante el efecto Hanle, con particular interés en los campos Magnéticos débiles de la atmósfera solar (desde 1 mililgauss hasta 11 gauss aproximadamente). En este Rango de intensidades de campo magnético es

The COMPTEL observations of the galactic 1.809 MeV emission attributed to the radioactive decay of 26Al have confirmed the diffuse nature of this interstellar emission line. One of the most significant features of the reconstructed intensity pattern is a flux enhancement towards Cygnus. This region is fairly young and contains a wealth of massive

We present high- and intermediate-resolution spectroscopy of the X-ray nova Centaurus X-4 during its quiescent phase. Our analysis of the absorption features supports a K3-K5 V spectral classification for the companion star, which contributes ~=75 per cent of the total flux at Hα. Using the high-resolution spectra we have measured the rotational

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The study of extragalactic extinction laws is of paramount importance as it plays a key role in galaxy evolution, as well as for the determination of the cosmological parameters, for example using SNe. We propose to utilize a new technique based on flux measurements of gravitationally lensed, multiply-imaged QSOs to estimate the extinction law of