Desde su descubrimiento hace ya más de cincuenta años, los núcleos de galaxias activas (AGNs, del Inglés "Active Galactic Nuclei"), hospedados tanto en los centros de galaxias cercanas como en los de objetos situados a distancias cosmológicas, han despertado un creciente interés por conocer el tipo de mecanismo capaz de generar cantidades de

The neutron star X-ray transient 4U 1608-52 is often in a state of outburst (e.g. ATel #1113); the Swift/BAT light curve shows three clear outburst peaks so far in 2009. The source usually remains in a hard X-ray state during its outbursts. Here we report an X-ray state transition to a soft state around MJD 54960-75 (2009-05-09 - 24) and

Post common envelope binaries (PCEBs) consisting of a white dwarf and a main sequence star are ideal systems to calibrate current theories of angular momentum loss in close compact binary stars. The potential held by PCEBs for further development of close binary evolution could so far not be exploited due to the small number of known systems and

We present the result of the observation of the ultrafaint dwarf galaxy Willman 1 performed with the 17 m MAGIC telescope during 15.5 hr between March and May 2008. No significant γ-ray emission was found. We derived upper limits of the order of 10-12 ph cm-2 s-1 on the integral flux above 100 GeV, which we compare with predictions from several of

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Here we present multilevel radiative transfer calculations of the scattering polarization of neutral titanium lines in a three-dimensional model of the solar photosphere, which we have obtained from realistic hydrodynamical simulations of solar surface convection. We consider the particularly interesting case of the Ti I multiplet a{^5}F - y{^5}Fo