Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal heating. At present, we can see only ~1 per cent of the complex magnetism of the quiet Sun, which highlights

En esta tesis se presenta el análisis detallado de tres galaxias ultraluminosas infrarrojas (en ingles ULIRGs) mediante los datos de espectroscopia de campo integral e imagen de alta resolución en varios filtros. Estas galaxias presentan una estructura morfológica, cinemática y de ionización extensa y bastante compleja, por lo que la espectroscopia

We present first results of the X-ray spectral analysis of 500 ksec deep survey images obtained with XMM-Newton on the Chandra Deep Field South (CDFS). Statistical distributions of spectral index and intrinsic absorption are derived for a sample containing 70 sources with a count limit of 100 (flux limit in the 2-10 keV band of 8.9×10-16 erg cm-2s

GRB 020321 is a faint GRB that received wide follow-up attention in X-rays (BeppoSAX/NFI, Chandra/ACIS-S, XMM-Newton), radio (ATCA) and optical (ESO, HST). We identify a weak X-ray afterglow by a combined study of the Chandra and XMM-Newton observations. Its decay index of 1.2 is typical for GRB afterglows. Inside the 4 arcsec accurate error box

We present new UBVI CCD observations of the old LMC globular cluster RETICULUM. These data allowed us to re-determine periods and light curves and to identify 4 double mode RR Lyrae stars. A comparison with the theoretical instability strip in the M_V-log P plane shows good agreement between theory and observations when an apparent distance modulus

We investigate the improved detection of extrasolar planets around eclipsing binaries using eclipse minima timing and extrasolar moons around transiting planets using transit timing offered by the upcoming COROT (ESA, 2005), Kepler (NASA, 2007), and Eddington (ESA 2008) spacecraft missions. Hundreds of circum-binary planets should be discovered and