Periodic deviations from a linear ephemeris of a binary star's eclipses can indicate the presence of a third body in orbit around both. Hints for such companion around the M4.5/M4.5 binary CMDra were published by Deeg et al. (2008). The assignment of a planet in the CMDra system can however only be accepted if the earlier observed periodicity

Cluster cores are dominated by quiescent early-type galaxies, whereas the field is dominated by star-forming late-type galaxies. Galaxy properties, notably the star formation ability, are altered as they fall into overdense regions. The critical issues to understand this evolution are how the truncation of star formation is connected to the

We have been searching for surviving companions of progenitors of Galactic Type-Ia supernovae, in particular SN 1572 and SN 1006. These companion stars are expected to show peculiarities: (i) to be probably more luminous than the Sun, (ii) to have high radial velocity and proper motion, (iii) to be possibly enriched in metals from the SNIa ejecta

We present here a theoretical model which can at least contribute to the observed relation between the specific angular momenta of galaxies and their masses. This study offers prima facie evidence that the origin of an angular momentum of galaxies could be somewhat more complex than previously proposed. The most recent observations point to a

We present mid-IR observations taken with CanariCam at Gran Telescopio Canarias of the quadruply lensed quasar QSO2237+0305. We have obtained flux ratios between the four images that, unlike optical, near-IR and, to a lesser extent, radio emission, are unaffected by the ISM (extinction/scattering) or stellar microlensing. We are using these flux

In nature there are groups and clusters of galaxies that present a large difference in luminosity between their two brightest members. These galaxy aggregations are called fossils and they host the most luminous and massive galaxies in the Universe. How did fossil systems form? Which are the mechanisms driving their evolution? Which are the