We present the results of a new spectroscopic and photometric survey of the hot X-ray cluster 1E0657-56, at z=0.296. We determine the presence of a low velocity dispersion subcluster, which is offset from the main cluster position by 0.7 Mpc and =~ 600 km s-1. We determine the virial masses and total luminosities of the cluster and its subcluster

We present deep L- (3.8 μm) and M- (4.7 μm) band imaging with the Infrared Spectrometer and Array Camera (ISAAC) on the ESO Very Large Telescope (VLT) with unprecedented spatial resolution of the nearby Seyfert 2 galaxies NGC 7496 and NGC 7582 and the Seyfert 1 galaxy NGC 7213, all at a comparable distance. The unresolved nuclear component

Planet accretion onto solar type stars may significantly change the stellar atmospheric abundances of 6Li and 7Li if it takes place after the star has arrived at the main sequence. Ingestion of planets at an earlier phase will not affect theses abundances because of extensive pre-main sequence mixing and burning. We present quantitative estimates

The optical morphological and photometric properties of 79 low redshift radio galaxies are discussed. It is found that most radio galaxies are luminous bulge dominated systems similar to normal non-radio giant ellipticals. The average absolute magnitude of the sample is =-23.98, with a clear trend for FR I sources to be /~0.5 mag brighter than FR

Here we attempt to infer the recent history of star formation in the BCD galaxy VII Zw 403, based on an analysis that accounts for the dynamics of the remnant generated either by an instantaneous burst or by a continuous star formation event. The models are restricted by the size of the diffuse X-ray-emitting region, the Hα luminosity from the star

The energy budget of all known optical jets is discussed. It is found that to power the extended radio lobes of radio galaxies, the jet bulk motion on kpc scales must be relativistic, on average. Based on various constraints, a ``most probable'' region centered around Γbulk~7.5 and /θ~20° is found. Because of the consequent relativistic beaming