We present the results of an extensive spectroscopic survey of RX J0152.7-1357, one of the most massive distant clusters of galaxies known. Multi-object spectroscopy, carried out with FORS1 and FORS2 on the ESO Very Large Telescope (VLT), has allowed us to measure more than 200 redshifts in the cluster field and to confirm 102 galaxies as cluster members. The mean redshift of the cluster is z =...

We consider a sample of 51 distant galaxy clusters at 0.15 ∼< z ∼< 0.9 (< z >∼ 0.3), each cluster having at least 10 galaxies with available redshift in the literature. We select member galaxies, analyze the velocity dispersion profiles, and evaluate in a homogeneous way cluster velocity dispersions and virial masses. We apply the same procedures already recently applied on a sample of nearby c...

Based on the photometric survey of the inner region of the Centaurus cluster (Jerjen & Dressler 1997a) we measured redshifts for a deep, surface brightness limited sample of galaxies using the MEFOS multifibre spectrograph at the ESO 3.6m telescope. With the new data set radial velocities for 120 centrally located cluster members become available which is equivalent to 78% of all known cluster ...

We present spectroscopic observations of galaxies in 4 clusters at z = 0.7 − 0.8 and in one cluster at z ∼ 0.5 obtained with the FORS2 spectrograph on the VLT as part of the ESO Distant Cluster Survey (EDisCS), a photometric and spectroscopic survey of 20 intermediate to high redshift clusters. We describe our target selection, mask design, observation and data reduction procedures, using these...

Based on the photometric survey of the inner region of the Centaurus cluster (Jerjen &Dressler 1997a) wemeasured redshifts for a deep, surface brightness limited sample of galaxies using the MEFOS multifibre spectrograph at the ESO 3.6m telescope. With the new data set radial velocities for 120 centrally located cluster members become available which is equivalent to 78% of all known cluster ga...

We present the current results from our ongoing radial-velocity survey of the intermediate-age (2.4 Gyr) open cluster NGC 6819. Using both newly observed and other available photometry and astrometry we define a primary target sample of 1454 stars that includes main-sequence, subgiant, giant, and blue straggler stars, spanning a magnitude range of 11≤V≤16.5 and an approximate mass range of 1.1 ...

We present the current results from our ongoing radial-velocity survey of the intermediate-age (2.4 Gyr) open cluster NGC 6819. Using both newly observed and other available photometry and astrometry we define a primary target sample of 1454 stars that includes main-sequence, subgiant, giant, and blue straggler stars, spanning a magnitude range of 11≤V≤16.5 and an approximate mass range of 1.1 ...

We analyze 9 open clusters with ages in the range 70Myr to 3.2Gyr using UCAC2 proper motion data and 2MASS photometry, which allows us to reach stellar masses down to ≈ 0.7M⊙. We employ in this work an approach in which the background proper motion contribution is statistically subtracted in order to obtain the cluster’s intrinsic proper motion distribution. For each cluster we consider the pro...

By combining galaxy tracers from high-resolution N -body and hydrodynamical simulations, we present a consistent picture of the behavior of galaxy velocities in massive clusters. In haloes above ∼10M , the brightest satellite galaxies are slightly cooler compared to the dark matter, while fainter satellites are hotter. Within the virial radius of a cluster, the mean velocity dispersion based on...

Aims. We present a detailed dynamical analysis of the rich galaxy cluster A2744, containing a powerful diffuse radio halo. Methods. Our analysis is based on redshift data for 102 galaxies, part of them recovered from unexplored spectra in the ESO archive. We combine galaxy velocity and position information to select the cluster members and determine global dynamical properties of the cluster. W...