Related papers: Infalling groups and galaxy transformations in the…

We present a study of the globular cluster systems of four early-type poststarburst galaxies using deep g and I-band images from the ACS camera aboard the Hubble Space Telescope (HST). All the galaxies feature shells distributed around…

We perform a morphological study of 124 spectroscopically confirmed cluster galaxies in the z=0.84 galaxy cluster RX J0152.7-1357. Our classification scheme includes color information, visual morphology, and 1-component and 2-component…

Using wide baseline broad-band photometry, we analyse the stellar population properties of a sample of 72 galaxies, spanning a wide range of stellar masses and morphological types, in the nearby spiral-rich and dynamically young galaxy…

We examine the origins of the bimodality observed in the global properties of galaxies around a stellar mass of 3x10^10 M_sun by comparing the environmental dependencies of star-formation for the giant and dwarf galaxy populations. The…

We present a detailed study of a rich galaxy cluster at z=2.38. We demonstrate that this cluster contains large overdensities of damped Ly-alpha absorption lines, of Ly-alpha emitting galaxies and of extremely red objects. The overdensity…

We present a study of the stellar populations of galaxies in the cluster RXJ0152.7-1357 at a redshift of 0.83. The study is based on new high S/N spectroscopy of 29 cluster members covering the wavelength range 5000-10000A as well as r'i'z'…

We present a photometric study of star clusters in the nearby starburst galaxy M82 based on the UBVI, YJ and H band Hubble Space Telescope images. We find 1105 star clusters with V<23 mag. 1070 of them are located in the disk region, while…

We present a multi-wavelength study of galaxy populations in the core of the massive, X-ray luminous cluster XMMU J2235 at z=1.39, based on VLT and HST optical and near-infrared photometry. Luminosity functions in the z, H, and Ks bands…

We investigate the possible presence of systematic rotation in the member galaxies of a sample of 17 nearby ($z<0.1$), rich (at least 80 identified members) Abell clusters. We also assess the extent to which low-number statistics may…

We present a deep UBI CCD survey using the Palomar 5-m telescope of a sample of high X-ray luminosity, distant clusters selected from the ROSAT All-Sky Survey. The 10 clusters lie at z=0.22-0.28, an era where evolutionary effects have been…

We derive ages, metallicities and [alpha/Fe] ratios from the integrated spectra of 23 globular clusters in M31, by employing multivariate fits to two stellar population models. In parallel we analyze spectra of 21 Galactic globular clusters…

We present a study of the distribution of AGN in clusters of galaxies with a uniformly selected, spectroscopically complete sample of 35 AGN in eight clusters at z = 0.06 to 0.31. We find that the 12 AGN with L_X > 10^42 erg/s in galaxies…

Brightest Cluster Galaxies (BCGs) residing in the centers of galaxy clusters are typically quenched giant ellipticals. A recent study hinted that star-forming galaxies with large disks, so-called superluminous spirals and lenticulars, are…

We present a study of galaxies in the Abell 901/902 Supercluster at z~0.165, based on HST ACS F606W, COMBO-17, Spitzer 24um, XMM-Newton X-ray, and gravitational lensing maps, as part of the STAGES survey. We characterize galaxies with…

We investigate when and how the relations of galaxy morphology and star forming activity with clustercentric radius become evident in galaxy clusters. We identify 162 galaxy clusters with total mass $M_{\rm tot}^{\rm cl} > 5 \times 10^{13}…

I present optical observations of the Blue Compact Dwarf Galaxy UM 462. The images of this galaxy show several bright compact sources. A careful study of these sources has revealed their nature of young Super Star Clusters. The ages…

Based on our compiled catalogue of fundamental astrophysical parameters for 593 open clusters, we analyze the relations between the chemical composition, spatial positions, Galactic orbital elements, age, and other physical parameters of…

To trace how dust-obscured star formation varies with environment, we compare the fraction of 24 micron sources in a super galaxy group to the field and a rich galaxy cluster at z~0.35. We draw on multi-wavelength observations that combine…

Star clusters are ideal tracers of star formation activity in systems outside the volume that can be studied using individual, resolved stars. These unresolved clusters span orders of magnitude in brightness and mass, and their formation is…

We present accurate relative ages for a sample of 55 Galactic globular clusters. The ages have been obtained by measuring the difference between the horizontal branch and the turnoff in two, internally photometrically homogeneous databases.…