We present a preliminary study of the star formation distribution within three Virgo Cluster galaxies using the 24 μm Spitzer observations from the Spitzer Survey of Virgo (SPITSOV) in combination with Hα observations. The purpose of our study is to explore the relationship between the star formation distribution within galaxies and the type (and phase) of interactions experienced within the cl...

We describe a particular aspect of the effects of the parent cluster tidal field (CTF) on stellar orbits inside cluster Elliptical galaxies (Es). In particular we discuss, with the aid of a simple numerical model, the possibility that collisionless stellar evaporation from elliptical galaxies is an effective mechanism for the production of the recently discovered intracluster stellar population...

We present a new wide-field map of the radio galaxy 3C 129 and its companion galaxy 3C 129.1 at λ = 90 cm. We see a distinct steep-spectrum feature near the head of 3C 129, extending in a direction perpendicular to the radio tails. We propose that this Crosspiece might consist of fossil radio plasma, which has been re-energized by the compression of the bow shock of the supersonically moving ga...

ASTRONOMY AND ASTROPHYSICS 1.2.2008 " The globular cluster distributions in the Galaxy, M31 and M87: are many globulars disappeared to the galactic centres? " Abstract. The radial distribution of globular clusters in our Galaxy, M31 and M87 is studied and compared with that of halo stars. The globular cluster distributions seem significantly flatter than those of the stars bulge. Assuming this ...

In this letter, we present the results of our study of galaxy-galaxy lensing in massive cluster-lenses spanning z = 0.17 to 0.58, utilizing high-quality archival Hubble Space Telescope (HST ) data. Local anisotropies in the shear maps are assumed to arise from dark matter substructure within these clusters. Associating the substructure with bright early-type cluster galaxies, we quantify the pr...

A key issue of the star formation process is its independence from the environmental conditions. In particular, it is not clear whether star formation in the outer Galaxy occurs in the same way as in the inner Galaxy. We present preliminary results of the analysis of a ∼ 440Ks ACISChandra observation of NGC1893, a young cluster (∼ 3−4Myrs), far away from the Galactic Center with the aim to stud...

We consider a sample of about 50 distant galaxy clusters at z > 0.15 (< 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 clu...

Galaxy clusters furnish extremely rich information on the contents and structure of our universe. The potential of galaxy cluster studies to constrain dark energy, for example, motivates a number of ambitious cluster surveys. Among these, surveys based on the Sunyaev-Zel'dovich (SZ) effect are particularly powerful for their ability to cleanly select clusters out to redshifts z > 1. Now poised ...