The cluster environment is the site of important transformations in galaxies at a relatively recent cosmological epoch: the galactic morphological types and star formation activity have evolved significantly during the last few Gyrs. How is this related to the galactic gas content? The first part of this paper briefly presents the optical observations of galaxies in distant clusters, while the ...

The currently available empirical evidence on the star formation processes in the extreme, high-pressure environments induced by galaxy encounters, mostly based on high-resolution Hubble Space Telescope imaging observations, strongly suggests that star cluster formation is an important and perhaps even the dominant mode of star formation in the starburst events associated with galaxy interactio...

We have obtained high-dispersion spectra for four massive star clusters in the dwarf irregular galaxies NGC 4214 and NGC 4449, using the HIRES spectrograph on the Keck I telescope. Combining the velocity dispersions of the clusters with structural parameters and photometry from images taken with the Hubble Space Telescope, we estimate mass-to-light ratios and compare these with simple stellar p...

We have obtained high-dispersion spectra for four massive star clusters in the dwarf irregular galaxies NGC 4214 and NGC 4449, using the HIRES spectrograph on the Keck I telescope. Combining the velocity dispersions of the clusters with structural parameters and photometry from images taken with the Hubble Space Telescope, we estimate mass-to-light ratios and compare these with simple stellar p...

We present age measurements for 195 star clusters in the Small Magellanic Cloud based on comparison of integrated colors measured from the Magellanic Clouds Photometric Survey with models of simple stellar populations. We find that the modeled nonuniform changes of cluster colors with age can lead to spurious age peaks in the cluster age distribution, that the observed numbers of clusters with ...

Following the discovery of a black hole (BH) with a mass of 10–10 M in a starburst galaxy M82, we study formation of such a BH via successive merging of stellar-mass BHs within a star cluster. The merging has a runaway characteristic. This is because massive BHs sink into the cluster core and have a high number density, and because the merging probability is higher for more massive BHs. We use ...

The observed morphological evolution since z ∼ 0.5 within galaxy clusters provides evidence for a hierarchical universe. This evolution is driven by dynamical effects that operate within the cluster environment – suppression of star-formation by ram-pressure and viscous stripping of the intra-galactic medium and tidal heating of disks by grav-itational encounters. 1. Evidence for a hierarchical...

Star clusters are found in ∼40% of the Local Group galaxies. Their properties are reviewed. The impact of galaxy environment on the evolution and survival of star clusters is discussed. Possible evidence for cluster formation triggered by galaxy interactions, gradients in cluster size, metallicity and stellar content with galactocentric radius and variations as a function of galaxy type are bri...

We measure the clustocentric distances of 52,569 galaxies in the redshift range of 0.015 < z < 0.068. By “clustocentric distance” we mean the transverse projected distance to the center of the nearest cluster within ±2000 km s. By “cluster” we mean a bound group of at least Ngal galaxies brighter than Mr = −19 mag; we consider different “richness” criteria of Ngal = 5, 10, and 20. We examine th...

We analyse new SCUBA-2 submillimeter and archival SPIRE far-infrared imaging of a z =1.62 cluster, Cl 0218.3−0510, which lies in the UKIDSS/UDS field of the SCUBA-2 Cosmology Legacy Survey. Combining these tracers of obscured star formation activity with the extensive photometric and spectroscopic information available for this field, we identify 31 far-infrared/submillimeter-detected probable ...