Related papers: Ultra-Compact Dwarf Candidates Near the Lensing Ga…

Photometric surveys of galaxy clusters have revealed a large number of ultra compact dwarfs (UCDs) around predominantly massive elliptical galaxies. Their origin is still debated as some UCDs are considered to be the remnant nuclei of…

Ultra-diffuse galaxies (UDGs) are objects which have very extended morphology and faint central surface brightness. Most UDGs are discovered in galaxy clusters and groups, but also some are found in low density environments. The diffuse…

Aim: To extend the investigations of ultra-compact dwarf galaxies (UCDs) beyond the well studied Fornax and Virgo clusters. Methods: We measured spectroscopic redshifts of about 400 compact object candidates with 19.2 < V < 22.4 mag in the…

We have discovered nine ultra-compact dwarf galaxies (UCDs) in the Virgo Cluster, extending samples of these objects outside the Fornax Cluster. Using the 2dF multi-fiber spectrograph on the Anglo-Australian Telescope, the new Virgo members…

We present a detailed analysis of two-band HST/ACS imaging of 21 ultra-compact dwarf (UCD) galaxies in the Virgo and Fornax Clusters. The aim of this work is to test two formation hypotheses for UCDs--whether they are bright globular…

We have discovered strong gravitational lensing by the galaxy ESO325-G004, in images obtained with the Advanced Camera for Surveys on the Hubble Space Telescope. The lens galaxy is a boxy group-dominant elliptical at z=0.0345, making this…

We present multi-wavelength imaging and analysis of a low surface brightness (LSB) dwarf galaxy in the Extended Chandra Deep Field South (ECDFS), SMDG0333094-280938, with particular emphasis on data from the Euclid space telescope and from…

Context. Ultra-compact dwarfs (UCDs) are stellar systems displaying colours and metallicities between those of globular clusters (GCs) and early-type dwarf galaxies, as well as sizes of Reff <= 100 pc and luminosities in the range -13.5 <…

We used V and I CCD photometry to search for low-surface brightness dwarf galaxies (LSBD) in the central (<0.5 h^-1 Mpc) region of the groups NGC 6868, NGC 5846, HCG 42 and the poor cluster IC 4765. Using the parameters given by the…

NGC 3311, the giant cD galaxy in the Hydra cluster (A1060), has one of the largest globular cluster systems known. We describe new Gemini GMOS (g',i') photometry of the NGC 3311 field which reveals that the red, metal-rich side of its…

We present a photometric search for UCD candidates in the nearby galaxy group NGC 1023 (d=11 Mpc) -- the poorest environment searched for UCDs yet --, based on wide field imaging with CFHT. After photometric and morphological selection, we…

We recently initiated a search for ultra-compact dwarf galaxies (UCDs) in the Centaurus galaxy cluster (Mieske et al. 2007), resulting in the discovery of 27 compact objects with -12.2<M_V<-10.9 mag. Our overall survey completeness was…

Ultra-compact dwarf galaxies (UCDs) are a new type of galaxy we have discovered in the central region of the Fornax and Virgo clusters. Unresolved in ground-based imaging, UCDs have spectra typical of old stellar systems. Ninety-two have…

The HST ACS Coma Cluster Treasury Survey is a deep two passband imaging survey of the nearest very rich cluster of galaxies, covering a range of galaxy density environments. The imaging is complemented by a recent wide field redshift survey…

Recent observations have highlighted a significant population of faint but large (r_eff>1.5 kpc) galaxies in the Coma cluster. The origin of these Ultra Diffuse Galaxies (UDGs) remains puzzling, as the interpretation of the observational…

We present the results of the first search for Ultra Compact Dwarfs (UCDs) in the Perseus Cluster core, including the region of the cluster around the unusual Brightest Cluster Galaxy (BCG) NGC 1275. Utilising Hubble Space Telescope…

We present a detection of 89 candidates of ultra-diffuse galaxies (UDGs) in a 4.9 degree$^2$ field centered on the Hickson Compact Group 95 (HCG 95) using deep $g$- and $r$-band images taken with the Chinese Near Object Survey Telescope.…

We have identified a previously unrecognized population of very compact, embedded low-mass Galactic stellar clusters. These tight (r$ \approx $0.14 pc) groupings appear as bright singular objects at the few arcsec resolution of the Spitzer…

We report the discovery of a massive ultra-compact quiescent galaxy that has been strongly-lensed into multiple images by a foreground galaxy at z = 0.960. This system was serendipitously discovered as a set of extremely Ks-bright…

We report the discovery of an Ultra Compact Dwarf (UCD) associated with the Sombrero galaxy (M104). This is the closest massive UCD known and the first spectroscopically verified massive UCD which is located in a low density environment.…