Summary: A new survey made with the Anglo-Australian Telescope (AAT) has revealed dozens of previously unsuspected miniature galaxies in the nearby Fornax galaxy cluster.
They belong to a class of galaxies dubbed "ultra-compact dwarfs" (UCDs), which was unknown before the same team of astronomers discovered 6 of them in the Fornax cluster in 2000. Now they say the UCDs outnumber the "conventional" elliptical and spiral galaxies in the central region of the Fornax cluster and they have found some in the Virgo galaxy cluster too. It is possible that at least some are left-over examples of the primordial `building blocks' that formed large galaxies by merging together. It is likely that they are very common but have been overlooked because they resemble nearby stars at first sight.
These results will be presented to the RAS National Astronomy Meeting at the Open University on Thursday 1 April (UK time) by Dr Steven Phillips of Bristol University. The research team is jointly lead by Dr Phillipps and Dr Michael Drinkwater (of the University of Queensland).
The central region of the Fornax Galaxy Cluster with the location of the new "mini-galaxies" indicated by the red squares. Credit: UQ Communications, Arna Karick (Uni. of Melbourne).
Credits: UQ Communications/European Southern Observatory (background)
The galaxies were discovered with the 3.9-metre
Other telescopes used previously were:
The Hubble Space Telescope (NASA)
The Very Large Telescope (European Southern Observatory)
The 2.5-meter (100-inch) Irénée du Pont telescope at Las Campanas Observatory (Carnegie Institution of Washington)