UQ Media Release 2004 April 2

Astronomers discover dozens of mini-galaxies

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).

Media release and contact details
Contact: Dr Michael Drinkwater (07) 3365 3428 mjd@physics.uq.edu.au

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).

Online News Coverage

Download Images

NEW IMAGES FOR MINI GALAXIES STORY
- Low resolution cluster centre image
- Low resolution full-cluster image
- Caption: The central region of the Fornax Galaxy Cluster with the location of the new "mini-galaxies" indicated by the red squares.
- Credits:UQ Communications, Arna Karick (Uni. of Melbourne).
- For high resolution versions of these images please contact UQ photographic library coordinator Diana Lilley, d.lilley@uq.edu.au, +61 7 3365 2753.
- High resolution background image (tif 8Mb)
- Anglo-Australian Telescope (low resolution)
- Anglo-Australian Telescope (high resolution)
- Caption: The dome of the Anglo-Australian Telescope. Copyright Anglo-Australian Observatory, photo by David Malin.
Animation of how we think UCDs formed
- Small Animation file (windows, 9MB)
- Large Animation file (windows, 40MB)
- Credits: Dr. Kenji Bekki, University of New South Wales, Sydney
Discovery of a new type of galaxy (Previous release 2003 May)
- Previous Press Release and Images
- Low resolution (356x504 jpg 220kb)
- Medium resolution (1275x1805 jpg 360kb)
- High resolution (2550x3610 jpg 7.8Mb)
- Caption: The Fornax Cluster of galaxies with insets, 60-times magnified, of a normal dwarf galaxy (upper) and a newly-discovered "ultra-compact dwarf" (UCD) galaxy (lower). A simulation of the remains of a a normal dwarf galaxy after disruption to form a UCD is shown in the centre.
- Credits: UQ Communications. Insets: Hubble Space Telescope; background Michigan Curtis Schmidt Telescope and Arna Karick (University of Melbourne).
Images of Michael Drinkwater

Credits: UQ Communications/European Southern Observatory (background)

Telescopes used in this work

The galaxies were discovered with the 3.9-metre Anglo-Australian Telescope.
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)

Last modified: 2004 May 5; Created: 2003 May 22; Maintained by: Michael Drinkwater; Email: mjd @ physics uq edu au
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