Galaxy threshing and ultra-compact dwarfs in the Fornax Cluster

MD Gregg*, MJ Drinkwater, MJ Hilker, S Phillipps, JB Jones, HC Ferguson

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

5 Citations (Scopus)


We have discovered a new type of galaxy in the Fornax Cluster: 'ultra-compact' dwarfs (UCDs). The UCDs are unresolved in ground-based imaging and have spectra typical of old stellar systems. Although the UCDs resemble overgrown globular clusters, based on VLT UVES echelle spectroscopy, they appear to be dynamically distinct systems with higher internal velocity dispersions and M/L ratios for a given luminosity than Milky Way or M31 globulars. Our preferred explanation for their origin is that they are the remnant nuclei of dwarf elliptical galaxies which have been tidally stripped, or 'threshed' by repeated encounters with the central cluster galaxy, NGC1399. If correct, then tidal stripping of nucleated dwarfs to form UCDs may, over a Hubble time, be an important source of the plentiful globular cluster population in the halo of NGC1399, and, by implication, other cD galaxies. In this picture, the dwarf elliptical halo contents, up to 99% of the original dwarf luminosity, contribute a significant fraction of the populations of intergalactic stars, globulars, and gas in galaxy clusters.

Original languageEnglish
Pages (from-to)113-117
Number of pages5
JournalAstrophysics and Space Science
Issue number1
Publication statusPublished - 2003
EventJoint European and National Astronomical Meeting (JENAM 2002) - OPORTO, Portugal
Duration: 2 Sept 20027 Sept 2002

Bibliographical note

Publisher: Kluwer Academic
Name and Venue of Conference: JENAM 2002. September 2003, Oporto


  • galaxies
  • interactions
  • clusters


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