  A recent all-object spectroscopic survey centred on the Fornax cluster of
galaxies, has discovered a population of sub-luminous and extremely compact
members, called ``ultra-compact dwarf'' (UCD) galaxies. In order to clarify the
origin of these objects, we have used self-consistent numerical simulations to
study the dynamical evolution a nucleated dwarf galaxy would undergo if
orbiting the center of the Fornax cluster and suffering from its strong tidal
gravitational field. We find that the outer stellar components of a nucleated
dwarf are removed by the strong tidal field of the cluster, whereas the nucleus
manages to survive as a result of its initially compact nature. The developed
naked nucleus is found to have physical properties (e.g., size and mass)
similar to those observed for UCDs. We also find that although this formation
process does not have a strong dependence on the initial total luminosity of
the nucleated dwarf, it does depend on the radial density profile of the dark
halo in the sense that UCDs are less likely to be formed from dwarfs embedded
in dark matter halos with central `cuspy' density profiles. Our simulations
also suggest that very massive and compact stellar systems can be rapidly and
efficiently formed in the central regions of dwarfs through the merging of
smaller star clusters. We provide some theoretical predictions on the total
number and radial number density profile of UCDs in a cluster and their
dependences on cluster masses.
