Analysis of the data

One of the goals of this investigation is to find systematic differences between dwarf galaxies in clusters and in the field, i.e. between dwarf galaxies in high-density and-low density environments. The fact that the environment influences the formation and evolution of galaxies is well known, as can be illustrated by the density-morphology¹⁰ relations obeyed by galaxy populations, including dwarf galaxies,e.g. dEs in the field (outside clusters) are almost exclusively companions of giant galaxies, or else they are cluster members, whereas dwarf irregulars are little clustered. The cluster environment influences galaxies through numerous processes, like gravitational harassment, ram pressure stripping by the intra-cluster medium (ICM), confinement of the interstellar medium (ISM) by the ICM, tidal triggering of star formation, production of tidal dwarfs, tidal heating or truncation, etc. These processes may drive morphological transformations of dwarf galaxies, leading to the different populations of dwarf galaxies seen in the field and in clusters. But even for a given type of dwarf there may be structural differences between cluster and field dwarfs.

For the sake of these studies a sample of galaxy data from the literature comprising around 600 galaxies from the Virgo, Centaurus and Fornax clusters, as well as around group&fieldgalaxies from the Sculptor and Centaurus groups were added to the parameters from the galaxies in our sample. The estimated completeness range of our total sample is 45#45.

The parameters considered in the analysis were effective surface brightness, effective radius as well as the central surface brightness and scale length of the exp. profile.