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dEs are frequently denoted as examples of “stellar fossile” systems in which the bulk of their SF occurred in the past. They are preferentially located in morphologically evolved environments [@tre02], i.e. in regions with high galaxy densities and dominate the morphological types of galaxies in clusters, as e.g. Virgo, Coma, Fornax, and Perseus. Furthermore, dEs cluster strongly around luminous elliptical/S0 galaxies [@tul08]. The evolution of this galaxy type should be mainly caused by gas and tidal effects on SF and structure and indicates that it is strongly affected by environment.

Already [@bot85] found that cluster dEs are usually almost free of interstellar gas and contain few young stars. In trying to understand the dE population, structural regularities and correlations must be studied, as it is known since the 80th, between optical surface brightness and luminosity [@kor85; @fer94] and between luminosity and stellar velocity dispersion which also correlates with metallicity (e.g. [@pet93]). Boselli et al. [@bos08b] proposed to understand these ”Kormendy” relations by processes having transformed dIrrs after their cluster infall, but accuse the still existing lack of numerical simulations of such transformation.

Furthermore, dEs often have flattened profiles but are mostly kinematically supported by their stellar velocity dispersion rather 