Origin of the Structure Difference Between Elliptical Galaxies and Dwarf Elliptical Galaxies

Abstract

According to the observations of nearby elliptical galaxies, there is a clear distinction in structural and chemical quantities between dwarf ellipticals and normal ellipticals in spite of their morphological similarity. The central concentration of dwarf ellipticals is relatively low and their luminosity profiles are best fitted by an exponential function, whereas the profiles of normal ellipticals are known to follow de Vaucouleurs’ law (Faber & Lin 1983; Binggeli, Sandage & Tarenghi 1984; Ichikawa, Wakamatsu & Oka-mura 1986). Moreover, the color of many dwarf ellipticals becomes redder towards outer radii of the system (Vader et al. 1988; Kormendy & Djor-govski 1989), and this trend of color gradient is clearly opposite to normal galaxies. The origin of these striking features of dwarf ellipticals remains yet to be explained (for a review see Ferguson & Binggeli 1994). In particular, no attempts have ever been made to examine whether the supernova feedback mechanism is viable also in this context.