A Survey for Fine Structure in E+SO Galaxies

Abstract

The authors present the results of an imaging survey aimed at finding and cataloguing various kinds of fine structure in 74 nearby E + SO galaxies. More than half of the objects feature at least one of the following: ripples ("shells"), strongly boxy isophotes, X-structure, and plumes, thus suggesting a multi-component origin (mergers, accretions) for these galaxies. The presence of fine structure correlates with spectral line strengths measured by Faber et al. (1990): ellipticals with ripples, plumes, etc., tend to have stronger-than-average Hβ lines and weaker-than-average CN and Mg2 indices for their luminosity, suggesting that - compared to their featureless counterparts - they may have experienced more recent star formation.