The Formation and Evolution of Galaxies: Perspectives on the Origin of the Hubble Sequence

Abstract

Abstract. I review recent observational progress concerning the evolution of the morphological distribution of galaxies in the rich cluster environment and in the faint field population. By coupling HST imagery with ground-based spectroscopic diagnostics, evidence accumulates that galaxy morphology can be a transient phenomenon reflecting various changes in the star formation rate. Possible physical processes responsible for these changes are discussed. Future progress in understanding them will depend on securing 2-D spectroscopic data for representative systems. 1