Family Traits of Galaxies: From the Tuning Fork to a Physical Classification in a Multi-Wavelength Context

Abstract

At the time of the Great Debate SubjectsGreat Debate nebulæ where recognized to have different morphologies and first classifications, sometimes only descriptive, have been attempted. A review of these early classification systems are well documented by the Allan Sandage’s review in 2005 (Sandage 2005). NamesSandage Allan This review emphasized the debt, in term of continuity of forms of spiral galaxies, due by the Hubble’s classification scheme to the Reynold’s systems proposed in 1920 (Reynolds1920). NamesReynolds John Henry