Family Traits of Galaxies: From the Tuning Fork to a Physical Classification in a Multi-Wavelength Context
Résumé
At the time of the Great Debate nebulæ were 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 (Sandage2005 ). 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 (Reynolds 1920 ).