Stellar Evolution and the Population Concept after 1950; The Vatican Conference

Extract

In the development of the concept of stellar populations the classification scheme adopted at the Vatican Conference of 1957 represents a major milestone. Thirteen years after Walter Baade's seminal papers, the conference reviewed progress in relevant fields of research and formulated a classification of population types that would remain the principal reference for the next decades. I shall review developments preceding the Conference, the initiatives that led to the Conference, the new scheme, and a few developments of later date.