Fred Hoyle, Red Giants and beyond

Abstract

The impact of Fred Hoyle’s work on the structure and evolution of red giants, particularly his breakthrough contribution with Martin Schwarzschild (1955), is described and assessed. Working with his students in the early 1960s, Hoyle presented new physical ways of understanding some of the approximations used, and results obtained, in that seminal paper. His initial viewpoint on the critical role of the outer surface boundary condition was replaced by a more subtle, if related one, which emphasized the peculiar difficulty of storing much mass outside a dense stellar core. That viewpoint that — low-mass red giants are essentially white dwarfs with a serious mass-storage problem — is still extremely fruitful.