Internal Constitution of the Stars

Arthur Eddington's work, particularly his book The Internal Constitution of the Stars (1925), was foundational in understanding the inner workings of stars. He investigated stellar structure, including temperature, density, and pressure gradients, and how these change over time as hydrogen converts to helium. Eddington also proposed the proton-proton reaction as a source of stellar energy, linking it to Einstein's mass-energy equivalence ((E=mc^2)). His research led to the theoretical concept of the Eddington mass limit, an upper bound on a star's mass where radiation pressure balances gravity, explaining why extremely massive stars are not observed.1234