Three stars sit on the main sequence: a red dwarf of
PHYSICS · Subjective · Fermi University Physics · Astrophysics & Cosmology · Stellar structure, energy generation and evolution · Stellar structure, energy generation and evolution
Stars from the Inside, Ch Energy transport and the complete stellar model
Problem
Three stars sit on the main sequence: a red dwarf of 0.25M⊙, the Sun (1.0M⊙), and a hot, massive star of 15M⊙. For each star, predict whether its core is convective, whether its envelope is convective, or both, and justify each prediction from two facts: how large the opacity is through each star (H-minus and Kramers opacity where the gas is cool, electron scattering where it is hot), and how steeply the nuclear energy generation rate rises with temperature (much more steeply for the CNO cycle than for the proton-proton chain), which sets how large L(r)/m(r) stays near the centre.