Numerical experiments to help understand cause and effect in massive star evolution

The evolution of massive stars is affected by a variety physical processes including convection, rotation, mass loss and binary interaction. Because these modify the internal chemical abundance profiles in multiple ways simultaneously, it can be challenging to determine which properties stellar interior are primarily driving overall evolution. Building on previous work, we develop new modelling approach called SNAPSHOT that allows us isolate key features profile drive stars. Using our approach, compute numerical structure models thermal equilibrium covering phases For main sequence, demonstrate with same very similar surface have different distributions hydrogen convective core masses. We discuss why expand after sequence fundamental reasons for they become red, blue or yellow supergiants. post-main small changes cause large effects properties. also produce supergiants loops. Our show lower metallicity tend more compact due combined effect CNO abundances burning regions opacity envelope.