Constraints on the Structure, Evolution, and Approach to Thermonuclear Runaway in Intermediate Mass and Massive Stars

This thesis provides an assessment of stellar evolution models for intermediate-mass and massive stars in advanced stages of evolution through a detailed cooperation between simulations and observations of nearby stars and eclipsing binary stars. We also make a detailed study of the approach to unstable helium burning, the core flash, and thermally pulsing phases. We formed the first detailed analysis of how such burning evolves from quasi-statics to explosive helium burning as a function of progenitor mass.