Although playing a key role in the understanding of the supernova phenomenon, the evolution of massive stars still suffers from uncertainties in their structure, even during their quiet main sequence phase and later on during their subgiant and heliu
m burning phases. What is the extent of the mixed central region? In the local mixing length theory (LMLT) frame, are there structural differences using Schwarzschild or Ledoux convection criterion? Where are located the convective zone boundaries? Are there intermediate convection zones during MS and post-MS phase, and what is their extent and location? We discuss these points and show how asteroseismology could bring some light on these questions.
Observations suggest that a relationship exists between the driving mechanism of roAp star pulsations and the heavy element distribution in these stars. We attempt to study the effects of local and global metallicity variations on the excitation mech
anism of high order p-modes in A star models. We developed stellar evolutionary models to describe magnetic A stars with different global metallicity or local metal accumulation profiles. These models were computed with CLES (Code Li`egeois devolution stellaire), and the stability of our models was assessed with the non-adiabatic oscillation code MAD. Our models reproduce the blue edge of the roAp star instability strip, but generate a red edge hotter than the observed one, regardless of metallicity. Surprisingly, we find that an increase in opacity inside the driving region can produce a lower amount of driving, which we refer to as the inverse $kappa$-mechanism.
