\label{results} We calculated a grid of non-rotating stellar evolution sequences for initial masses between \(5{\,\mathrm{M}_\odot}\) and \(100{\,\mathrm{M}_\odot}\), at metallicities of \(Z\)=0.02, \(Z\)=0.008 and \(Z\)=0.004, roughly corresponding to the Galaxy, the LMC and the SMC, respectively. Additionally, we computed several models at lower metallicity. Since rapid rotation can change the properties of sub-surface convection \cite{Maeder2008}, we calculated a few rotating models to evaluate the effects of rotation on our results. These effects are discussed in Section \ref{rotation}.
Figures \ref{fig:20zsunsurf} and \ref{fig:60zsunsurf} show the evolution of the radial extent and location of the sub-surface convection zones in 20\({\,\mathrm{M}_\odot}\) and 60\({\,\mathrm{M}_\odot}\) models during the main sequence phase.