Core properties at the end of core He burning as a function of initial mass. Panel (a): central density ρ_c and CO core mass M_CO at the end of core He burning, shown as a function of the initial He star mass $M_{\mathrm{He}}^{\mathrm{i}}$. Panel (b): corresponding central ${}^{12}\mathrm{C}$ mass fraction X_C at the end of core He burning, with the top axis indicating the CO core mass M_CO for each $M_{\mathrm{He}}^{\mathrm{i}}$. Light and dark gray shaded regions denote models undergoing radiative core C and Ne burning, respectively. The dotted and dashed lines represent the threshold ¹²C mass fractions separating convective and radiative burning regimes.