Evolution of T_C and ρ_C for classical models of 15, 20, and 30 M_⊙ at solar metallicity, and for the three nuclear rates’ references (colour-coded). The dotted coloured lines indicate the C-ignition and core C-exhaustion for each model. The dash-dotted grey line indicates the limit between ideal gas (left) and degenerate gas (right). The shaded grey area indicates the pair instability domain, e⁺e⁻.