Density, temperature, and elemental abundance profiles for the 10 and 30 M_⊙ stars at the end of their evolution. The top panel shows temperature (T, solid lines) and density (ρ, dotted lines) for both models. The middle and bottom panels present the corresponding abundance profiles. The 10 M_⊙ star develops a degenerate O-Ne-Mg core, while the 30 M_⊙ model forms an iron core prior to collapse.