Distribution of heavy elements for a model with a dilute core. The three hashed areas correspond to the mass of the compact core (only made of heavy elements), the mass of heavy elements in the dilute core region excluding the area where Z < Z₁, and the mass of heavy elements in the rest of the envelope (where Z < Z₁). Z₁ is the mass fraction of heavy elements in the outer envelope. Z_dilute is the maximum mass fraction in the dilute core, m_dilute monitors the extent of the dilute core in terms of mass.