What structure develops in high-mass stars due to successive fusion cycles?

Onion-like structure with shells of different burning fuel

High-mass stars experience much greater gravitational compression, leading to significantly higher core temperatures and pressures than smaller stars. This allows them to fuse elements heavier than hydrogen early on. Once hydrogen is spent, the core contracts until conditions are right to fuse helium into carbon and oxygen. This process does not stop; it repeats with progressively heavier elements (like carbon into neon, neon into oxygen, and oxygen into silicon). Each stage occurs in a distinct shell surrounding the core, creating a distinct, layered arrangement described as an onion-like structure, with the heaviest element fusing closest to the center.