First Heavy Elements: Birth of Stellar Nucleosynthesis

Approximately 13 billion years ago, the first generation of massive stars (Population III stars) began creating elements heavier than hydrogen and helium through nuclear fusion. These primordial stars, containing only the elements formed during Big Bang Nucleosynthesis, were significantly more massive than today's stars. As they exhausted their hydrogen fuel, their cores reached temperatures high enough to fuse helium into carbon, oxygen, and eventually heavier elements up to iron. When these stars ended their brief lives in supernovae explosions, they scattered these newly formed elements into space, enriching the interstellar medium and forever changing the chemical composition of the universe.