Inside massive stars, light atomic nuclei fuse to form heavier elements through nuclear fusion. The process starts with hydrogen burning into helium and proceeds through successive stages that create carbon, neon, oxygen, and finally iron. Each fusion step releases energy, which counteracts the star’s gravitational pull and keeps it stable.
When a star develops an iron core, fusion can no longer produce energy. The core collapses in a matter of seconds, triggering a supernova explosion. This violent event ejects the newly forged heavy elements at high speed into the surrounding interstellar space. Supernovae are therefore the primary source of many elements essential to life, such as iron in our blood and calcium in our bones.
Astronomers study these phenomena using spectroscopy on ground‑based and space‑based telescopes. By analysing the light emitted from supernova remnants and young star clusters, they can identify the chemical fingerprints of the expelled elements. Instruments like the Very Large Telescope and the James Webb Space Telescope provide increasingly detailed observations of these processes.
The results improve our understanding of the chemical evolution of the universe. They explain the observed abundances of elements in the Sun and ancient stars, and show how the material that forms planets and living organisms is continuously recycled through successive generations of stars.