Stars shine for millions and billions of years. This is sustained by ongoing fusion of hydrogen and other elements in the core region of each star. Every time four hydrogen atoms fuse through a series of steps into a helium nucleus, a tiny bit of energy is released. Eventually, once iron has been produced in the core, fusion is no longer possible. The star cannot produce any more energy and thus has to explode as a gigantic supernova.
Associated Book Chapters from Searching for the Oldest Stars: Ancient Relics from the Early Universe
- Chapter 3: Stars, Stars, More Stars
- Chapter 4: Stellar Evolution—From Birth to Death
- Chapter 6: Welcome to Our Milky Way
