Monday, March 17, 2008
After a star exhausts its Hydrogen fuel, it either stops shining, or if it is massive enough, continues on to heavier elements. A red giant star, beyond its Hydrogen rations begins to fuse Helium. Helium, through the triple alpha process (a process where two Helium atoms fuse to form Beryllium, and then another alpha particle joins, forming Carbon) can produce Carbon, which produces Neon, Oxygen, Silicon, Nickel, and as alpha particles (note 3) are added to these heavier elements, forming Nickel, and finally iron. If a star reaches an iron core it explodes in a supernova, explained here. Only massive stars can obtain iron cores, with temperatures in the center soaring to 90 trillion degrees.