nucleosynthesis

Nucleosynthesis is the creation of atomic nuclei, i.e., the creation of elements. Types include:

• Big Bang nucleosynthesis - formation of hydrogen and helium in the early universe, very soon after the Big Bang.
• Stellar nucleosynthesis (see below).
• Supernova nucleosynthesis - processes within supernovae such as the r-process (rapid neutron capture), rp-process (type of proton capture), and the alpha process.
• Cosmic ray spallation - reduction of nuclei through impact with cosmic rays.
• Radioactivity.

Stellar nucleosynthesis includes the processes:

• proton-proton chain.
• CNO cycle.
• triple alpha process.
• s-process (slow neutron capture).
• r-process.
• photodisintegration (nucleus chipped away by gamma rays).
• carbon burning (if 6×10⁸ K, producing oxygen, neon, sodium, and magnesium).
• oxygen burning (if 10⁹ K, producing magnesium, silicon, phosphorus, and sulfur).
• neon burning (producing magnesium).
• silicon burning (latter alpha process steps).