Supernova nucleosynthesis is a theory of the production of many different
chemical elements in
supernova explosions, first advanced by
Fred Hoyle in 1954. The
nucleosynthesis, or fusion of lighter elements into heavier ones, occurs during explosive oxygen burning and silicon burning. Those fusion reactions create the elements
silicon,
sulfur,
chlorine,
argon,
sodium,
potassium,
calcium,
scandium,
titanium and
iron peak elements:
vanadium,
chromium,
manganese,
iron,
cobalt, and
nickel. These are called "primary elements", in that they can be fused from pure hydrogen and helium in massive stars. As a result of their ejection from supernovae, their abundances increase within the interstellar medium. Elements heavier than nickel are created primarily by a rapid capture of
neutrons in a process called the
r-process. However, these are much less abundant than the primary chemical elements. Other processes thought to be responsible for some of the
nucleosynthesis of underabundant heavy elements, notably a
proton capture process known as the
rp-process and a
photodisintegration process known as the
gamma (or p) process. The latter synthesizes the lightest, most neutron-poor, isotopes of the heavy elements.