<P> 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 processes . 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 are thought to be responsible for some nucleosynthesis of other such heavy elements, notably, the 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 . </P> <P> A supernova is a massive explosion of a star that occurs under two principal scenarios . The first is that a white dwarf star undergoes a nuclear - based explosion after it reaches its Chandrasekhar limit after absorbing mass from a neighboring star (usually a red giant). The second, and more common, cause is when a massive star, usually a supergiant, reaches nickel - 56 in its nuclear fusion (or burning) processes . This isotope undergoes radioactive decay into iron - 56, which has one of the highest binding energies of all of the isotopes, and is the last element that produces a net release of energy by nuclear fusion, exothermically . </P>

How does a supernova produce elements heavier than iron