Nucleosynthesis

Nucleosynthesis is the process of creating new atomic nuclei from preexisting nucleons (protons and neutrons). The primordial nucleons themselves were formed from the quark-gluon plasma of the Big Bang as it cooled below ten million degrees. A few minutes afterward, starting with only protons and neutrons, nuclei up to lithium (mass number 7) were formed. This first process of primordial nucleosynthesis may also be called nucleogenesis. The subsequent nucleosynthesis of the elements (including all carbon, all oxygen, etc.) occurs primarily in stars either by nuclear fusion or nuclear fission.
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Noun
1. (astronomy) the cosmic synthesis of atoms more complex than the hydrogen atom
(hypernym) synthesis
(classification) astronomy, uranology

The process by which the chemical elements are built by naturally occurring nuclear reactions. Nucleosynthesis took place when the universe was between one and five minutes old. It now takes place in the centre of stars and during supernova explosions. It can also take place in high energy collisions between existing atomic nuclei and high energy elementary particles such as those found in cosmic rays.