The nucleosynthesis is a whole of process physical leading to the synthesis of atomic nuclei, by fission or nuclear Fusion.

There exist several astrophysical processes which would be responsible for the nucleosynthesis in the universe, the precursors being the Processus R, Processus S and Processus P.

The four basic types of nucleosynthesis are:

• the paramount Nucleosynthesis which took place during the first minutes of the universe, person in charge of the formation of the light cores, mainly Hélium 4 but also Deutérium, Lithium. No element larger than lithium was created during this nucleosynthesis.

• the stellar Nucléosynthèse takes place in the star S, and is divided into two processes:
• at the time of their existence, the stars create most of the elements between lithium and the Fer;
• during the explosion of massive stars, an explosive form of nucléosytnhèse takes place and produces the majority of the elements heavier than the Fer.
• the cosmic Spallation, or interstellar nucleosynthesis which produces light elements such as the Lithium and the Bore, by matter bombardment by cosmic rays.

The theories on the nucleosynthesis are tested by calculating abundances of the elements and their isotopes and while comparing with the measurements taken by the observation.

See too

• Hubert Reeves

• Jean Audouze