The nuclear reaction thought to occur in the Sun is called the proton-proton cycle.
The reaction chain between protons that ultimately leads to helium is the proton-proton cycle.
Chains of thermonuclear reactions, such as the proton-proton cycle and the carbon cycle, account for the energy radiated from the Sun and most other stars.
Proton-proton cycle, also called Proton-proton Reaction, chain of thermonuclear reactions that is the chief source of the energy radiated by the Sun and other cool main-sequence stars.
The faint red dwarfs use the proton-proton cycle exclusively, whereas stars such as the Sun shine mostly by the proton-proton reaction but derive some contribution from the carbon cycle as well.
In a proton-proton cycle, four hydrogen nuclei (protons) are combined to form one helium nucleus; 0.7 percent of the original mass is lost mainly by conversion into heat energy, but some energy escapes in the form of neutrinos.
A small fraction of the hydrogen nuclei possess sufficiently high speeds that, on colliding, their electrostatic repulsion is overcome, resulting in the formation, by means of a set of fusion reactions, of helium nuclei and a release of energy (see proton-proton cycle).
As a result, water and fat protons cycle in and out of phase with respect to one another.
