<Li> The Rp - process </Li> <Li> The P - process </Li> <P> Hydrogen fusion (nuclear fusion of four protons to form a helium - 4 nucleus) is the dominant process that generates energy in the cores of main - sequence stars . It is also called "hydrogen burning", which should not be confused with the chemical combustion of hydrogen in an oxidizing atmosphere . There are two predominant processes by which stellar hydrogen fusion occurs: proton - proton chain and the carbon - nitrogen - oxygen (CNO) cycle . Ninety percent of all stars, with the exception of white dwarfs, are fusing hydrogen by these two processes . </P> <P> In the cores of lower - mass main - sequence stars such as the Sun, the dominant energy production process is the proton--proton chain reaction . This creates a helium - 4 nucleus through a sequence of chain reactions that begin with the fusion of two protons to form a deuterium nucleus (one proton plus one neutron) along with an ejected positron and neutrino . In each complete fusion cycle, the proton--proton chain reaction releases about 26.2 MeV . The proton--proton chain reaction cycle is relatively insensitive to temperature; a 10% rise of temperature would increase energy production by this method by 46%, hence, this hydrogen fusion process can occur in up to a third of the star's radius and occupy half the star's mass . For stars above 35% of the Sun's mass, the energy flux toward the surface is sufficiently low and energy transfer from the core region remains by radiative heat transfer, rather than by convective heat transfer . As a result, there is little mixing of fresh hydrogen into the core or fusion products outward . </P>

Where does nuclear fusion occur in a star
find me the text answering this question