Lakhasly

About 99% of the energy output of the sun comes from the various p-p chains, with the other 1% coming from the CNO cycle.According to one model of the sun, 83.3 percent of the 4He produced by the various p-p branches is produced via branch I while p-p II produces 16.68 percent and p-p III 0.02 percent.The difference is apparently due to slightly different assumptions about the composition and metallicity of the sun.

About 99% of the energy output of the sun comes from the various p–p chains, with the other 1% coming from the CNO cycle. According to one model of the sun, 83.3 percent of the 4He produced by the various p–p branches is produced via branch I while p–p II produces 16.68 percent and p–p III 0.02 percent. Since half the neutrinos produced in branches II and III are produced in the first step (synthesis of a deuteron), only about 8.35 percent of neutrinos come from the later steps (see below), and about 91.65 percent are from deuteron synthesis. However, another solar model from around the same time gives only 7.14 percent of neutrinos from the later steps and 92.86 percent from the synthesis of deuterium nuclei. The difference is apparently due to slightly different assumptions about the composition and metallicity of the sun.