<P> (12 C + 1 H → 13 N + γ then 13 N → 13 C + e + + ν then 13 C + 1 H → 14 N + γ then 14 N + 1 H → 15 O + γ then 15 O → 15 N + e + + ν then 15 N + 1 H → 12 C + 4 H e + γ (\ displaystyle \ left \ ((\ begin (aligned) && () ^ (12) \! C+ () ^ (1) \! H& \ rightarrow () ^ (13) \! N+ \ gamma \ \ (\ text (then)) && () ^ (13) \! N& \ rightarrow () ^ (13) \! C + e ^ (+) + \ nu \ \ (\ text (then)) && () ^ (13) \! C+ () ^ (1) \! H& \ rightarrow () ^ (14) \! N+ \ gamma \ \ (\ text (then)) && () ^ (14) \! N+ () ^ (1) \! H& \ rightarrow () ^ (15) \! O+ \ gamma \ \ (\ text (then)) && () ^ (15) \! O& \ rightarrow () ^ (15) \! N + e ^ (+) + \ nu \ \ (\ text (then)) && () ^ (15) \! N+ () ^ (1) \! H& \ rightarrow () ^ (12) \! C+ () ^ (4) \! He+ \ gamma \ \ \ end (aligned)) \ right .) </P> <P> This process can be further understood by the picture on the right, starting from the top in clockwise direction . </P> <P> The rate of nuclear fusion depends strongly on density . Therefore, the fusion rate in the core is in a self - correcting equilibrium: a slightly higher rate of fusion would cause the core to heat up more and expand slightly against the weight of the outer layers . This would reduce the fusion rate and correct the perturbation; and a slightly lower rate would cause the core to cool and shrink slightly, increasing the fusion rate and again reverting it to its present level . </P> <P> However the Sun gradually becomes hotter during its time on the main sequence, because the helium atoms in the core are denser than the hydrogen atoms they were fused from . This increases the gravitational pressure on the core which is resisted by a gradual increase in the rate at which fusion occurs . This process speeds up over time as the core gradually becomes denser . It is estimated that the sun has become 30% brighter in the last four and a half billion years and will continue to increase in brightness by 1% every 100 million years . </P>

A gamma ray is produced in the core of the sun. what happens after that