Solar nuclear fusion reaction: hydrogen

Never mind. In the center of the Sun is the core, the Sun s power plant in which nuclear fusion reactions turn hydrogen into helium and generate tremendous amounts of heat. Here, the gas density is more than 100 times that of water, or 14 times that of lead. In fact, the core contains 40 percent of the solar mass. 2 Sir, at that density, why isn t the core a solid ... 

Solar fusion Nuclear fusion reactions are responsible for the glow and heat from stars such as the Sun. The temperature of the Sun s core Is about 15,000,000 K. It is so hot and dense that hydrogen nuclei fuse to produce helium. After billions of years, the Sun s hydrogen will be mostly depleted. Its temperature will rise to about 100,000,000 K, and the fusion process will then change helium into carbon. 

On solar scales, the change is slow. It takes a billion years for only 0.01 percent of the Sun s mass to metamorphose into beautiful sunshine. The Sun s nuclear reactions are slowed because the positively charged protons repel each other. This repulsion slows down the fusion. If the rate were much quicker, the Sun would explode like a big hydrogen bomb. 

It is clear, for example from radio-carbon dating of rocks in the earth s surface, that the solar system must be very much older than the Kelvin age of 3 x 107 years. It is now taken for granted that the main source of stellar energy comes from nuclear reactions. The fusion of four protons (hydrogen nuclei) to an alpha-particle (helium nucleus) is associated with the release of energy Q, where Q k, 26 MeV. The total available energy is thus... 

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