Labels:text | screenshot OCR: NUCLEAR FUSION STARS SHINE by a process of nuclear Deuterium Positron Helium-4 fusion. For fusion to occur, a star's nucleus nucleus core temperature must be at least 10 million ℃ (18 million "F). Under these conditions, protons (hydrogen Proton nuclei) fuse to form helium nuclei. Neutrino In the process, 0.7 percent of the mass of the hydrogen is converted to energy. In low-mass stars, such as the Sun, the process of fusion is fairly simple and is known as the Gamma-ray Helium-3 nucleus photon proton-proton chain. More massive PROTON-PROTON CHAIN stars form progressively heavier Protons collide and fuse together to form elements in more complex fusion more complex helium atoms. In the reactions as they reach old age. process, they release energetic particles such as neutrinos, positrons, ...