Red Giant or Supergiant

Red Giant or Supergiant - fusion occurs at about 1.2...

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Red Giant or Supergiant When the core fuel runs out again, the core resumes its collapse. If the star is massive enough, it will repeat stage 5. The number of times a star can cycle through stages 5 to 6 to 7 depends on the mass of the star. Each time through the cycle, the star creates new heavier elements in its core (stage 6) from the ash of fusion reactions in the previous cycle. This creation of heavier elements from lighter elements is called stellar nucleosynthesis . For the most massive stars, this continues up to the production of iron in the core. Stars like our Sun will synthesize elements only up to carbon and oxygen in their cores. Each repeat of stages 5 to 6 to 7 occurs over a shorter time period than the previous repeat. Carbon fusion occurs at about 600 million K, Neon
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Unformatted text preview: fusion occurs at about 1.2 billion K, Oxygen fusion occurs at about 1.5 billion K, and Silicon fusion occurs at about 2.7 billion K. Up to the production of iron in the most massive stars, the nuclear fusion process is able to create extra energy from the fusion of lighter nuclei. But the fusion of iron nuclei absorbs energy. The core of the massive stars implodes and the density gets so great that protons and electrons are combined to form neutrons + neutrinos and the outer layers are ejected in a huge supernova explosion. The more common low-mass stars will have a gentler death, forming a planetary nebula....
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