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Week 7: Variable stars

Completion requirements

Diagram depicting the three-alpha process, in which three Helium nuclei fuse to form a Carbon nucleus. To the left, two Helium nuclei, each consisting of a two blue neutrons and two red protons, fuse together to form a Beryllium nucleus (labelled as unstable). A third Helium nucleus is then added, forming a Carbon nucleus on the right, consisting of six neutrons and six protons. Yellow flashes at each stage indicate energy released as the nuclei fuse together.

 1.1 Helium as a nuclear fuel