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What makes the stars shine?
Stars produce their energy through nuclear fusion. For most stars, this process is dominated by a process called the "proton-proton chain," a sequence of events that transforms four hydrogen atoms into one helium atom. The proton-proton chain reaction fuels most stars and provides them with the energy required to support their enormous masses for most of their lifetimes; indeed, it is the source of our own Sun's power.

Larger stars, whose crushing weight generates even higher temperatures at their cores, utilize a more complex fusion process called the "CNO cycle." In this reaction, trace amounts of carbon, nitrogen, and oxygen serve as catalysts in fusing four hydrogen atoms into one helium. While this method yields more energy, the higher temperatures required can only be achieved by stars more massive than the Sun, and such stars are doomed by their prolific output to short lives.

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