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The Sun
Noble Gases

Why doesn't helium in the sun's core undergo fusion?


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February 06, 2008 5:45AM

The proton-proton chain reaction that fuses hydrogen into helium begins at a threshold of about 10 million degrees Kelvin. The fusion of helium doesn't begin until a temperature of about 100 million degrees Kelvin is reached. All the hydrogen must be exhausted and then a star must undergo further collapse for the new, higher threshold temperature to be reached to cause the initiation of helium fusion. Shazam! Now that's hot! Use the link below to our friends at Wikipedia for details.