What critical temperature threshold ignites helium fusion into carbon and oxygen?
Answer
100 million Kelvin
After the Sun transitions out of the hydrogen-burning main sequence, the helium core contracts under gravity, causing its temperature and density to increase dramatically. This compression continues until a critical threshold temperature is achieved within the core. When the temperature reaches approximately 100 million Kelvin, the kinetic energy of the helium atoms is sufficient to overcome their mutual electrostatic repulsion, allowing them to fuse together. This fusion, known as the triple-alpha process, results in the formation of heavier elements, primarily carbon and oxygen.
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