Approximately what core temperature must a protostar reach to ignite sustained nuclear fusion?
Answer
10 million Kelvin
The definitive event marking the transition from a protostar to a true star is the ignition of sustained nuclear fusion in its core. This monumental physical change requires overcoming the strong electrical repulsion between positively charged hydrogen nuclei (protons). To achieve this, the core must be compressed to an extreme degree, forcing the temperature to reach approximately 10 million Kelvin (equivalent to about 18 million degrees Fahrenheit). At this specific temperature and corresponding immense pressure, four hydrogen nuclei can successfully fuse together to form a single helium nucleus, releasing the vast amounts of energy that define a luminous star.
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