Eli5: How are scientists able to determine the lifetime of the sun and other stars? Are the reactions that happen within stars reproducible in a lab?
In: Physics
Observing and comparing diffrent stars let us understand the processes in them which make them emitting light and based on the light you could measure in which phase a star is.
This allows us to understand if a star is young, adult or close to the end of its lifetime – all three of course on a cosmic scale
The basic reaction inside a star is nuclear fusion a relatively simple principle that science now understands fairly well. In order for stars to start fusing matter together (starting with hydrogen) you need a great deal of mass, the more mass you have the quicker the reactions happen, so somewhat opposite to what some people might think the larger the star the more potential fuel it has, but also the quicker it “burns” through the fuel, so very large stars only burn for a few million years whereas smaller stars like our Sun last for billions of years.
What happens during the life of a large star. Part 1: Early life of a star – https://youtu.be/vVE0B6g9F_0
What happens during the life of a large star. Part 2: Star collapse and going Supernova – https://youtu.be/w1GlDVt1Mpk
What happens during the life of a large star. Part 3: Neutron stars, Pulsars and Magnetars – https://youtu.be/Yyz8bdZqQ4Q
In physics you have what called degeneration, meaning that the matter contained in the sun is always reacting (hence the nuclear reactions you might have heard about; the sun is a bid nuclear reactor) so the matter that’s composing it consumed. But this matter is not infinite.
Knowing the mass of the sun and its composition, you can calculate it’s remaining lifetime.
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