2016年9月20日火曜日

12 Life of Stars

12 Life of StarsWhat is the Universe?】Dialogue with the Universe

Big star burns out faster than small one.
 Since stars have a limited supply of hydrogen in their cores, they have a limited lifetime as main sequence stars. This lifetime is proportional to f M / L, where f is the fraction of the total mass of the star, M, available for nuclear burning in the core and L is the average luminosity of the star during its main sequence lifetime. Because of the strong dependence of luminosity on mass, stellar lifetimes depend sensitively on mass.[1]
• The lifetime of the sun is about 100 million years. The life of stars of 10 times weight of the sun is from 1 / 1000 to 1 / 100.
The Sun formed about 4.6 billion years ago.  It will exit the main sequence in approximately 5 billion years and start to turn into a red giant. [2]

Refereces
1.   The Life and Death of Stars  NASA
2.   WikipediaSun

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