Life Cycle of a Star

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Life Cycle of a Star

Explanation 1                

  • Particles in space, which are leftover remains of old stars, combine together to form a new star in the nebula. The particles are pulled together by a gravitational pull. 
  • As the particles are pulled together nuclear reactions begin within the core. This star is called a protostar until it reaches 10 million degrees. 
  • If the mass of particles is large enough, it is called a supergiant, and will burn for 10 million years. Larger stars burn their fuel more quickly and inefficiently. 
  • When the hydrogen nuclear fuel begins to run out, it will expand into a large red giant and begin to burn the rest of its gasses. 
  • After the nuclear reactions end in the core, it begins to cool and its great gravitational forces will cause it to collapse in on itself. 
  • This collapse will cause a huge explosion or Supernova and blow particles out into space to form a nebula, which causes the cycle to start over again. 
  • The dense body left over that collapsed in on itself, is called a Neutron Star, and has a mass of one hundred million tons for every thimbleful. 
  • If the mass of the supergiant is great enough it can form what we call a black hole. 
  • Since our sun is not a supergiant, but instead a medium yellow star, it will have a different fate. It will eventually use up its fuel in about 10 billion years, swell into a red giant, and then shrink down to a white dwarf. When it has completely cooled it will be a cold black dwarf. 

* Scientists feel our sun is already 4.5 billion years old and expect it to be around for another 5.5 billion years.

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Explanation 2

  • Stars are born from clusters of interstellar matter

Outer space is not an absolute vacuum. In fact, it is filled with very thin clouds of hydrogen and helium, and dust-like interstellar particles. These are the raw materials of future stars. Clusters of interstellar particles attract more and more other particles, gradually increasing in size. Eventually, the cluster begins to contract by virtue of its own gravity. Then, when the core temperature has reached around 10 million degrees, a nuclear reaction begins. The period up until this point is known as the "contraction phase" and, in the case of ...

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