Star Collapse: Why Not in Early Stages?

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SUMMARY

A star does not collapse in its early stages due to the radiation pressure generated by fusion reactions in its core, primarily involving hydrogen. As a star ages, it exhausts its hydrogen fuel and transitions to helium and heavier elements, leading to a decrease in energy production. Eventually, when the star can no longer sustain fusion reactions, it collapses under its own gravity. Cepheid variables exemplify this process, as they undergo cyclical phases of collapse and expansion over billions of years.

PREREQUISITES
  • Understanding of stellar evolution and fusion processes
  • Knowledge of radiation pressure and its role in star stability
  • Familiarity with the lifecycle of hydrogen, helium, and heavier elements in stars
  • Concept of Cepheid variables and their significance in astrophysics
NEXT STEPS
  • Research the process of stellar nucleosynthesis and element formation in stars
  • Explore the mechanics of radiation pressure and its effects on star stability
  • Study the lifecycle of Cepheid variables and their role in measuring cosmic distances
  • Investigate the conditions leading to supernova events and black hole formation
USEFUL FOR

Astronomers, astrophysics students, and anyone interested in the lifecycle of stars and the processes governing stellar stability and evolution.

bassplayer142
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Why doesn't a star collapse in the early stages of its life instead of the later. You would think that with less gas at the end stages gravity would weaken and not allow a black hole.
 
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A star is held up by the energy (actaully radiation pressure) given off by the fusion reaction in the centre. A young star is mostly hydrogen which reacts rather well, as a star ages it uses up hydrogen in the core, then Helium, Carbon etc until it gets to a material that won't easily react. As there is no more energy it then collapses.
A star loses a negligible amount of it's mass through most of it's life - mostly charged particles in the solar wind. Remember the fuel that is used in the reaction doesn't get used up, it just converts to helium which stays in the star.
 
Cepheid variables are a good example. They are relatively massive stars that cyclically collapse and expand. During the collapse phase, they reheat, and the reheating causes them to expand once again. This cycle can continue for billions of years.
 

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