GCSE Physics (AQA)

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Birth of a Star

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Space physics Solar system; stability of orbital motions; satellites

Birth of a Star

3:39 Life Cycle of a Star
Spec 4.8.1.1 4.8.1.2
Previous Comparing Orbits Next Red Giants & Supergiants
  • Dust and gas in space are drawn together by gravity, forming a protostar.
  • Understanding the life stages of a star is essential for exams.
  • Dust and gas, mainly hydrogen, gather due to gravitational attraction.
  • A protostar forms when enough gas and dust are pulled together.
  • As more dust and gas accumulate, the protostar becomes denser and larger.
  • Increased particle collisions in the protostar generate heat.
  • The protostar becomes denser and hotter as it grows.
  • Gravitational force causes hydrogen gas to heat up, leading to nuclear fusion.
  • Nuclear fusion involves small nuclei fusing into a larger nucleus, releasing energy.
  • Fusion occurs under high temperature and pressure conditions in the protostar.
  • Helium atoms form from hydrogen fusion, marking the first fusion reaction in a star's life.
  • Energy from fusion reactions heats and brightens the protostar, making it a star.
  • The star resembles the sun, which is in this life stage.
  • Fusion of hydrogen into helium releases energy as heat and light.
  • This energy reaches Earth, warming the planet and sustaining life.
  • Stars maintain equilibrium between outward fusion pressure and inward gravitational force.
  • Gravity pulls matter towards the star's center, potentially causing collapse.
  • Fusion energy creates outward pressure, balancing gravitational forces.
  • The star remains in equilibrium, preventing collapse or explosion.
  • Understanding this equilibrium is crucial for explaining how stars work.

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