topic 78

• what is a nebula

  • collectio of dust and gas
• how does a star nebular become a proto star

  • force of gravity pulls dust and gas to become a protostar
  • temperature rises as the protostar gets dense
  • high enough temperature hydrogen nuclei undergo nuclear fusion
• proto to main sequence

  • outward pressure from nuclear fusion is balanced by the inward pressure of gravity causing the star to remain stable
  • main sequence star
• main sequence to red giant

  • hydrogen in the sar begins to run out causing inward gravitional force to be the dominant force and compress the star
  • until nuclear fusion is able to under go nuclear fusion and causing the star to expand
  • sun size or smaller - red giant, bigger super red giant
• if the planet is smaller or the same size after red giant

  • becomes unstable and expelles it's outer layers leaving a white dwarf
  • cools to a black dwarf as it emits all it's energy
• bigger than the sun

  • bigger than the sun after a red super giant undergo fusion and do many expansions and contractions| to make heavy elements and explode in a supernova
  • outerlayers are thrown into space leaving a very dense core called a neutron star
  • if it's a mass star than after supernova black hole