P16.2 The Life History of a Star

• What is a Nebula?

  A cloud of dust and gas
• How is a Protostar formed?

  When Gravity pulls a Nebula in on itself
• What happens after a Protostar is formed?

  Gravity becomes stronger, causing it to become denser, making more particle collisions and raising the temperature
• What happens when a Protostar gets hot?

  Hydrogen Nuclei begin to fuse into Helium Nuclei through Nuclear Fusion
• What happens after a Protostar?

  The Nuclear Fusion gives off so much energy that it becomes a Main Sequence Star
• What happens when a Main Sequence star runs out of Hydrogen?

  Gravity makes it denser and denser until Nuclear Fusion starts again, this time fusing to make Heavier elements up to Iron
• What happens if the Main Sequence Star was small/meduim?

  Becomes Red Giant
• What happens if the Main Sequence Star was big?

  Becomes Red Super Giant
• What happens to a Red Giant?

  • Becomes unstable and loses it's outer layers until it's only a hot, dense solid core (White Dwarf Star)
  • It cools down until no light can be emitted (Black Dwarf Star)
• What happens to a Red Super Giant?

  • It will expand and contract until it explodes into a Supernova, where it forms elements heavier than Iron and ejects all across space
  • If it was very big; Neutron Star
  • If it was massive; Black Hole