the life cycle of a star

• what are produced during the fusion processes in a star?

  all of the naturally occuring elements
• how are elements heavier than iron produced?

  supernova
• how are elements distributed throughout the universe

  explosion of a supernova
• why is a star stable in the main sequence stage of its life cycle?

  gravitational force inwards & forces as a result of fusion outwards are in equilibrium
• what is the life cycle for all stars?

  1. form in a cloud of dust & gas (nebula) by gravity
  2. forms a protostar
  3. fusion begins - hydrogen to helium
  4. fusion of small nuclei into larger nuclei
  5. main sequence star - stable period where gravitational forces inwards balance forces outwards due to fusion
  6. hydrogen begins to run out
  7. helium nuclei fuse to make heavier elements up to iron
• what happens to stars the same size as the sun?

  1. expand to become a red giant
  2. collapse to white dwarf
  3. cool to black dwarf
• what happens to stars much bigger than the sun?

  1. expand to become a super red giant
  2. explode in a supernova creating elements heavier than iron & distributing them throughout the universe
  3. become either a neutron star or black hole