the life cycle of a star

• The life cycle is determined by

  the size of the star.
• black dwarf

  a star that has faded out and gone cold
• black hole

  an object in space that has so much mass that nothing, not even light, can escape from its gravitational field
• What word is used to describe a cloud of dust and gas

  a nebula
• What type of reactions take place at the start of a star's life cycle?

  fusion reactions
• What is the life cycle of a star determined by?

  the size of the star
• what do fusion reactions lead to

  fusion reactions lead to an equilibrium between the gravitational collapse of a star and the expansion of a star due to fusion energy
• What is the life cycle of stars smaller or the same size as the sun?

  Nebula - Protostar - main sequence star - red giant - white dwarf - black dwarf
• What is the life cycle of stars much bigger than the sun?

  Nebula - Protostar - main sequence star - red super giant - supernova - black hole + neutron star
• What are produced during the fusion processes in a star?

  all naturally occurring elements
• What condition is required for fusion reactions to occur in a star?

  very high temperatures
• What type of elements are produced in a supernova?

  elements heavier than iron
• What type of nuclei fuse together to form heavier elements in a star?

  Hydrogen nuclei fuse to form heavier elements
• Explain why the star is stable while it is in the main sequence stage of its life cycle

  gravitational force inwards and forces as a result of fusion reactions outwards are in equilibrium
• Describe what will happen to the star between the main sequence stage and the end of the star's life cycle


  the star will expand to become a red giant and then will collapse to become a white dwarf and then cool to become a black dwarf