I. Interstellar Medium refers to the gas and dust between stars. II. A nebula is a dense cloud of dust and gases that begins to contract due to gravity, increasing pressure and temperature to form a protostar. III. When the protostar gets hot enough, fusion begins and a main sequence star is born.

1. Life Cycle of Stars

2. I. Interstellar Medium II. Nebula III. Protostar IV. Main Sequence V. Red Giant VI. Supernova V. White Dwarf

4. _____________ _____________ is the total mass of the gas and dust between the stars. Interstellar Medium

5. _____________ a dense cloud of dust and gases. NEBULA

6. The nebula begins to contract due to __________ and the pressure and temperature increase and becomes a ________________. GRAVITY PROTOSTAR

7. When the temperature gets hot enough, _______________ begins and a _______ ____________ star is born. FUSION MAIN SEQUENCE

8. A star loses ____________ during fusion as energy is released. This decreases the star’s gravity. A star will expand, becoming a _________, when the outward force of __________ is greater than the inward force of ___________. mass RED GIANT fusion gravity

9. As the fuel runs out in a star, _________ slows down. When the ______________ force of fusion is less than the ____________ force of gravity, the star will shrink in size, becoming a _________ _________. fusion outward inward WHITE DWARF

10. A SUPERNOVA is an EXPLOSION that marks the end of a very massive star’s life.

11. Small and medium stars become __________________ once they die. Larger stars become novae and die as: ____________ NEUTRON STAR BLACK DWARVES

13. Hertzprung-Russell Diagram

23. Life Cycle of Stars