It all starts with 1. ____________, cloud of gas and dust particle in outer space.
Due to the force of gravity, the 2. ____________ gas is pulled together and eventually
became a protostar. Nebular fusion occurs at the center of the protostar and becomes
stable. During this time, hydrogen is converted into 3. _____________ forming main
sequence star. The size of the star can be average or massive. A massive main
sequence star that runs out of hydrogen fuel will begin to expand and cool down.
This is 4. ________________, the collective term for massive stars in the universe. The
red super giant continues to fuse with heavy elements and stops when 5. ___________
is converted in the core of the star. At this point, red super giant will become a