Describe the life cycle of a star.

1)Nebula-clouds of dust and gas mostly hydrogen gravity pulls dust and gas together 2)Protostar-Mass falls together as it gets hot. Star formed when hot enough to make helium. fusion releases energy keeping core hot 3)Main sequence star-gravity pulls in balanced by pressure due to heat-the star is stable (4)STARS ABOUT SAME SIZE AS SUN: -Red giant star-hydrogen used up larger nuclei form and expand forming red giant -White dwarf-nuclear reactoins over-contracts under gravity-becomes white dwarf, fades and changes colour as it cools -Black dwarf (4)STARS MUCH BIGGER THAN SUN: -Red super giant star -Super nova-larger star with more mass makes nuclear reactions, gets hotter, expands until explodes into supernova throwing hot gas into space Either -Black hole or -Neutron star