Notes

Stars are like all living things: they are born, they go through their life cycle, and die. A nebula is a cloud of gas and dust spread out in a mass volume. They are also the beginning of the creation of stars. Gravity can pull the dust and gas together. The nebula theory suggests that the sun and planets formed from a rotating disk of dust and gases. The nebula turns into a protostar which is the earliest stage of a star's life. It becomes a protostar when the nebula becomes extremely dense. A star's mass determines how long a star will live: low masses will make them live longer and use up fuel slowly (up to billions of years). This is what happens to low mass stars. The red giant comes after the main sequence star and occurs when they start running out of fuel. Eventually, the outer layer grows larger and breaks apart from the rest of it which forms a planetary nebula. The blue-white core of the star is left behind and cools to form a white dwarf. Now onto high mass stars. Starts out similar to the other (I didn't catch what it said). Then it becomes a supergiant when it starts running out of fuel. After that it either turns into a black hole or neutron star. Neutron stars are denser and smaller than white dwarfs. Sorry if I missed a few things.