Ryan Chen #10236, Sam Grace #10196Mr. ConstantinidesScience 8, Period 619 April 2014The life of the starsStars are the night lights of the universe. While they may seem endless, they don't last forever. Each star follows its own unique life cycle. The life of a star can be divided into six phases, and there are three paths of phases that a star can follow in its life. Nebulae are the first phase of a star's life cycle. Nebulae serve as the nursery of the universe. A nebula is a huge cloud made of dust and gas. They can span light years and have a very blurry appearance. The primary gases present in a nebula are hydrogen and helium gases. Not all nebulae are the same. They can range from blue to red to pink and can be shaped like crabs, eagles or simply a large ball of dust. There are different types of nebulae. Emission nebulae are nebulae that form when gas and dust collapse on themselves and the young star begins to release ultraviolet radiation. These types of nebulae have very high temperatures because newborn stars blast the surrounding area with sizzling beams of energy-filled particles. Reflection nebulae do not have enough contained energy to release radiation like emission nebulae. However, they are still visible, as the gas clouds they are in help reflect their light. Another type of nebulae are planetary nebulae, which occur towards the end of a star's life. Although planetary nebulae have the word "planet" in their name, the only thing they have to do with planets is that they are similar to them. These nebulae form when a medium-sized star runs out of fuel and sheds its gas into rings of colored light. Another type of nebulae, called dark nebulae, are interstellar clouds with dust so composed... in the center of the paper... low-mass or high-mass protostars form. The low-mass protostar then goes on to form the average star, just like our Sun. The high-mass protostar goes on to form blue giant stars. Medium stars, after burning all their hydrogen, begin to burn helium, forming a red giant. Blue giants undergo the same process but become red supergiants instead. Once the red giant burns all its helium, the star stops burning and disperses its gas into a planetary nebula. The red supergiant suddenly shuts down when it runs out of fuel and explodes in a supernova. The planetary nebula then slowly fades into a white dwarf. This white dwarf burns the rest of its energy until it becomes a black dwarf. The supernova can then become a neutron star or a black hole. The life of stars is one of the most complex and at the same time majestic processes that the universe can show.