High Mass Stars Research Paper

The Life of High Mass Stars High mass stars can be classified as any star that is at least four times the solar mass of our star, the sun. They consist of about three percent of all of the stars in the universe, but there are still billions and billions of them all over the universe. High mass stars, like low mass stars, begin to form from clouds of gas and dust in space. They both begin as a protostar and eventually become dense enough to cause hydrogen fusion within them; placing them both on the main-sequence. The only difference is high mass stars are able to get through this process quicker due to their increased gravity from their higher mass. Once the hydrogen is used up, like low mass stars, high mass stars start to form shells of heavier elements up to carbon. Then unlike low mass stars they are able to form shells of heavier elements like silicon and iron. Once the star has formed iron, it can no longer fuse starting the beginning of the end of the stars life. High mass star’s ultimate fate is to succumb to the pressure from gravity and end its life. The star releases all of its energy in an explosion called a supernova, leaving behind a star of all of the neutrons left packed tightly together in what is called a neutron star. The neutron star will either become too dense collapse
further and become a black hole or fizzle out after it has released all of its energy. In this paper I intend to look at the life and death of high mass stars. Any star in the universe begins its life in the same way. First, a cloud of gas and dust starts to spin and the cold temperatures and high densities of the cloud allows the gravity to overcome thermal pressure that will begin the gravitational collapse that will form the star. Once this happens a protostar will appear. A protostar is like a star, but its core is not hot enough to create fusion. The length of time at which it takes a protostar to become a main sequence star depends entirely on it’s mass. The lower the mass of the star the longer it will take for the core to be able to fuse hydrogen. Once a star becomes hot enough to fuse hydrogen, usually around ten Kelvin, then it can be considered a main sequence star. Main sequence stars are stars that fuse hydrogen to create helium atoms in their core. The reason they are called main sequence stars is because the lie along a plot on the H-R diagram where ninety percent of all stars in the universe lie on the graph. One difference between high mass and low mass stars is that while they both fuse hydrogen, high mass stars use carbon, nitrogen, and oxygen as catalyst. Once a high mass star has left the main sequence, it begins a process of shell burning. Shell burning occurs when a high mass star burns up all of it’s hydrogen and begins to burn up a heavier element, helium. Once all of the helium has been burned up the star begins to burn up an even heavier element carbon. Before a high mass star can begin to fuse carbon it experiences a helium flash. A helium flash is a runaway nuclear fusion event that results in helium being fused into carbon-12. Once the helium is all burned up, the star begins to fuse carbon-12 into nitrogen, then neon into oxygen, then oxygen into silicon, the silicon into iron. Once the stars fusion reaches iron it can no longer fuse because the energy required to fuse two iron atoms together is more than the energy the fusion would put out. Once the core of a star has reached iron it can no longer support itself against the gravity pushing down on it. The intense temperatures and densities cause the star to collapse on itself. This triggers a great explosion called a supernova, sending heavier elements out into the universe. It is believed that all of the gold in existence has come from supernovae (LCGOT). Once a star goes supernova it leaves behind either a neutron star or the pressure becomes so great the it actually creates a black hole. A neutron star is the remnant of a supernova. The result is a star with all of it protons and electrons fused together to form a star composed of only neutrons. The star left behind is roughly about the size of a U.S. city, nut denser than anything else in the universe. One teaspoon of a neutron star would weigh a billion pounds (NASA). A neutron star will send out pulsars for the rest of its life and then fizzle out or grow and become a magentar that will ultimately end in it becoming a black hole. A black hole is an area of space where the gravity is so strong that not even light can escape its gravitational pull. Black holes are a result of the death of a high mass star. Scientist believe there is a super-massive black hole at the center of our galaxy. After a black hole is formed it continues to grow by consuming its surroundings. High mass stars can be classified as any star that four times or more the solar mass of our sun.
Although there are billions of them out in the universe they only consist of about three percent of the total amount of stars in the universe. High mass stars and low mass stars share a lot of similarities in the beginning of their life including how they are formed. High mass stars go through their life cycle much faster than low mass stars. What ultimately separates the two is the way they end their life cycles. High mass stars often go out with a bang, creating a supernova that could potentially create a black hole. Sometimes instead the explosion will create a neutron
star.