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Main Sequence Stars Research Paper

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Main Sequence stars make up about 90 percent of the stars in your universe. These stars are ones that are fusing hydrogen into helium at their cores. Our Sun is a Main Sequence Star. To create a Main Sequence star, an interstellar cloud goes through seven evolutionary stages which take approximately 40 to 50 million years.

After approximately 10 billion years after the star is considered to be a main sequence star, the hydrogen at the center of the core is depleted. This causes the nuclear fusion which had been previously fueling the star to die out. Helium replaces the hydrogen in the core, and the inner core begins to shrink due to gravity. This process speeds up once all the hydrogen is completely used up. The radius of the star has increased …show more content…

At that point, the star begins to fuse helium into carbon in the core. This is called helium fusion. In order for this to happen, the core’s density has to increase and the temperature has to reach about 100 million Kelvin. However, a complication arises when helium fusion begins. The star’s core is degenerated and the burning becomes unstable since the core is not able to accommodate the fusion. The increase of internal pressure and temperature caused by the burning of the helium leads to an astronomical increase in outward pressure. This is, eventually, able to regulate and the core is able to expand and decrease its …show more content…

The burning process continues in the outer layers of the star, and they continue to expand. They can reach a maximum radius of approximately 300 times our Sun’s! The burning in the outer layers becomes unstable and they go through a series of explosive helium-shell flashes which are brought on by the pressure in the shell and the sensitivity to changes in temperature. This process causes the outer layers to pulse as they heat and expand, and then cool and contract. The core contracts and heats up as the last of its fuel is used. It becomes so hot that it expels ultraviolet radiation into the inner parts of the surrounding cloud, ionizing it. This process is called a planetary

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