Nuclear Fusion

In the article, “First Detailed Image of Accretion Disk Around a Young Star“, by Matt Williams from, talked about about nebula hypothesis which basically means that solar systems are form from huge clouds of gas and dust. When gravitational collapse occurs at the center ( center of the star), the remaining gas and dust creates an accretion disk. A team of astronomers recently captured the first clear image of a young star surrounded by an accretion disk. With this information, astronomers are now able to study it in detail never thought possible with past technology. The star captured in the picture was named HH 212.

This article relates to our conceptual objective, “I can describe how stars form and produce energy in their cores by nuclear fusion”, because it explains the basics of the formation of a star. A star can form when a cloud of gas and dust collapse in a center due to a gravitational force. These gases and dust form the star’s core and gets increasing energy and heat as more matter gets pulled in. The star also gets more dense during this process. This process forms an early stage of a star called a protostar. The remaining matter (gases/dust) forms accretion disk that orbits the star. When the center becomes a certain level of temperature and density, nuclear fusion begins. During the fusion reaction, hydrogen atoms are combined together to form helium atoms. Photons of light are emitted once with fusion occurs. But, once the outward pressure (energy out) balances out with the inward gravitational collapse of gases and dust( energy in), a state of hydro-static equilibrium is achieved. In class, we learned this material through our lecture-tutorial about star formation and lifetimes. These pages were 119-120 and they talked about the energy formed and emitted by stars and how they were created. The energy use to produce nuclear fusion is the material left over after the gravitational collapse of gases and dust in the accretion disk. Once the protostar reaches hydro-static equilibrium, the protostar becomes a main sequence star.

After reading the article, I was surprised we were only recently able to take detailed pictures of this disk. Basically that nebula hypothesis was only a hypothesis after all and now it has been proven true. Learning about the formation of stars can help us determine the past of our solar system and system that will be discovered in the future.


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