The article posted to, “Nuclear Fusion In Stars”, relates to our 13th objective, “I can describe how stars form and produce energy in their cores by nuclear fusion” accordingly. The article goes into depth about the exact process formed by the stars and how the process happens. To begin, we are informed that stars begin life as a cloud of gas and dust, eventually collapsing inward and that stars output so much energy because of the nuclear fusion taking place in their cores. The collapse of the material causes the center of the star to become very hot and dense. The article informs us that these high pressures taking place is essentially what allows nuclear fusion to convert hydrogen atoms into helium atoms through the multi-stage process.

The proton-proton chain that fuels nuclear fusion inside the core of our Sun. Credit: Ian O'Neill

The nuclear fusion process begins by two hydrogen atoms merge together to create the deuterium atom. The deuterium atom merges with another hydrogen atom to form an isotype of helium -3, which two of the helium-3 nuclei comes together to form a helium-4 atom. This process releases a lot of energy in the form of gamma rays, which are absorbed and re-emitted from atom to atom and brings down the energy of the rays. This allows us to see the visible range we notice coming off of the surface of the stars. The article also informs that this fusion cycle is known as the proton-proton chain, which in a long story short is the chain of reactions by which low-mass stars (including the sun) fuse hydrogen to helium. The stars are able to produce energy if they have hydrogen fuel in their cores, but once the hydrogen runs out then the fusion reaction is terminated and the stars then shrink and cool. The stars then either can become white dwarfs or other larger stars can continue the fusion process, aka the more mass equals more fusion. This is quite the process, but because the fusion rate is so sensitive to temperature, gravity, and energy balance act together to keep this rate steady. With this information from the article, helped me make a connection the our class on this matter. From our lecture tutorial book, page 119, we were given a chart example of the mass of the star and approximate main sequence lifetime of the star and were able to identify that low-mass stars live longer opposed to high-mass stars. With this information from both this in depth article and from the book, i was able to tell that the rate of nuclear fusion in a high-mass star is greater than the rate of nuclear fusion in a low-mass star, which is essentially why the high-mass stars are shorter to live and end the nuclear fusion more quickly. I found this article to help me understand the process of nuclear fusion in an easy and informative way that helped me with this objective accordingly. Although learning this material was fast and even a little overwhelming at first due to the process of nuclear fusion being something i was learning about for the first time, i found myself engaging in the material and finding it very interesting of how the stars form and produce energy.


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