Answer:
What is the formation of heavier elements during star formation and evolution?
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Patrick Fenex
Answered November 13, 2019
All stars irregardless of their mass, from hypergiant stars, to the smallest m class dwarfs begin their lives converting hydrogen gas into helium has using nuclear fussion to start the process of nucleosynthesis. This initial phase of nuclear fussion is known as the main sequence. A star like the Sun is known as a G2V yellow dwarf. The G, stands for the dwarf star classification. G is second most massive group of dwarf stars. F being the most massive dwarf stars, and M being the least massive. The 2 represents the scale between 0 through 9 in that classification. The V stands for main sequence. A star like the sun will remain on the main sequence for at least another four billion years. It has already been a main sequence star for over 4.6 billion years. How do scientists know this? By studying meteorites and lunar samples brought back by the Apollo astronauts. They could very accurately carbon date these samples to a very precise origin. Thus the Sun cannot be any older than that. Massive stars live maybe 10% of the Sun's age before they end their lives in a supernova explosion.Once the ratio of helium build up in the core reaches a critical limits, a process known as the helium flash occurs. This signifies the end of the main sequence stage. As the star begins to burn helium in the core, the remaining hydrogen continues to fuse hydrogen into helium in an outer shell outside the core. Since helium is as nearly as efficient at releasing energy when it is using fussion to convert helium in to carbon, the outer layers begin to swell into a gargantuan object known as a red giant star. It is thought that when the Sun becomes a red giant, that it's diameter will be greater than the diameter of Earth's orbit around the sun. That is the end of our sun's productive life cycle. There is not enough mass in the sun to fuse the next stage of nucleosynthesis. The outer layers of the sun simple drift away, and form a beautiful planetary nebula. Where the next generation of stars will form.
