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As Hydrogen burning occurs, a new core of Helium ash is formed within the H envelope. As more He is formed, more energy is released and the temperature increases. When it is hot enough, He-burning can begin, which forms a new core of Carbon. As more Carbon is formed, this core expands also. These processes cause the star to swell.
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Is it true that an average star spends 90 percent of its life as a helium burning main sequence star?
Yes, it is true that an average star spends about 90 percent of its life on the main sequence burning hydrogen into helium through nuclear fusion. This is the longest and most stable phase in a star's life cycle before it transitions into the next phase.
Do hydrogen and helium make the sun?
Yes. Well, actually, it isn't entirely made of hydrogen and helium. It's also made of carbon-based substances and methane gas. The hydrogen burning into helium is what makes the star bright. This is also known as luminosity. Which is how bright something is.
Why is the presence of large amounts of helium in the spectrum of a star generally considered a sign of age?
Stars begintheir lives burning hydrogen and converting it to helium. If there are large amounts of helium in a stellar spectrum, it would indicate that the star has been making helium for a long time - hence age.
Why do red giants expand?
Red giants expand because they have exhausted the hydrogen fuel in their cores and have started fusing helium. This helium fusion causes the outer layers of the star to swell and expand, making the star larger and cooler overall.
Is a red giant a main sequence star?
No, a red giant is a star that has just left the hydrogen burning main sequence and begun the next step, burning helium. As helium undergoes fusion at a much higher temperature than hydrogen undergoes fusion, the star expands dramatically and as it expands its outer layers cool to red heat.
What gases make the main sequence star?
Hydrogen and Helium
What fuel is Betelgeuse burning?
Betelgeuse is a red supergiant star that is primarily burning helium in its core through the process of helium fusion. In its earlier life, it burned hydrogen, but as it evolved, it exhausted its hydrogen supply and transitioned to helium burning. This fusion process generates energy that allows the star to maintain its size and brightness as it approaches the later stages of stellar evolution. Eventually, Betelgeuse will progress to fuse heavier elements until it ultimately undergoes a supernova explosion.
The helium flash converts helium nuclei into?
The helium flash converts helium nuclei into carbon nuclei through the fusion process in the core of a star. This process occurs in stars with a mass greater than about 0.8 times the mass of the Sun during the later stages of helium burning. The intense energy released during the helium flash helps stabilize the star against gravitational collapse.
What type of star burns helium?
All red giant stars will start helium fusion when their core is compressed.
Why would an old main sequence star have more helium?
Stars make Helium as they shine - so more with age.
What forms when a main sequence cools and expands?
When a main sequence star cools and expands, it evolves into a red giant star. This process occurs as the star runs out of hydrogen fuel in its core and starts burning helium, causing it to swell in size and become brighter. Ultimately, the star will shed its outer layers in a planetary nebula and leave behind a dense core known as a white dwarf.
What two elements make up the most matter in a star?
Hydrogen and Helium
