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Which stage of stellar evolution does combined hydrogen fusion and helium fusion cause a star's outer shell to expand?
Wiki User
∙ 14y ago
Main Sequence - star is stable because of Hydrostatic Equilibrium. Fusing Hydrogen to Helium in core. Stars spends about 90% lifetime as main sequence.
This is were I found the answer - http://www.maa.mhn.de/Scholar/star_evol.html
Wiki User
∙ 14y ago
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What is the correct sequence for stellar evolution?
Stellar evolution states that stars are powered by a hydrogen fusion reaction. When a star has burned up its hydrogen, this reaction runs out, and its core will contract and heat up causing the hydrogen shell to ignite. This causes the star to expand into a giant star. Depending on the solar mass of the star, it will evolve into different objects. If its mass is in the 0.3 to 3 range, its core, now fusing helium will degenerate before the helium has a chance to ignite, and the explosion that results will be absorbed into the star itself. A star with a mass less than 0.4 will evolve into a white dwarf. If its mass is between 0.4 and 0.3, it will become a red giant and then burn out into a white dwarf. Stars that are more massive will collapse explosively as a super nova, and if it is larger than 25 stellar masses, it will be a neutron star.
When does hydrogen expand?
Hydrogen gas expands when it is heated.
Point in stellar evolution when a star has used up all its fuel?
When a star has used up all the hydrogen in its core, it has reached the end of the main sequence. Subsequent developments depend on the mass and composition of the star. Sun-type stars may expand and continue to fuse ever heavier elements in and about their core, until fusion no longer yields sufficient energy to prevent collapse.
What causes air to expand?
hydrogen and gases
What is the evolutionary end of the sun?
Based on current theories of stellar evolution, billions of years in the future our Sun will expand to a red giant, shed much of its outer envelope, and become a white dwarf. After this it will probably cool over an extremely long time and likely end up as a black dwarf.
Why does water expand instead of increaing?
due to hydrogen bond
Do stars expand in size?
Stars expand in size to become red giants, when they start running low on Hydrogen fuel.
What type of bonds cause water to expand when it freezes?
Hydrogen bonds
How do you lower the density of the hydrogen gas?
You can lower the density of hydrogen (or any) gas by heating it in a container where it is free to expand, like a balloon.
Does water freeze when it expands?
Yes. Water is one of the few substances on earth that does expand when frozen most other things expand when heated. The hydrogen bonds between the hydrogen and oxygen atoms straighten and the water molecule expands.
Is the sun a main sequence star?
A "Main Sequence" star does not "really exist". The term "main sequence" refers to a period in a stars life when it is basically converting hydrogen into helium. Once it has consumed all of the hydrogen, a star will evolve out of main sequence into stellar remnants. The main sequence is a continuous and distinctive band that appear on plots of stellar colour versus brightness on the Hertzsprung Russell diagram. Our Sun is smaller and a little more yellow than most other main sequence stars, which are white. It will gradually run out of hydrogen fuel in another 5 billion years, at which point it will expand to become a red giant. After that it will dim, cool down, and fade into a white dwarf. See related question on the life of a star.
Is the sun the main-sequence star?
A "Main Sequence" star does not "really exist". The term "main sequence" refers to a period in a stars life when it is basically converting hydrogen into helium. Once it has consumed all of the hydrogen, a star will evolve out of main sequence into stellar remnants. The main sequence is a continuous and distinctive band that appear on plots of stellar colour versus brightness on the Hertzsprung Russell diagram. Our Sun is smaller and a little more yellow than most other main sequence stars, which are white. It will gradually run out of hydrogen fuel in another 5 billion years, at which point it will expand to become a red giant. After that it will dim, cool down, and fade into a white dwarf. See related question on the life of a star.
