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It begins collapsing, which causes gravitational heating.
If the mass of the star is below a certain threshold the collapse stops, leaving a white dwarf.
If the mass of the star is above a certain threshold the gravitational heating makes the star hot enough to ignite helium fusion and the star begins making carbon. The now very hot stellar core makes the star expand to a red giant.
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Hypothesize what will happen when the sun exhausts it's supply of hydrogen?
When a main sequence star, such as our sun, exhausts it's supply of Hydrogen, fusion of Hydrogen to Helium ceases in the core. This results in cooling of the core and therefore causes it to contract. As the core contracts, the layers surrounding the star gain kinetic energy until the fusion of Hydrogen is possible in the outer layers. As these layers undergo fusion, they increase in temperature dramatically. The outer layers expand due to heat, and the star becomes massive; the main sequence star has evolved into a red giant. Fusion of Hydrogen to Helium continues in the outer layers, whilst the fusion of heavier elements such as carbon occurs in the core.
Why does a star grow larger after it exhausts its core hydrogen?
Hydrogen fusion in a shell outside the core generates enough thermal pressure to push the upper layers outward.
The sun will eventually use up its hydrogen fuel and become what?
When the sun exhausts the hydrogen in its core and become a red giant.
What type of stars are red giants?
These are stars that have exhausted their core's supply of hydrogen by switching to a thermonuclear fusion made of hydrogen in a shell that surrounds the core.
What is it called that has exhausted it's supply of hydrogen?
A star that has exhausted the hydrogen in its core will become a red giant or supergiant.
What happens to Hydrogen atoms in a star's core?
its clears air
Why does a star's hydrogen supply run out?
The nuclear fusion in a star's core converts hydrogen into helium. Therefore the amount of hydrogen in a star is constantly decreasing.
What is a star called that has exhausted its supply of hydrogen?
A star that has exhausted the hydrogen in its core will become a red giant or supergiant.
Where does hydrogen fusion occur when there is no hydrogen left in the core of a star?
If there is no hydrogen left at the core of star then hydrogen fusion cannot occur. What happens in the core of a star before that happens is that helium begins to fuse, and then the other elements going up the periodic table until carbon. And then if the star explodes into a supernova, traces of the higher elements are fused as well.
Why do stars evolve off of the main sequence?
Because they have exhausted their supply of hydrogen in the core. They might reenter the main sequence later, but that will be using hydrogen in the shell (the branch phase) rather than the core.
When the core of a star shrinks after hydrogen fusion stops the core heats up but what happens to the star?
The rest of the star expands.
Why is a 1 solar mass giant more luminous than a 1 solar mass main sequence star?
When a star exhausts the hydrogen fuel in its core, nuclear reactions in the core stop, so the core begins to contract due to its gravity. This heats a shell just outside the core, where hydrogen remainsinitiating fusion of hydrogen to helium in the shell. The higher temperatures lead to increasing reaction rates, producing enough energy to increase the star's luminosity by a factor of 1,000-10,000.
