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Most stars use hydrogen as their fuel, fusing the hydrogen nuclei into helium and radiating the energy that this releases. The helium acts as a sort of "nuclear ashes" in the solar fireplace.

When a star grows old, the amount of helium "ash" in the core of the star begins to interfere with the hydrogen fusion, and the star begins to collapse. The collapsing star generates heat through the increasing pressure and density of the core, and at some point, the helium in the core gets so hot and so dense that the helium itself begins to fuse into carbon and oxygen. At that point, the star expands into a red giant.

Very much like the Sun itself will, in about 4 billion years.

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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.


Why wont the sun last forever?

The sun is powered by nuclear fusion in its core, converting hydrogen into helium. Eventually it will run out of hydrogen fuel and start fusing helium, leading to its expansion into a red giant and eventually shedding its outer layers, forming a planetary nebula. This process will happen in about 5 billion years.


When the sun ages after awhile what does it contain?

As the sun ages, it undergoes processes that lead to the depletion of its hydrogen fuel in the core. This results in the expansion of the outer layers, turning the sun into a red giant. Eventually, it will shed its outer layers to form a planetary nebula, leaving behind a dense core called a white dwarf composed mostly of carbon and oxygen.


What element is the main fuel for red giant stars?

The main fuel for red giant stars is helium. In the core of red giant stars, hydrogen fusion has ceased, and as the star evolves, it starts fusing helium into heavier elements like carbon and oxygen. This process produces the energy that sustains the star's outer layers and causes it to expand and cool, creating a red giant.


9 stages of a star?

Stellar nebula: a cloud of gas and dust in space. Protostar: a young star still forming through gravitational collapse. Main-sequence star: stable fusion of hydrogen into helium in the star's core. Red giant: expansion of the star as it runs out of hydrogen fuel. Helium fusion: fusion of helium atoms in the core. Planetary nebula: outer layers of the star expelled into space. White dwarf: the core left behind after the outer layers are ejected. Black dwarf: a cooled and dim white dwarf. Supernova or black hole: the final stage, depending on the mass of the star.

Related Questions

Is the sun homogeneous?

No; the center is much denser, and hotter, than the outer layers. Also, the center has a higher percentage of helium - which means that more fuel (hydrogen) has been burned up already.No; the center is much denser, and hotter, than the outer layers. Also, the center has a higher percentage of helium - which means that more fuel (hydrogen) has been burned up already.No; the center is much denser, and hotter, than the outer layers. Also, the center has a higher percentage of helium - which means that more fuel (hydrogen) has been burned up already.No; the center is much denser, and hotter, than the outer layers. Also, the center has a higher percentage of helium - which means that more fuel (hydrogen) has been burned up already.


When do scientist estimate will the sun run out of fuel?

In about 5 billion years, it will enter a red giant phase, its outer layers expanding as the hydrogen fuel in the core is consumed and the core contracts and heats up See link for pictorial


What is an expanding star after exhausting its hydrogen fuel called?

An expanding star after exhausting its hydrogen fuel is called a red giant. This stage occurs when the core contracts and heats up, causing the outer layers of the star to expand and cool, giving it a red color.


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.


What does a star become when it expands and outer layers cool?

When a star expands and its outer layers cool, it becomes a red giant. This occurs in the later stages of a star's life cycle, particularly for stars with masses similar to the Sun. The expansion is caused by the star running out of hydrogen fuel in its core and beginning to fuse helium into heavier elements.


When a star has fuel left and its outer layers escape into space it is a?

It is called a nova.


Why wont the sun last forever?

The sun is powered by nuclear fusion in its core, converting hydrogen into helium. Eventually it will run out of hydrogen fuel and start fusing helium, leading to its expansion into a red giant and eventually shedding its outer layers, forming a planetary nebula. This process will happen in about 5 billion years.


A star that has expanded and cooled is what?

A star that has undergone expansion, deflation and cooling is known as a white dwarf, or degenerate dwarf. It is a small star made up of mainly electron-degenerate matter.


When the sun ages after awhile what does it contain?

As the sun ages, it undergoes processes that lead to the depletion of its hydrogen fuel in the core. This results in the expansion of the outer layers, turning the sun into a red giant. Eventually, it will shed its outer layers to form a planetary nebula, leaving behind a dense core called a white dwarf composed mostly of carbon and oxygen.


What element is the main fuel for red giant stars?

The main fuel for red giant stars is helium. In the core of red giant stars, hydrogen fusion has ceased, and as the star evolves, it starts fusing helium into heavier elements like carbon and oxygen. This process produces the energy that sustains the star's outer layers and causes it to expand and cool, creating a red giant.


Which star expands due to fusion?

As a star ages and runs out of fuel in its core, it can expand in size as it transitions into a red giant. During this phase, fusion reactions occur in the outer layers of the star, causing it to expand and cool. This expansion happens when the star exhausts its hydrogen fuel and begins fusing helium in its core.


9 stages of a star?

Stellar nebula: a cloud of gas and dust in space. Protostar: a young star still forming through gravitational collapse. Main-sequence star: stable fusion of hydrogen into helium in the star's core. Red giant: expansion of the star as it runs out of hydrogen fuel. Helium fusion: fusion of helium atoms in the core. Planetary nebula: outer layers of the star expelled into space. White dwarf: the core left behind after the outer layers are ejected. Black dwarf: a cooled and dim white dwarf. Supernova or black hole: the final stage, depending on the mass of the star.