<p>Stars are rotating, but that's not the cause for their stability.</p>

<p>The stability is caused by the <a href="http://en.wikipedia.org/wiki/Hydrostatic_equilibrium" rel="nofollow">hydrostatic equilibrium</a> between gas/plasma pressure and gravity. The pressure is mainly caused by the heat of several millions degrees.</p>

<p>More details <a href="http://en.wikipedia.org/wiki/Stellar_structure" rel="nofollow">here</a>.</p>

CC BY-SA 3.0
2014-02-28T01:31:08.607Z
More clearly, I would say that the pressure is granted by thermonuclear fusion reactions, releasing enough radiation to support the gravity force. It is radiation pressure that "pushes outward" the stellar mass.
Py-ser
CC BY-SA 3.0
2014-02-28T09:09:29.213Z
Radiation pressure is one of several terms adding up to total pressure. Heat is provided by adiabatic compression, and as you state, mainly by thermonuclear fusion.
Gerald
CC BY-SA 3.0
2014-02-27T18:00:14.713Z
2014-02-27T18:00:14.713Z
Gerald
<p>Like Chris said above, stars rotate to conserve their angular momentum. They have an initial angular momentum from their formation. In a stellar system both energy and momentum, must be conserved for the system to be stable. Throughout the evolution, the system may radiate some angular momentum away in the form of gravity waves (ie. double degenerate binaries). During this process the separation of two stars will be reduced and the rotation rate of the star will spike to conserve angular momentum.</p>

<p>More on this here: <a href="http://www.selmademink.com/science/on-the-origin-of-stellar-rotation-rates-and-the-role-binary-interaction/" rel="nofollow">http://www.selmademink.com/science/on-the-origin-of-stellar-rotation-rates-and-the-role-binary-interaction/</a></p>

CC BY-SA 4.0
2021-06-21T01:53:43.090Z
But why is the initial angular momentum not zero? In that case *stars would NOT rotate to conserve their angular momentum.*
uhoh
CC BY-SA 3.0
2014-03-02T03:14:43.867Z
2014-03-02T03:14:43.867Z
momitoburrito
<p>Stars rotate due to the angular momentum of the gas they formed from. This angular momentum must be conserved, and remains as the rotation of the star and it's satellites. If a star collapsed from a completely static gas cloud it would not rotate, but would still be stable. The stability is provided by the hydrostatic equilibrium between radiation and thermal pressure with gravitation collapsing the star - not the stars rotation. </p>

<p>I don't know any statistics but I expect all stars rotate to some degree; It is usually the turbulence of gas clouds that leads to overdensities that then collapse in to stars. </p>

CC BY-SA 3.0
2014-02-28T13:45:25.853Z
2014-02-28T13:45:25.853Z
christopherlovell
<p>This question may sound silly but I'm really not pretty sure whether stars are rotating or stationary. If they are not rotating what makes them to be stable?</p>

CC BY-SA 4.0
2021-06-21T01:55:27.007Z
I think there is a new question possible, something like "Haver there ever been theoretical predictions of the distributions of rotation rates for a given start type in a given galaxy?"
uhoh
<star>
Are stars rotating?
Praveen Kadambari
# Are stars rotating?

(Asked by: username_0 on 2014-02-27)

This question may sound silly but I'm really not pretty sure whether stars are rotating or stationary. If they are not rotating what makes them to be stable?

**Tags:** star

> **Comments:**
> **username_1**: I think there is a new question possible, something like "Haver there ever been theoretical predictions of the distributions of rotation rates for a given start type in a given galaxy?"  

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## 3 answers

### Answer by username_5 on 2014-02-28. Score: 5 | Accepted answer

Stars rotate due to the angular momentum of the gas they formed from. This angular momentum must be conserved, and remains as the rotation of the star and it's satellites. If a star collapsed from a completely static gas cloud it would not rotate, but would still be stable. The stability is provided by the hydrostatic equilibrium between radiation and thermal pressure with gravitation collapsing the star - not the stars rotation.

I don't know any statistics but I expect all stars rotate to some degree; It is usually the turbulence of gas clouds that leads to overdensities that then collapse in to stars.


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### Answer by username_2 on 2014-02-27. Score: 3

Stars are rotating, but that's not the cause for their stability.

The stability is caused by the [hydrostatic equilibrium](http://en.wikipedia.org/wiki/Hydrostatic_equilibrium) between gas/plasma pressure and gravity. The pressure is mainly caused by the heat of several millions degrees.

More details [here](http://en.wikipedia.org/wiki/Stellar_structure).

> **Comments:**
> **username_3**: More clearly, I would say that the pressure is granted by thermonuclear fusion reactions, releasing enough radiation to support the gravity force. It is radiation pressure that "pushes outward" the stellar mass.  
> **username_2**: Radiation pressure is one of several terms adding up to total pressure. Heat is provided by adiabatic compression, and as you state, mainly by thermonuclear fusion.  

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### Answer by username_4 on 2014-03-02. Score: 0

Like Chris said above, stars rotate to conserve their angular momentum. They have an initial angular momentum from their formation. In a stellar system both energy and momentum, must be conserved for the system to be stable. Throughout the evolution, the system may radiate some angular momentum away in the form of gravity waves (ie. double degenerate binaries). During this process the separation of two stars will be reduced and the rotation rate of the star will spike to conserve angular momentum.

More on this here: <http://www.selmademink.com/science/on-the-origin-of-stellar-rotation-rates-and-the-role-binary-interaction/>

> **Comments:**
> **username_1**: But why is the initial angular momentum not zero? In that case *stars would NOT rotate to conserve their angular momentum.*  

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