<p>As well as being oblate, like most large spinning bodies, there is a high degree of turbulence in any heated gaseous body, whether that be large gas planets, like Jupiter, or stars.</p>

<p>Have a look at this NASA photo of the sun as an example:</p>

<p><img src="https://i.sstatic.net/FoPBO.jpg" alt="enter image description here"></p>

<p>You can see a wide range of non-spherical details.</p>

CC BY-SA 3.0
2014-02-09T21:21:50.587Z
2014-02-09T21:21:50.587Z
Rory Alsop
<p><strong>No</strong> (1. All stars rotate to some degree and hence are slightly oblate. 2. stars have no surface like a rocky planet, what we see is the photosphere, i.e. the surface from which light escapes without being (much) absorbed or scattered. This surface, however, is constantly moving due to convection. 3. close binary stars are affected by their partner's tide.)</p>

CC BY-SA 3.0
2014-02-09T18:01:09.737Z
2014-02-09T18:16:49.557Z
2014-02-09T18:16:49.557Z
Walter
<p>No, no stars have an exactly spherical shape. The reason for this is that the centrifugal force of the star's rotation is much greater at the equator of the star than it is at the poles, for the simple reason that the rotational velocity is greater. This greater centrifugal force pushes the equator outwards, stretching the star into an oblate shape. This is called <a href="http://en.wikipedia.org/wiki/Gravity_darkening" rel="noreferrer">gravity darkening</a>.</p>

<p>Because we have only visually resolved the surfaces of a few other stars, it's not something that is commonly <em>directly</em> observed (though the effect can also be observed from stellar spectra). <a href="http://en.wikipedia.org/wiki/Regulus" rel="noreferrer">Regulus</a> is one star that has been <a href="http://adsabs.harvard.edu/abs/2007ASPC..361..425G" rel="noreferrer">observed as an oblate spheroid</a> spectrographically. The image below shows the star <a href="http://en.wikipedia.org/wiki/Altair" rel="noreferrer">Altair</a>, directly imaged using the CHANDRA space telescope. <a href="http://dept.astro.lsa.umich.edu/~monnier/Altair2007/altair2007.html" rel="noreferrer">Go here</a> for an animation!</p>

<p><img src="https://i.sstatic.net/5RaSB.jpg" alt="enter image description here"></p>

<p>Some stars are also non-spherical due to the effects of a nearby star in a close binary orbit. Much like how the Moon causes tides on Earth, two stars can stretch each other's surfaces. If they're very close to one another, as in the picture below, there can even be mass transfer between them (<a href="http://en.wikipedia.org/wiki/Common_envelope" rel="noreferrer">ref common envelope</a>).</p>

<p><img src="https://i.sstatic.net/fZVSy.png" alt="enter image description here"></p>

CC BY-SA 3.0
2016-11-21T13:43:26.847Z
Also of note worthy is Vega which is egg-like.  Unlike Regulus, Vega is a solo-star, not a multi-star system.  Therefore Regulus' shaped could be an effect of the companion stars on it.  http://futurism.com/5-weird-stars-found-galaxy/
MiscellaneousUser
CC BY-SA 3.0
2014-02-09T21:21:04.090Z
2014-02-09T21:21:04.090Z
Moriarty
<p>Planets (at least, some of them like Earth) aren't exactly spherical - but what about stars? </p>

<p>Is Sun perfectly spherical, for example? What may be the reasons if it isn't? What about other stars? </p>

CC BY-SA 3.0
2014-02-09T18:01:43.583Z
nothing real is perfectly spherical.
Walter
CC BY-SA 3.0
2014-02-09T19:53:06.413Z
@Walter the question is mostly dedicated to its reason in the aspect of stars.
Zoltán Schmidt
<star>
Do stars have exactly sphere shape?
Zoltán Schmidt
# Do stars have exactly sphere shape?

(Asked by: username_0 on 2014-02-09)

Planets (at least, some of them like Earth) aren't exactly spherical - but what about stars?

Is Sun perfectly spherical, for example? What may be the reasons if it isn't? What about other stars?

**Tags:** star
> **Comments:**
> **username_1**: nothing real is perfectly spherical.  
> **username_0**: @Walter the question is mostly dedicated to its reason in the aspect of stars.  

---

## 3 answers

### Answer by username_3 on 2014-02-09. Score: 10 | Accepted answer

No, no stars have an exactly spherical shape. The reason for this is that the centrifugal force of the star's rotation is much greater at the equator of the star than it is at the poles, for the simple reason that the rotational velocity is greater. This greater centrifugal force pushes the equator outwards, stretching the star into an oblate shape. This is called [gravity darkening](http://en.wikipedia.org/wiki/Gravity_darkening).

Because we have only visually resolved the surfaces of a few other stars, it's not something that is commonly *directly* observed (though the effect can also be observed from stellar spectra). [Regulus](http://en.wikipedia.org/wiki/Regulus) is one star that has been [observed as an oblate spheroid](http://adsabs.harvard.edu/abs/2007ASPC..361..425G) spectrographically. The image below shows the star [Altair](http://en.wikipedia.org/wiki/Altair), directly imaged using the CHANDRA space telescope. [Go here](http://dept.astro.lsa.umich.edu/~monnier/Altair2007/altair2007.html) for an animation!

![enter image description here](https://i.sstatic.net/5RaSB.jpg)

Some stars are also non-spherical due to the effects of a nearby star in a close binary orbit. Much like how the Moon causes tides on Earth, two stars can stretch each other's surfaces. If they're very close to one another, as in the picture below, there can even be mass transfer between them ([ref common envelope](http://en.wikipedia.org/wiki/Common_envelope)).

![enter image description here](https://i.sstatic.net/fZVSy.png)

> **Comments:**
> **username_4**: Also of note worthy is Vega which is egg-like.  Unlike Regulus, Vega is a solo-star, not a multi-star system.  Therefore Regulus' shaped could be an effect of the companion stars on it.  http://futurism.com/5-weird-stars-found-galaxy/  

---

### Answer by username_2 on 2014-02-09. Score: 4

As well as being oblate, like most large spinning bodies, there is a high degree of turbulence in any heated gaseous body, whether that be large gas planets, like Jupiter, or stars.

Have a look at this NASA photo of the sun as an example:

![enter image description here](https://i.sstatic.net/FoPBO.jpg)

You can see a wide range of non-spherical details.


---

### Answer by username_1 on 2014-02-09. Score: 2

**No** (1. All stars rotate to some degree and hence are slightly oblate. 2. stars have no surface like a rocky planet, what we see is the photosphere, i.e. the surface from which light escapes without being (much) absorbed or scattered. This surface, however, is constantly moving due to convection. 3. close binary stars are affected by their partner's tide.)


---

