<p>For the first part of your question: A real black hole is formed from a collapsing start is likely to have angular momentum.  In theory a non-spinning black hole could be formed by collapse of a non-rotating star.  In theory, you could potentially also realize a non-rotating black hole if angular momentum were extracted from a rotating black hole via the Penrose process.</p>

<p><a href="https://en.wikipedia.org/wiki/Penrose_process" rel="nofollow">https://en.wikipedia.org/wiki/Penrose_process</a></p>

<p>For the second part of your question, I think it's not quite clear what you mean.  The best that I can understand your question, I would say that matter is "absorbed" the same, although the path taken into the black hole may depend on its spin.</p>

CC BY-SA 3.0
2016-09-19T01:54:44.203Z
This begs the question, if we find a non-rotating black hole in the future, was it more likely created by natural processes or aliens extracting the energy via Penrose process? :)
joseph.hainline
CC BY-SA 3.0
2017-01-06T20:28:35.967Z
I wonder if a kugelblitz would be non rotating.
Howard Miller
CC BY-SA 3.0
2015-08-24T19:27:01.247Z
2015-08-24T19:27:01.247Z
Brick
<p>All stars have <em>some</em> angular momentum. Conservation of angular momentum when the core of a star collapses means that it is very likely that most black holes are rapidly rotating, just as newly-born neutron stars are observed to be extremely fast-rotating.</p>

<p>Even if one were to have a star with a non-rotating core as it collapsed, the subsequent accretion of material with angular momentum would give the black hole that angular momentum.</p>

<p>Non-spinning black holes are a theoretical ideal that is unlikely to be found in nature.</p>

<p>The details of the accretion of material onto a black hole are complex and still the subject of theoretical and observational research. But yes, the details of accretion in spacetime governed by the <a href="https://en.wikipedia.org/wiki/Kerr_metric" rel="noreferrer">Kerr metric</a> appropriate for rotating black holes will differ from those of a non-rotating <a href="https://en.wikipedia.org/wiki/Schwarzschild_metric" rel="noreferrer">Schwarzschild</a> black hole. Kerr black holes have an "ergosphere", outside their event horizons, where material is force to co-rotate with the black hole.  </p>

CC BY-SA 3.0
2015-08-24T13:59:39.930Z
Sounds like an accretion disc inside ergosphere would act to spin up a non-rotating black hole.
Wayfaring Stranger
CC BY-SA 3.0
2015-08-24T14:16:46.417Z
@WayfaringStranger A non-rotating black hole doesn't have an ergosphere.
ProfRob
CC BY-SA 3.0
2015-08-24T14:19:48.910Z
Now I *think*, of course not. Seems an accretion disk might still spin the thing up, even wo material necessarily crossing event horizon.
Wayfaring Stranger
CC BY-SA 3.0
2015-08-24T13:28:35.663Z
2015-08-24T13:28:35.663Z
ProfRob
<ol>
<li>How are non-rotating black holes formed?</li>
</ol>

<p>I guess that non-rotating black holes are formed from non-rotating stars but I couldn't find any proof that such a star exists on the internet. If this is true can you also put up an example of such a star?</p>

<ol start="2">
<li>Does the matter absorption of a non-rotating black hole differ from a rotating black hole?</li>
</ol>

CC BY-SA 3.0
2015-08-24T18:40:55.807Z
Also, one question per question please...
Lightness Races in Orbit
CC BY-SA 3.0
2015-08-26T20:10:35.987Z
@Axl: Sometimes, when they are conjunct parts of the same question, but I don't see that this is really the case here? Granted, I'm no astrophysicist :)
Lightness Races in Orbit
CC BY-SA 3.0
2015-08-26T23:27:46.960Z
@Axl alright noted for the future, thanks guys!
CipherBot
<black-hole>
How is a non-rotating black hole created
CipherBot
# How is a non-rotating black hole created

(Asked by: username_0 on 2015-08-24)

1. How are non-rotating black holes formed?

I guess that non-rotating black holes are formed from non-rotating stars but I couldn't find any proof that such a star exists on the internet. If this is true can you also put up an example of such a star?

2. Does the matter absorption of a non-rotating black hole differ from a rotating black hole?

**Tags:** black-hole

> **Comments:**
> **username_1**: Also, one question per question please...  
> **username_1**: @Axl: Sometimes, when they are conjunct parts of the same question, but I don't see that this is really the case here? Granted, I'm no astrophysicist :)  
> **username_0**: @Axl alright noted for the future, thanks guys!  

---

## 2 answers

### Answer by username_5 on 2015-08-24. Score: 6 | Accepted answer

All stars have *some* angular momentum. Conservation of angular momentum when the core of a star collapses means that it is very likely that most black holes are rapidly rotating, just as newly-born neutron stars are observed to be extremely fast-rotating.

Even if one were to have a star with a non-rotating core as it collapsed, the subsequent accretion of material with angular momentum would give the black hole that angular momentum.

Non-spinning black holes are a theoretical ideal that is unlikely to be found in nature.

The details of the accretion of material onto a black hole are complex and still the subject of theoretical and observational research. But yes, the details of accretion in spacetime governed by the [Kerr metric](https://en.wikipedia.org/wiki/Kerr_metric) appropriate for rotating black holes will differ from those of a non-rotating [Schwarzschild](https://en.wikipedia.org/wiki/Schwarzschild_metric) black hole. Kerr black holes have an "ergosphere", outside their event horizons, where material is force to co-rotate with the black hole.

> **Comments:**
> **username_6**: Sounds like an accretion disc inside ergosphere would act to spin up a non-rotating black hole.  
> **username_5**: @username_6 A non-rotating black hole doesn't have an ergosphere.  
> **username_6**: Now I *think*, of course not. Seems an accretion disk might still spin the thing up, even wo material necessarily crossing event horizon.  

---

### Answer by username_2 on 2015-08-24. Score: 3

For the first part of your question: A real black hole is formed from a collapsing start is likely to have angular momentum. In theory a non-spinning black hole could be formed by collapse of a non-rotating star. In theory, you could potentially also realize a non-rotating black hole if angular momentum were extracted from a rotating black hole via the Penrose process.

<https://en.wikipedia.org/wiki/Penrose_process>

For the second part of your question, I think it's not quite clear what you mean. The best that I can understand your question, I would say that matter is "absorbed" the same, although the path taken into the black hole may depend on its spin.

> **Comments:**
> **username_3**: This begs the question, if we find a non-rotating black hole in the future, was it more likely created by natural processes or aliens extracting the energy via Penrose process? :)  
> **username_4**: I wonder if a kugelblitz would be non rotating.  

---

