<p>I doubt two black holes could form within a single star, but they might form from a <a href="https://en.wikipedia.org/wiki/Contact_binary" rel="nofollow">contact binary</a>. That's a pair of stars so close that they touch and share a single atmosphere. For the stars that made the black holes for the LIGO gravitational wave discovery, just consider two very massive stars that are touching or nearly touching. They would share a single gaseous envelope for an atmosphere. Each one separately formed a black hole when it died, and then their two black holes merged.</p>

CC BY-SA 3.0
2016-03-27T19:01:59.487Z
2016-03-27T19:01:59.487Z
RichS
<p>After the discovery of gravitational waves by LIGO last week the team behind the Fermi gamma-ray telescope released a <a href="http://arxiv.org/abs/1602.03920" rel="nofollow">paper</a> that showed a soft gamma ray burst was detected only 0.4s after the gravitational wave was detected at LIGO, and it was also located in the right area of the sky. This could be evidence of a gravitational wave source with a detected EM counterpart.</p>

<p>Ultimately though the Fermi group resist claiming a full discovery as no electromagnetic signature is expected form a binary black hole merger, but whats interesting is that I saw another <a href="http://arxiv.org/pdf/1602.04735v1.pdf" rel="nofollow">paper</a> today that claimed a GRB could be caused by a binary black hole merger inside a massive rapidly rotating star. </p>

<p>Is such a system realistic or even possible?</p>

CC BY-SA 3.0
2016-02-17T12:51:34.703Z
I suspect no definitive answer is possible...
ProfRob
CC BY-SA 3.0
2016-02-17T18:33:36.330Z
Maybe I'm misreading the article, but the article doesn't suggest binary black holes inside a massive rapidly rotating star, but that binary black holes could be the product of the death of a massive, rapidly rotating star.
userLTK
CC BY-SA 3.0
2016-02-17T21:29:43.090Z
What @userLTK said - the star collapsed into the black holes.
HDE 226868
CC BY-SA 3.0
2016-02-18T11:31:31.010Z
@userLTK Yes I think your right, it implies that the core of the star (not the whole star) collapses into two black holes, which is where I got confused but after such a violent process the core is probably all that is left anyway. Maybe I should change "exist" to "form" in the question.
Dean
<black-hole><astrophysics><rotation><gravitational-waves><gamma-ray-bursts>
Could a pair of binary black holes form within a star?
Dean
# Could a pair of binary black holes form within a star?

(Asked by: username_0 on 2016-02-17)

After the discovery of gravitational waves by LIGO last week the team behind the Fermi gamma-ray telescope released a [paper](http://arxiv.org/abs/1602.03920) that showed a soft gamma ray burst was detected only 0.4s after the gravitational wave was detected at LIGO, and it was also located in the right area of the sky. This could be evidence of a gravitational wave source with a detected EM counterpart.

Ultimately though the Fermi group resist claiming a full discovery as no electromagnetic signature is expected form a binary black hole merger, but whats interesting is that I saw another [paper](http://arxiv.org/pdf/1602.04735v1.pdf) today that claimed a GRB could be caused by a binary black hole merger inside a massive rapidly rotating star.

Is such a system realistic or even possible?

**Tags:** black-hole, astrophysics, rotation, gravitational-waves, gamma-ray-bursts

> **Comments:**
> **username_1**: I suspect no definitive answer is possible...  
> **username_2**: Maybe I'm misreading the article, but the article doesn't suggest binary black holes inside a massive rapidly rotating star, but that binary black holes could be the product of the death of a massive, rapidly rotating star.  
> **username_3**: What @username_2 said - the star collapsed into the black holes.  
> **username_0**: @username_2 Yes I think your right, it implies that the core of the star (not the whole star) collapses into two black holes, which is where I got confused but after such a violent process the core is probably all that is left anyway. Maybe I should change "exist" to "form" in the question.  

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## 1 answers

### Answer by username_4 on 2016-03-27. Score: 1

I doubt two black holes could form within a single star, but they might form from a [contact binary](https://en.wikipedia.org/wiki/Contact_binary). That's a pair of stars so close that they touch and share a single atmosphere. For the stars that made the black holes for the LIGO gravitational wave discovery, just consider two very massive stars that are touching or nearly touching. They would share a single gaseous envelope for an atmosphere. Each one separately formed a black hole when it died, and then their two black holes merged.


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