Are supermassive black holes just big stars?

In summary: However, it is possible that they could have formed from the merging of multiple early stars or through other processes. There is still much to be discovered and understood about the formation of supermassive black holes.
  • #1
Singlecoil
1
0
Simple enough question. I know there are two types of black holes; the type formed after a star collapses in a supernova and the supermassive variety like the one at the center of the milky way.
If a star continued to grow by swallowing up other stars and solar systems is it possible that at a certain point its gravitational field would become so strong that light and heat could no longer escape? It would be a tipping point. Prior to reaching that mass it would be a bright star, but as it continued to grow it would start to dim as some wavelengths of the electromagnetic spectrum could no longer escape the massive star's gravitational field. Eventually it would reach such a size that it would appear dark to an observer, but in reality it is a bright and hot star that can no longer be conventionally detected.
 
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  • #2
(Not absolutely sure.) As long as the star is shining its volume would be too big to become a black hole. Once it runs out of fuel then things would happen.
 
  • #3
Seems likely that if you have enough mass in a small volume to keep photons from escaping, you have enough mass in a small volume that it will collapse into a black hole.

Or it may be that a BH has to already BE there to keep photons from escaping.
 
  • #4
phinds said:
Seems likely that if you have enough mass in a small volume to keep photons from escaping, you have enough mass in a small volume that it will collapse into a black hole.

Indeed, this is a tautology by definition :)
 
  • #5
Singlecoil said:
Prior to reaching that mass it would be a bright star, but as it continued to grow it would start to dim as some wavelengths of the electromagnetic spectrum could no longer escape the massive star's gravitational field.
All wavelengths of light travel at the same speed, if the gravity is enough to stop one then it can stop all.
 
  • #6
I don't believe this is possible. Wouldn't an existing star simply burn more fuel, resisting collapse?
 
  • #7
Drakkith said:
I don't believe this is possible. Wouldn't an existing star simply burn more fuel, resisting collapse?

If that were true, how would ANY BH ever form? I think I must be missing something about what you are saying.
 
  • #8
phinds said:
If that were true, how would ANY BH ever form? I think I must be missing something about what you are saying.

I'm not saying that it wouldn't EVER turn into a black hole, only that it wouldn't be a black hole until it runs out of fuel.
 
  • #9
The Jeans mass limits the 'birth' mass of stars [which varies for Pop 1, II and III stars]. The mass limit for coalescence of stars is not well known. Stellar collisions are so extraordinarily rare in the univerve we have insufficient observational data to model the upper limit for these events. One thing, however, is well established, enormously massive stars simply do not live long enough to accrete a large amount of additional mass. Stars more than 100 solar masses only live for tens of millions of years, as compared to the sun, which has a life expectancy of around ten billion years.
 
  • #10
Drakkith said:
I'm not saying that it wouldn't EVER turn into a black hole, only that it wouldn't be a black hole until it runs out of fuel.

Ah, I KNEW there was something I wasn't connecting the dots with. Thanks.
 
  • #11
Hello all,

As many of you have seen a few of my posts you will know I am not overly speculative, so I am in no way promoting this as a theory just want to know if anything along these lines has been pursued before:

I have read somewhere that the early U may have had enormous stars, in orders of magnitude larger than current stars, would it be possible that the SMBH's at the center of each galaxy formed from these primordial massive stars? Or would we see evidence of this in the most distant galaxies? Are there any predictions for what massive objects formed the SMBH's or are they considered to merely have grown due to being "fed" stellar material for a few billion years?

Any information is appreciated.
 
  • #12
Cosmo Novice said:
Hello all,

As many of you have seen a few of my posts you will know I am not overly speculative, so I am in no way promoting this as a theory just want to know if anything along these lines has been pursued before:

I have read somewhere that the early U may have had enormous stars, in orders of magnitude larger than current stars, would it be possible that the SMBH's at the center of each galaxy formed from these primordial massive stars? Or would we see evidence of this in the most distant galaxies? Are there any predictions for what massive objects formed the SMBH's or are they considered to merely have grown due to being "fed" stellar material for a few billion years?

Any information is appreciated.
The early stars were (order of magnitude) around 100 solar masses.

Black holes at galactic centers are of the order of millions to billions of solar masses. It seems unlikely that they could form from early stars without accumulating a lot more material.
 

1. What is a supermassive black hole?

A supermassive black hole is a type of black hole that is incredibly large and has a mass equivalent to billions of suns. They are found at the center of most galaxies, including our own Milky Way.

2. How are supermassive black holes different from regular black holes?

Supermassive black holes differ from regular black holes in terms of size and mass. While regular black holes are formed from the death of a star and have a mass of a few times that of our sun, supermassive black holes are much larger and have a mass equivalent to billions of suns.

3. Are supermassive black holes just big stars?

No, supermassive black holes and stars are two completely different objects. While stars are made up of mostly hydrogen and helium and produce energy through nuclear fusion, black holes are incredibly dense objects with a strong gravitational pull that can even trap light.

4. How do supermassive black holes form?

The exact process of how supermassive black holes form is still not fully understood. However, it is believed that they can form through the merging of smaller black holes, the collapse of a large gas cloud, or the direct collapse of a massive star.

5. Do supermassive black holes pose a threat to Earth?

No, supermassive black holes are located at the center of galaxies and are incredibly far from Earth. Their immense gravitational pull can only affect objects that are very close to them, so there is no need to worry about them posing a threat to our planet.

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