Small back hole merging more massive body

[Gerinski]

Hi. Let's say we have a black hole of limited mass, say a few solar masses, and it encounters a much more massive object which is not collapsed into a black hole, say a very massive star, in principle it seems that some giant stars have been detected with masses over 100 solar masses.

So let's imagine that the small black hole meets such a very massive star, and that their combined mass will not produce a black hole of the sum of their masses.

What would happen if both bodies collide and merge? will the small back hole "return" to a non-black hole mass merging with the massive star? will it remain as a black hole residing into the large star and slowly feed on it, eventually eating up the very massive star and producing a very massive black hole with the sum of both their masses? will they remain as separate entities, the small black hole and the large star living together next to each other?

Tx

 

[mfb]

will it remain as a black hole residing into the large star and slowly feed on it, eventually eating up the very massive star and producing a very massive black hole with the sum of both their masses?

This.
If it happens in the very early universe, it leads to a quasi-star.

 

[phyzguy]

will it remain as a black hole residing into the large star and slowly feed on it, eventually eating up the very massive star and producing a very massive black hole with the sum of both their masses?

I agree with mfb that this is what will happen. The only thing I would add is to remove the word "slowly". Some of the mass of the star will be ejected in the form of jets and some will be incorporated into the black hole, but I believe that the time scale for all of this to happen is on the order of seconds.

 

[mfb]

Not even the initial merging happens in seconds. The quasistar can live for (up to) millions of years, radiation pressure cancels gravitational pressure.

 

[phyzguy]

Not even the initial merging happens in seconds. The quasistar can live for (up to) millions of years, radiation pressure cancels gravitational pressure.

The OP asked what happens when a black hole of a few solar masses collides with a massive star of 100 solar masses. You think the resultant object can last for millions of years? I doubt this. I will look for simulations of this type of event.

 

[phyzguy]

My answer was based on simulations like this one. This is a simulation of what happens when the core of a massive star (order 100 solar masses) collapses to form a black hole of a few solar masses. This results in a few solar mass black hole inside of a ~100 solar mass star, which is similar to the situation the OP asked about. Look at the resulting simulation. Part of the surrounding star is ejected, and part falls into the growing black hole, and the whole process takes less than 1 second. I think the collision of a few solar mass black hole with a ~100 solar mass star would have a similar time scale. How could it possibly last for millions of years?

 

[mfb]

This is a simulation of what happens when the core of a massive star (order 100 solar masses) collapses to form a black hole of a few solar masses.

That is a completely different process, the collapse happens while no black hole exists, and without anything else that would stop the collapse. The black hole is the result of the collapse, not vice versa.