# Small back hole merging more massive body

• I
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

## Answers and Replies

mfb
Mentor
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
Mentor
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