How can a very cold gas giant be so compact and yet have the same mass as the sun? I have seen people suggest that massive stars will merge. Some of the largest stellar black hole mergers ever have occurred when a star has been hit by a much larger black hole. This was the case with NGC 4955. The original star was around 200 light years away, not 500. Larger than the sun, but still only 100,000 times more massive. That is a great coincidence, and one that a lot of people have missed.
Anyway, it wasn’t until 2012 that one of these guys came together. He formed a singularity, about ten times the size of the sun, with the heat coming from the surrounding stars. It was super dense and super hot. In fact, the inner part of the singularity is so hot that it consumes hydrogen that is currently passing through, and vaporizes it into a form that is now reaching the outer edges. I have made a chart showing the properties of this region that seems to indicate how massive it is today:
The inner part was not as dense as the outer part, so the star has a lot of leftover mass and a lot less atmosphere. The interior seems to be a lot more dense than the outer regions, as the two regions actually have the same density, but it is not visible in the graph. So, at some point, either the black hole was not very massive because it is smaller, or the star was too small for the new black hole to form a massive enough singularity, before being captured to the other end.
As the stars migrate away from the binary, the inner part becomes increasingly hot and dense. It stays hot and dense for millions and billions of years. In this stage, if you can imagine a giant version of the ocean at the bottom of a very intense deep-sea trench, then this is what we are seeing. It moves down the trench like rock being pushed down from above, and as it gets to the bottom of the trench, it cools but only reaches a surface temperature of about 1500 K. Even though the temperature is cool as a rock, it has a lot of friction and would rapidly collapse, so when it becomes to the surface, it rapidly cools as well. This is the only way a star can become quite as hot as it is today, while it is still at the outer regions.
The new black hole, however, is even denser than the inner part. It is over 4000 times the mass of our sun. The surface temperature is around 1200 K. The entire area of this black hole is moving at 20,000 mph! At some point, this new black hole could have collapsed into all of the other stars, and the process was almost over.
There is still a matter of seconds before the gas giant had enough to form another star. It would have had to pass through this new black hole to the other side in less than half a second. If the gas giant moved fast enough, it could still hit the black hole and keep moving like the rock on top of the trench. This is very, very impressive. Imagine the rock smashing through a concrete wall at 30 mph. That is what you are going to get if you go through a black hole in a matter of seconds if this black hole is moving fast enough.
The new black hole could be much much, much bigger than LB1. If it were a hundred times the mass of the sun, then the hole should have some amount of disk around it that was pulled in by it and the gas giant. Either way, the disk is probably expanding, which is good, as this new black hole is sucking in more matter. This gas giant’s mass will need to be significantly less than its own to allow this to happen.
It doesn’t seem like a bad thing for the black hole to die. It is certainly not very hot or dense, so this is a way for it to pass away after it consumes much less mass. The black hole’s surface is made of very thick hydrogen gas in the inner part. It could be a lot more dense than the outer part of the hole, but is so close to the black hole, at this point, that I can’t really see any reason to think it would be less dense. This one is very close to dying, so in many ways it’s a good thing for LB1, because it ensures it doesn’t pass too far away from the black hole to create a new black hole larger than LB1. But the process does not end with a gas giant that is getting sucked away. It can continue on, becoming a red supergiant black hole that can contain a huge solar mass