> Gas physics suggests you shouldn't be able to make objects with the mass of Jupiter on their own<p>This is new to me. I always imagined that on the way to star formation the coalescing gas would start as a small central mass and grow larger and larger, passing through a Jupiter-mass stage and eventually igniting. I also imagined that the process could involve several small central masses which would variously end up as binary/ternary/++ star systems and all manner of brown dwarves/planets/debris in orbit around the center. And I <i>also</i> imagined that this process would stop at whatever point the gas supply ran out.<p>So in my mind, a pair of Jupiters would be a failed binary star system that didn’t quite have enough mass to achieve ignition as a pair of stars.<p>But maybe I’m missing a gas-physics reason why it couldn’t happen like this.
The pairs really does sound strange. If they found one pair, that would be odd. Two pairs? Huh, is there a pattern? But five plus pairs? I can't wait for the theorists to explain how these are so common.
The confusion about 'pairs' is because it takes an interaction with another object to eject something from an orbit. (and as mentioned in the article it's not clear how these could form on their own). So how these would form is not clear, we don't see binaries of gas giants orbiting stars, but to be ejected they would have to somehow have been 2 gas giants interacting with a third mass (and not the star they are orbiting) to eject the pair.<p>Pairs of objects can't couple like this if they randomly meet in space because they would always be on a hyperbolic trajectory relative to each other unless they had a mechanism to bleed energy, which generally they do not outside of a stellar disk.<p>I guess my hypothesis is that these gas giants were ejected from the system they formed in, but rather than being merely ejected they also collided with something which ripped them apart. Imagine if the collision which created the moon also ejected the earth from orbit, like that.
<a href="https://arxiv.org/abs/2310.01231" rel="nofollow noreferrer">https://arxiv.org/abs/2310.01231</a> (<i>"Jupiter Mass Binary Objects in the Trapezium Cluster"</i>)
I remember reading many years ago that the Orion Nebula could be expected to full of loose planets that have ejected by newly formed solar-systems as they settle down. It didn't mention anything about binary planets, though.