Jovian Moons: Is a Small Jovian a Moon of a Larger One?

[FtlIsAwesome]

My guess is that a small jovian can be a moon of a much larger jovian. Is this likely, and how would we detect it?

Just something I've never seen before. It seems that the assumption is that all moons of jovian planets are terrestrial.

Also possible are jovian binary planets, but I'm talking about where it is clear that one jovian is a moon of another.Thoughts?

 

[qraal]

My guess is that a small jovian can be a moon of a much larger jovian. Is this likely, and how would we detect it?

Just something I've never seen before. It seems that the assumption is that all moons of jovian planets are terrestrial.

Also possible are jovian binary planets, but I'm talking about where it is clear that one jovian is a moon of another.


Thoughts?

Trojan planet captured from a common orbit maybe? The lesser planet has to mass less than ~1/25 (IIRC) the larger planet to be in a stable Trojan orbit. Any more and their mutual attraction becomes just too much perturbation for the arrangement to be stable and they end up on "walking orbits" that ultimately interact. A super-jovian and a Neptune would work just nicely, so long as enough energy can be dissipated during their close encounter for capture.

Plus there's no reason why jovians can't orbit brown dwarfs. Some super-jovians might be runtish brown dwarfs that migrated inwards.