The Inevitability of Rings....

[Dollan]

Given that every Jovian world in our system has rings of one type or another, would it be a logical assumption to say that at least most gas giants around other stars have rings as well? Would having rings be an inevitable consequence to being a gas giant?

I realize that we can't say with absolute certainty one way or another, but I'm interested your opinions.

...John...

[Michael Kilderry]

If you think about it though, every planet in our solar system has got some specks of dust floating around it however inconspicuous those specks may be. In a way, all the geostationary satellites around Earth form some sort of a ring as well, it might be just what you'd actually call a ring that makes the difference.

Michael Kilderry

[Evil Dr Ganymede]

Given that every Jovian world in our system has rings of one type or another, would it be a logical assumption to say that at least most gas giants around other stars have rings as well? Would having rings be an inevitable consequence to being a gas giant?

I realize that we can't say with absolute certainty one way or another, but I'm interested your opinions.

...John...

I'd say that it looks like it's rare for a jovian NOT to have rings. However, I think it's a lot more likely that jovians that are far from their primary star can retain rings - hot jupiters won't have them (they wouldn't be stable due to tides and temperature) and jovians within the snow line probably won't have them either for similar reasons.

Jupiter's ring seems to be maintained by material knocked off Amalthea and Metis and Adrastea. Not sure if Uranus' and Neptune's are maintained in a similar manner, but it seems that close asteroidal satellites have some role in maintaining them. Saturn's rings may be an entirely different kettle of fish though - given that we have four jovians and only one has a spectacular system, maybe a saturn-like ring system is rare.

[Dollan]

I'd say that it looks like it's rare for a jovian NOT to have rings. However, I think it's a lot more likely that jovians that are far from their primary star can retain rings - hot jupiters won't have them (they wouldn't be stable due to tides and temperature) and jovians within the snow line probably won't have them either for similar reasons.

Would the same be said for large (or even small) moons, then?

Jupiter's ring seems to be maintained by material knocked off Amalthea and Metis and Adrastea. Not sure if Uranus' and Neptune's are maintained in a similar manner, but it seems that close asteroidal satellites have some role in maintaining them. Saturn's rings may be an entirely different kettle of fish though - given that we have four jovians and only one has a spectacular system, maybe a saturn-like ring system is rare.

As far as Jupiter goes, what does Io have to do with the rings, anything? If material falls inward to coat Amalthea, wouldn't it also contribute to the ring system?

And Saturn... is the old thought that we are lucky to be seeing the rings at all still valid? I remember reading somewhere that it had been speculated that the rings might have a life time of about 5 million years, a pretty small geological window.

Of course, if there is some other mechanism aside from a shattered satellite which made the rings, then we need to account for how they are sufficiently replenished.

...John...

[ajtribick]

Further questions - while I can see how rings around hot Jupiters would be rare because of stability, surely within the snowline rocky ring systems (as opposed to icy) wouldn't be too rare? Also could material removed from the atmospheres of hot Jupiters (e.g. at HD 209458) form a ring system of sorts?

Another possibility: Brown dwarf rings - given that brown dwarfs have large Roche limits because of their high density brown dwarf rings could be a likely possibility, which raises the question of what happens when a brown dwarf ring system (which could be icy because there is not much heat from the brown dwarf) gets hit by a flare (which apparently can happen on brown dwarfs).