Rings structure and distance from star.Is there any rule?

[danielj]

I was thinking in create imaginary rings,manipulating png images.ACTUALLY I am creating some with Adobe Photoshop,but I would like,if possible,to know some scientific information.
In our solar system,Saturn is the only ring easily visible,made of ice mainly and I should call it a "solid" ring(well scructured and the distance for the Sun is about 10 AU.Well,jupiter,at 5.2 AU,have a thinner and much less visible system of rings and I should call it "fuzzy".But Uranus and Neptune are much far away,but the rings are between "fuzzy" and "solid".Do you know if is it a rule to,how far from a star(and how near),for example,a ice ring could form?Should I expect a more "rocky" and darker ring near a star,in the position equivalent to Eath and Mars orbit?Or is it entirely aleatory?
And what about the colour of the rings?Is it possible to have any ring color?And does it is related,in some way,to the distance of the star?
I?ll apreciate your help



A

[Evil Dr Ganymede]

Ring structure and appearance seems to be down to what created them. AFAIK Jupiter's ring seems to be formed by dust albated from Almalthea, Adrastea and Metis. Saturn's are probably formed by a completely destroyed small satellite or two. Dunno about the Uranian or Neptunian rings - possibly their similar in origin on Jupiter's?

If you could get any rings around planets within the frost line (ie where you get terrestrial planets) then they'd be dark and rocky. Icy rings would only be possible around more distant planets where it's colder.

(and you win the award for the first use I've ever seen of the word "aleatory" )

They're all within the roche limit of the planet though, which is about 2.5 radii. Any rings beyond that would be able to coalesce into satellites eventually. (though for more massive primaries like superjovians or Brown dwarfs, the roche limit is actually further out, up to about 6 radii!)

[Michael Kilderry]

I've made up my own fictional planet, called Jovalera. It is a terrestrial planet with a blue ring around it, way outside the roche limit. What keeps this ring from gathering to form a moon is the presence of another large, nearby moon, called Marbles.

Michael