Thanks Gromsch for the data. FYI, you have a transcribing error in the mass for Dryooe Prou ZS-S b4-17 4 - there's an extra 0 in there which would be throwing your graphs off, probably that one that looked most out of place.
Anyway - for the Icy rings, I calculated a density (sort of). I worked out the area of the outer radius, subtracted the area of the inner radius and then calculated the mass divided by this area. For this "density", we're assuming all rings have the same width (and that width is "1"), but as we have no data on that, and no way to work it out it seems an OK assumption. This is the result:
Looking like a good chance that magic density is between 0.0280743 and 0.0323287. Obviously a limited data-set, but could it be that easy? Be interesting to see (or rather not see) if there are any non-icy invisible rings out there. The density threshold will be different - one of the visible rocky rings has a density of under 0.004.
This all might be completely wrong, but it might be a good starting point to collect more data.
Anyway - for the Icy rings, I calculated a density (sort of). I worked out the area of the outer radius, subtracted the area of the inner radius and then calculated the mass divided by this area. For this "density", we're assuming all rings have the same width (and that width is "1"), but as we have no data on that, and no way to work it out it seems an OK assumption. This is the result:
Body | visible? | type | density |
Hypoe Prau TF-O b51-21 4 | 0 | Icy | 0.0005443947298 |
Dryaa Pruae BG-X d1-5664 12 | 0 | Icy | 0.001406524217 |
Eorm Phyloi DU-A d431 B 5 | 0 | Icy | 0.003064110788 |
Dryooe Prou ZS-S b4-17 4 | 0 | Icy | 0.01929485133 |
Eol Prou XJ-Q d5-1268 A 4 | 0 | Icy | 0.02122193928 |
Eol Prou VD-J d9-113 A 8 | 0 | Icy | 0.02734660214 |
Phroea Hype CM-C d24 8 | 0 | Icy | 0.02807429529 |
Eol Prou QB-O c6-127 A 6 | 1 | Icy | 0.03232870923 |
Splierd UD-B d1 8 | 1 | Icy | 0.05639035931 |
LTT 16019 3 | 1 | Icy | 0.06522473864 |
Prooe Drye FH-J d10-68 6 | 1 | Icy | 0.09329658786 |
NGC 7822 Sector BQ-Y d12 A 3 | 1 | Icy | 0.1497549216 |
Looking like a good chance that magic density is between 0.0280743 and 0.0323287. Obviously a limited data-set, but could it be that easy? Be interesting to see (or rather not see) if there are any non-icy invisible rings out there. The density threshold will be different - one of the visible rocky rings has a density of under 0.004.
This all might be completely wrong, but it might be a good starting point to collect more data.