Systems with a Saturn at 5 AU or more c+ elemental mass fraction might have a lot more bodies like Ceres than our own. I would expect kuiper belt type zones around other stars to be filled with ice dwarves as well.

I've heard the theory in passing about a short lived isotope causing heating in some small bodies, but don't see how this can be supported based on the rarity of objects like Vesta. Why wouldn't the much larger Ceres have had the same conditions or other objects comparable in size to Vesta?

Pluto should be about 50:50 ice rock with a density of 2. Where do you get your 25:75 number from? All the big moons and Pluto besides the Luna sized triplets have a density of about 2. Europa, Luna, and Io vary from 3.0 to 3.6 being mostly rock with some metallic core. All three have experienced heating that caused water loss. The ice dwarf state if defined at > 25:75 water/rock ratio appears very likely past the solar snow line.

It's strange that Saturn's major moons have the lowest average density excluding Titan. Maybe Jupiter was at the snow line, but Saturn got the lake effect. It's the weirdest Moon of all, Saturn's Enceladus that makes me really dubious of the Pluto's too small to be a planet or of much interest crowd. We don't understand Enceladus and it's very interesting despite being near the size limit of even the original proposed definition of a planet. It may only be a moon, but we don't know it wouldn't be just as interesting and as big a potential habitat for life if it orbited the sun by itself. Scientists can not project an Io type gravitational flex on Enceladus based on its current orbit or realistic deviations yet it is currently very active. If a body like Enceladus can be such an enigma I have a real hard time lumping potentially similar objects with nearly prestine planetisimals.

You responded to my last two paragraphs. The first two were most relevant to previous discussions. How was your point about coorbital objects in nontraditional satellite orbits intended to impact my rough planet definition? Do you know if or why there is controversy over the definiiton of brown dwarf?

Regards,
Mark