Hi Mark

Brown dwarfs, like stars, are believed to form via direct collapse within molecular clouds, and there seems to be no natural lower mass limit. As a result the free-floating objects in young clusters pose a real puzzle - some seem smaller than the 13 Jupiter mass limit, thus could be "planets", but they (probably) formed like their larger siblings. Yet there's no sensible way of deciding if they formed as planets do and escaped their parent stars, or collapsed direct from their birth clouds.

As for the rest of what you said and quoted in your first post I agree pretty much. Mike Brown's ideas are clear enough, though a bit inconsistent with his earlier "historical planet" stance.

Ceres has a density of 2.077 or so, like Pluto. Thus I was guessing.

Adam