Exoplanet Discoveries and Updates

[The Astronomer]

Er. Actually we have:

a) An entire page devoted to super-terrestrial worlds that dates back to 2011 - LINK

b) Panthalassa (LINK), which is a pretty wet place (article written in 2008) and IIRC is also an example of the PanThalassic Type world - LINK (article written in 2008).

Is there something distinctly different about super-Earths and water worlds that clearly makes them not examples of what is described above? At the least, I think it's an oversimplification (if not flat out incorrect) to say we have nothing like these in the setting.

I'm less sure about sub-Neptunes, being in the setting earlier - that would be a Steve question.

Todd

Hmm...oh right, forgot to tell you this: Perhaps most of these 'ocean worlds' described in the article wouldn't have liquid oceans at all - they circle their star way too close for water to be liquid - just high volatile fraction (like >1% or even >10%. Earth, for example, has 0.02% of its mass as water). I know we know superterrestrials are possible, but not their true abundance until not many years ago, hence the rarity of them if you check every described system. I don't think OA has dived into these very common hot water worlds' properties much yet. The concept of liquid water ocean worlds is a lot older.

According to current research, liquid water ocean worlds seem to have a lot of issues with stability, and most would probably rather rapidly end up as either as a Europan (ice increases albedo, world cools down, increases ice, positive feedbacks) or a PelaCytherean (no effective, climate-responsive carbon sink).