Among the different types of Super-Earths, one type can be envisaged: a "pontic" planet (after the Greek elemental god of sea, Pontus, also a region bordering the Black Sea). Pontic planets would consist of a rocky core, hot ices, a global ocean and a thick hydrogen/helium atmosphere. A kind of small Uranus/Neptune, with the ocean being liquid instead of supercritical, and in everlasting darkness. They would be a sub-category of oceanic planets.
SDC ( http://www.space.com/scienceastronomy/0 ... phere.html ) reports that exoplanet GJ 1214b could have such a structure. A reservation though, it would lie very close to its star, and so its potential ocean would be more likely to be supercritical as in Uranus or Neptune. It is nonetheless interesting imho that they have found such a planet with about 5 Earth masses. If it lied further from its star, the stellar heat flux would not add to the internal heat... If such planets are common, then this is great news. The main "interest" of pontic planets lies indeed in their capability to support by their own a liquid ocean with a free surface (as opposed to a Europa-like subglacial ocean that is capped by an iceshelf), thanks to internal heat combined with the thermal insulation brought by the thick atmosphere. They would extend the notion of habitats very far from stars, and even to free-floating planets!
SDC ( http://www.space.com/scienceastronomy/0 ... phere.html ) reports that exoplanet GJ 1214b could have such a structure. A reservation though, it would lie very close to its star, and so its potential ocean would be more likely to be supercritical as in Uranus or Neptune. It is nonetheless interesting imho that they have found such a planet with about 5 Earth masses. If it lied further from its star, the stellar heat flux would not add to the internal heat... If such planets are common, then this is great news. The main "interest" of pontic planets lies indeed in their capability to support by their own a liquid ocean with a free surface (as opposed to a Europa-like subglacial ocean that is capped by an iceshelf), thanks to internal heat combined with the thermal insulation brought by the thick atmosphere. They would extend the notion of habitats very far from stars, and even to free-floating planets!
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