Summary: Gliese 581 c

I do not know if this is the right place to post

If rich in metal
-geology very active
-may be lava lakes
-atmosphere of C02 and N2
-clouds of wather, ice and sulfuric acid
-not habitable

If rich in silicates
-geology very active
-may be seas of supercritical wather
-atmosphere of C02 and N2
-clouds of wather, ice and sulfuric acid
-not habitable(?)

If rich in wather
-mantel of hot ice
-global ocean of wather
-atmosphere of N2
-clouds of wather and ice (reflective)
-habitable if the mantel of hot ice is on convection



tell me what you think about this summary

It should be the right place.

Well, I've some doubts about existence of hot ice. It's not like GJ 581 b which has roughly Neptune's mass and mass and pressure are enough to keep supercritic ice solid. Gj 581 c should be more like Venus, thus silicate rich, even CO₂ rich (thus high greenhouse effect) and stained by sulfuric and chloridric acid. Maybe, GJ581c could be "wetter" than Venus.

However, consider star GJ 581 seems showing slight residuals in radial velocity hinting a fourth planet, right in system's habitable zone.
Such exoplanet would have twice the Earth's mass and located at 0.113 AUs.

I said well that for a metalic or siliceous composition, the atmosphere
is rich in CO2 with clouds of sulphuric acid as Venus (on the contrary
I have never heard about HCL on Venus)

For the hot ice, its existence
is possible if on the base the planet is rich in water and that its
primordial oceans were very deep. I have to find the paper saying that
if the oceans of the Earth were a little deeper then there would be the
hot ice.

The possibility of existence of a planet e is very
interesting. I would really like to read a paper over.

A terrestrial planet in the kind of orbit that Gl581c is in would end up with a lot of tidally-generated activity. You'd probably end up with a thick carbon dioxide atmosphere from that activity, rather like Venus. (In fact, the atmosphere of Venus at the surface is above the critical point of carbon dioxide, so we could regard Venus as having a supercritical CO₂ ocean!)

Remember that water vapour is a greenhouse gas, so an "ice planet" would be a very hot one! If the planet is icy (water-rich), the likely situation is a supercritical "ocean" over a high pressure ice mantle. The atmosphere may well contain some free oxygen (due to photodissociation of water by starlight) as well as things like nitrogen, water vapour and carbon dioxide. You might get liquid water in the form of rain at the top of the atmosphere, particularly over the nightside, but it would not reach the surface. This might constitute a "habitable region" of sorts, insert argument about whether abiogenesis mid-air in raindrops is possible...