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For my current Eclipse Phase campaign/Fan Fiction I set up a "habitable" Gas Giant, by habitable I mean, that there is a layer in its atmosphere, where 1 bar of pressure and a temperature of ca. 283 K more or less coincide.
(What can I say, I love my cloud cities.)
The surface would, of course, still a metallic hydrogen ocean and a very unhealthy place to be.
Is there anything that would rule out this set up? Anyone would like to take an educated guess at the atmospheric composition or distance from its star? One assumes that a "hot jupiter" would be more likely for this?
I provisionally named the place Lapis-Lazuli and have a lot of fluff written out, going on about its aquamarine/ultramarine cloudscapes, fading to jade. I'm kind of fond of it and would like to keep if, but the methane ice, which give the blue coloration has a melting point of 90 K. Would the gas also work? If not, is there some other kind of chemical composite, which would have the same visual effect?
2.1 To clarify, when I say aquamarine cloudscapes, I would like to have a blue sky from the Rayleigh-scattering (Is there any reason that should be different for an atmosphere of, say, primarily Hydrogen, Helium, Methane and Water Vapor?) and the cloud decks itself.
Is there any particular reason, why a gas giant could not have a noticeable partial oxygen pressure?