What would volatile-rich planets like Pluto, Europa, Ganymede or Titan look like in a star system with a high C/O ratio and what would they be composed of? As water cannot form in carbon-rich systems because almost all the oxygen would bind with carbon making CO or CO2.

So what would take the place of the water? Or would they simply not form.

From the research I have done, it looks like that carbon bearing volatiles like carbon monoxide and methane would be more common but I have also seen (only on the ArcBuilder's PCL list) that ammonia would take the place of water in carbon-rich systems.


1 Answer 1


Water Ice (*Probably)

I've always imagined the formation of the solar system being: "Here's a group of gases - start clumping together and see what happens.". If this is all there is too it, your question should be pretty simple to answer:

I believe it would follow that hydro carbons would be more common, and water would be less common. Those bodies would have more methane, probably oceans of the stuff.

At a stretch, you may even get naturally occurring seas of methanol (Carbon monoxide + hydrogen + high temp + high pressure + one of many catalysts = methanol).

Equally as much of a stretch, replace carbon monoxide with nitrogen (and the choice of catalyst with a fickle temperature range), you get ammonia, however the strong triple-bond of nitrogen makes it a very slow reaction. To quote wikipedia: basically inert.. It would seem unlikely that you'll get a lot of ammonia.

Methane and Methanol would be my answer in this case.


Earth's protoplanetary disk was too hot to form water with the earth, and where that water came from is an open question - all the hyptopheses linked there require some form of bombardment. Maybe it came from outside the solar system, maybe it formed at the belt, and Jupiter chucked it at us, we don't know.

Research linked to from https://en.wikipedia.org/wiki/Interstellar_ice, suggests that up to 50% of the water in the solar system predates it. Tiny grains of amorphous water and methanol exist in the intersteller medium, apparently becoming crystalline in the presence of a star. These ice crystals would form into ice balls, and eventually become comets, which, during the late stages of solar system formation, bombard it with water.

Assuming this is where the solar systems water came from - These comets would contribute water to the solar system regardless of the oxygen / carbon ratio. You'd still get Ice in the far reaches of the solar system.


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