Elemental sodium and potassium, which have very low boiling points in comparison with rocks, do not rain out but would instead stay in the atmosphere,
where they would form high gas clouds buffeted by the stellar wind from COROT-7.
I think this is not possible at such temperatures. What are your ideas? m1tanker78 - 23-12-2012 at 06:12
I imagine the dense 'rock' vapors would displace the less dense Na vapor. If the planet's atmosphere is viewed like a fractionating column then Na and
K vapors would certainly be among the 'highest clouds' and wouldn't condense at that temperature. The planet exerts ~5x Earth's gravity as well so...
I don't know about the plausibility of 'elemental' Na and K, though. Maybe they exist as transients in some sort of cycle between the sunny side and
dark side??
TankEndimion17 - 23-12-2012 at 08:50
There are traces of elemental alkali metals everywhere, that's obvious. We have those things trapped in minerals exposed to ionizing ratiation, where
they contribute to the discoloration of mineral specimens. Our exosphere must have minute amounts of such atoms, though ions are prevalent.
But real clouds would obviously require seriously high ground temperatures. I'm not surprised. Extremely high temperature, reductive atmosphere,
horrific radiation from the nearby star...
I remember reading about early hypotheses regarding Earth formation in one book. Elemental sodium was mentioned. There'd hardly be any chance for
rivers and puddles of it, but high clouds of partially ionized sodium? I see no obstacles.
Perhaps Earth also once had such tenuous alkali mists high above.Eddygp - 23-12-2012 at 10:06
Very plausible, but only if a very reductive atmosphere, as Endimion said, is also present. Alkali metals would (especially at that temperature) react
with anything nearby. However, it is of course possible.12AX7 - 23-12-2012 at 17:57
Most likely they're detecting ionized alkali molecules, such as atomic Na (a familiar bright orange!), diatomics (would be a sign of elemental alkali)
or salts (such as Na-Cl, the gaseous molecule).
The universe does tend to have a reducing atmosphere on the whole. Rock, as such, is a mixture, somewhere near stoichiometric, of silicon dioxide
with other stuff (most commonly aluminum, alkaline earth, and iron, oxides). Everything else is either metallic (mostly iron, nickel, and probably
some silicon), or carbon (a number of carbon-rich bodies have been detected, which given their approximate size, would probably be somewhere from
diamond (planetoid) to electron degenerate (white dwarfs). As we know, alkali metals can be synthesized from many reducing agents, thanks to their
volatility -- calcium, magnesium, aluminum, silicon and carbon for example. On such a world, magnesium, calcium and silicon would probably keep
oxygen locked up, while everything else kind of dissolves in the iron, or floats on it (carbon, and various carbides, might form a crust, for
instance).
