I was reading into brown dwarf systems and I heard that most planets orbiting one would mostly be depleted of water and be carbon planets, though it never gave an answer as to why. Jupiter and it's moons are rich in water and water ice, and a brown dwarf is only a few times more massive, so why are their satellites/planets so different? Is it due to their formation method or something else?
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12$\begingroup$ Better with a citation to where this is claimed or discussed. $\endgroup$– ProfRobCommented Sep 24 at 20:26
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$\begingroup$ On page 23 of arxiv.org/pdf/1311.1228 it says that the inner regions of brown dwarf disks are drier than t tauri disks and the composition of rocky planets around brown dwarfs should include large amounts of carbon. $\endgroup$– snoCommented Sep 25 at 4:01
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To explain the high C/O and HCN/H$_2$O ratios in the inner region of brown dwarf circumstellar disks the authors of the article mentioned (arxiv.org/pdf/1311.1228) deduce that the icy planetesimals beyond the snow line are not migrating inwards around brown dwarfs. In larger planetary disks icy planetesimals migrate inward and supplement the water within the snow line. Migration is probably not effective in Brown Dwarf disks because the gas density is too low. They also speculate that the formation rate of icy planetesimals is more efficient in the smaller disks. The lines they measure indicate temperatures above 600 C so they are selectively measuring the chemistry only in the inner parts of disks.
Most of the oxygen in a disk binds with the plentiful amount of hydrogen so with less water there is less oxygen and a higher C/O ratio.
The Earth formed within the snow line where water remains gaseous in the planetary disk, so our water came from planetesimals or comets from beyond the snow line.
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$\begingroup$ arxiv.org/pdf/1311.1228 mentioned in the comments. $\endgroup$– eshayaCommented Sep 28 at 14:28