Story perspectives

Sub-Neptune Planets May Evolve into Water-Rich Hycean Worlds

10/30/2025

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Summary

Story summary

Sub-Neptune planets' rocky cores can produce water via hydrogen-silicate melt reactions, with production reaching 38–56 mol% under specific conditions.
The Mg:Si ratio influences water production, and higher pressures enhance solubility and reaction efficiency.
Efficient convective mixing in these planets may create a water-rich deep envelope as the planet cools.
If a hydrogen-rich atmosphere is retained, these planets could evolve into hycean worlds with a water-rich layer above the core.

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Story summary

Sub-Neptune planets' rocky cores can produce water via hydrogen-silicate melt reactions, with production reaching 38–56 mol% under specific conditions.
The Mg:Si ratio influences water production, and higher pressures enhance solubility and reaction efficiency.
Efficient convective mixing in these planets may create a water-rich deep envelope as the planet cools.
If a hydrogen-rich atmosphere is retained, these planets could evolve into hycean worlds with a water-rich layer above the core.