[1]sciencehabit shares a report from Science.org:

> From enabling life as we know it to greasing the geological machinery of plate tectonics, water can have a huge influence on a planet's behavior. But how do planets get their water? An infant world might be bombarded by icy comets and waterlogged asteroids, for instance, or it could form far enough from its host star that water can precipitate as ice. However, certain exoplanets pose a puzzle to astronomers: alien worlds that closely orbit their scorching home stars yet somehow appear to hold significant amounts of water.

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> A new series of laboratory experiments, [2]published today in Nature , has revealed a deceptively straightforward solution to this enigma: [3]These planets make their own water . Using diamond anvils and pulsed lasers, researchers managed to re-create the intense temperatures and pressures present at the boundary between these planets' hydrogen atmospheres and molten rocky cores. Water emerged as the minerals cooked within the hydrogen soup. Because this kind of geologic cauldron could theoretically boil and bubble for billions of years, the mechanism could even give hellishly hot planets bodies of water -- implying that ocean worlds, and the potentially habitable ones among them, may be more common than scientists already thought. "They can basically be their own water engines," says Quentin Williams, an experimental geochemist at the University of California Santa Cruz who was not involved with the new work.



[1] https://slashdot.org/~sciencehabit

[2] https://www.nature.com/articles/s41586-025-09630-7

[3] https://www.science.org/content/article/alien-worlds-may-be-able-make-their-own-water