Experiments reveal extreme water generation during planet formation

"The most abundant type of planet discovered in the Galaxy has no analogue in our Solar System and is believed to consist of a rocky interior with an overlying thick H2 dominated envelope. Models have predicted that the reaction between the atmospheric hydrogen and the underlying magma ocean can lead to the production of significant amounts of water. The models suffer however from the current lack of experimental data on the reaction between hydrogen and silicate melt at high pressures and temperatures."

"Laser heating diamond anvil cell experiments were conducted between 16 and 60 GPa at temperatures above 4000 K. We find that copious amounts of hydrogen dissolve into the silicate melt with a large dependence on temperature rather than pressure. We also find that the reduction of iron oxide leads to the production of significant amounts of water along with the formation of iron-enriched blebs."

The most abundant type of planet in the Galaxy consists of a rocky interior overlain by a thick H2-dominated envelope. Previous models predicted that atmospheric hydrogen reacting with underlying magma oceans can generate substantial water but lacked experimental constraints at relevant pressures and temperatures. Laser-heated diamond anvil cell experiments at 16–60 GPa and temperatures above 4000 K reveal that hydrogen dissolves copiously into silicate melts with solubility controlled strongly by temperature rather than pressure. Hydrogen-driven reduction of iron oxide produces significant water and yields iron-enriched blebs. These processes imply widespread water production that will affect planetary interior chemistry, structure, and atmospheric composition.

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