Ingassing of Hydrogen in the Interiors of Sub-Neptunes and Gas Giants

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The interiors of large planets such as Jupiter, Saturn, or Neptune are at very high temperatures and pressures. The behavior at the boundary between hydrogen-rich atmospheres and mineral-rich cores under these conditions is not well understood. This project will perform experiments on Earth using high-pressure and high-temperature conditions to determine how hydrogen interacts and is possibly absorbed into the materials of the core. The results will help answer questions about the interiors and history of giant planets. The project will share their results through education at the university level as well as through public outreach events at Arizona State University.The project will use diamond anvil cells to subject silicates and iron metal alloys in hydrogen media to pressures up to 100 GPa and temperatures put to 4,600 K. The resulting reactions will be analyzed using time-resolution X-ray diffraction. The data from these experiments will help answer these key questions: (1) Can hydrogen be ingassed to the interiors through chemical reactions? (2) If ingassed, in what type of chemical forms would H exist (water, metal alloys, or hydrides)? (3) Can H ingassing alter the mass-radius relations of planets? and (4) Can such reactions be affected by the metallization of dense liquid hydrogen and therefore be planet size dependent? The project includes an undergraduate research program. Teaching modules for calculating mass-radius relations of planets will be developed and shared as an open-source teaching resource in public code repositories. Public outreach presentations will be made and campus-wide outreach events at Arizona State University.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.