Building a Wet Planet from Dry Materials

Zoom Link
for Colloquium 10/31/2023 3:00pm PST

Please email for zoom presentation password

Presented by Dan Shim Professor, School of Earth and Space Exploration, Arizona State University

Abstract: It has been believed that water-rich planets are formed outside the snow line. However, the discovery of many close-in orbiting sub-Neptunes, if at least some of them are water worlds, challenges this notion. Therefore, many sub-Neptunes have been thought to be large Earth-like planets with thick, hydrogen-rich atmospheres. We conducted a series of
experiments under the pressure-temperature conditions expected at the boundary between a hydrogen-rich atmosphere and the rocky interior of a sub-Neptune. We discovered reaction between hydrogen and magma that can release oxygen from silicate magma, allowing it to react with hydrogen and form water. This chemical reaction can transform a dry, hydrogen-rich planet into a water-rich planet even inside the snow line. I will also discuss how such reactions can impact the atmosphere, the interior, the size demographics, and the potential habitability of super-Earth exoplanets, many of which may have originated as sub-Neptunes.