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Earth and Planetary Sciences Seminar: Dr. Dan Shim - Building a Wet Planet from Dry Materials

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It has been believed that water-rich planets are formed outside the snow line.  However, discovery of many close-in orbiting sub-Neptunes, if at least some of them are waterworlds, challenges the notion.  Therefore, many sub-Neptunes have been believed to be instead large Earth-like planets with thick hydrogen rich atmosphere. We have conducted a series of experiments under the pressure-temperature conditions expected at the boundary between hydrogen-rich atmosphere and rocky interior of a sub-Neptune.  We found a reaction between hydrogen and magma which can unlock oxygen from silicate magma and enable oxygen to react with hydrogen to form water. The chemical reaction can convert a dry hydrogen-rich planet to a water-rich planet even inside the snow line.  I will also discuss how such reaction can impact the atmosphere and the potential habitability of super-Earth exoplanets, many of which may be converted from sub-Neptunes.

Dan Shim is a Navrotsky professor of materials research at the School of Earth and Space Exploration at Arizona State University. His research interests include the physical and chemical properties of materials at high pressures and temperatures and their implications for the structure and the evolution of Earth and planetary interiors. He earned his Ph.D. in geosciences from Princeton University. He was a Miller Research Postdoctoral Fellow at the University of California Berkeley. He worked at MIT as an assistant and associate professor until 2012, when he joined Arizona State University. 

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