ASTRONOMY COLLOQUIUM

Super-Earths and sub-Neptunes are the most abundant exoplanets discovered to date. Recent models of atmospheric evolution and erosion by core-powered mass loss and photoevaporation suggest that these two populations of exoplanets might have been born as one. In these models, close-in, lower-mass planets lose their hydrogen–helium envelopes and become rocky super-Earths, whereas more massive, longer-period planets retain primordial H/He envelopes and remain sub-Neptunes. In my talk, I will explore the question as to how primary, hydrogen-rich atmospheres influence the physical evolution and chemical composition of super-Earths and sub-Neptune exoplanets and show that Earth's water, core density deficit, and overall oxidation state can all be sourced to equilibrium between hydrogen-rich primary atmospheres and underlying magma oceans in its progenitor planetary embryos. Reaction with hydrogen atmospheres thus provides a simple explanation for fundamental features of Earth's geochemistry that is consistent with rocky planet formation across the galaxy. 

To view this talk on YouTube, please visit: https://www.youtube.com/playlist?list=PLb1880Rn0qkKFkWyROUq1kRlgCsuBTrnd