Big Question: Searching for Water in Distant Worlds

Principal Investigator: Leslie Rogers, Astronomy & Astrophysics

Funding Type: Seed

Big Idea: The abundance of Neptune-size (2 to 6 Earth-Radius) planets discovered by Kepler is a puzzle for planet formation theories. Did these planets form in situ at orbital separations (<0.4 AU) near where they are currently observed, or did they initially form beyond the snow line before later migrating inward toward their host star? The bulk water content of a planet is a powerful tracer of the planet's formation location. With current transit, radial velocity, and atmospheric spectra observations, however, it is challenging to constrain the fraction of an exoplanet’s total mass contained in astrophysical ices. We propose to investigate whether immiscibility between water and hydrogen may provide observable signatures of the presence of water in the deep interior of Neptune and sub-Neptune-size exoplanets. The seed project will instantiate a pilot study of ab initio calculations of the properties of H2-H2O mixtures at pressures exceeding 1GPa.