ASTRONOMY COLLOQUIUM (Biard Lecture)

When planets assemble in disks around young stars, they accrete material that originates in molecular clouds. Disks are not just passive reservoirs of this material, however, but shapes it in chemically interesting ways with profound impacts on planetary compositions. In this talk I will introduce some of the puzzles presented by protoplanetary disk and solar system chemistry observations, how they impact our current understanding of inheritance vs disk production of volatiles, and how theoretical and laboratory work can help elucidate what the chemical environments of planet formation are like. In particular we will examine why some planet-forming disks appear so water-rich and others water-poor, the origin of hyper-volatile-rich or even hyper-volatile-dominated comets, how reliable isotopic ratios really are for constraining the origins of water and other volatile species, and hence what we currently know about the origins of water and organics during planet formation. In each case we will find that chemical processes on the surfaces of microscopic dust grains fundamentally impact the volatile inventories available to forming planets and planetesimals.