Planet Formation under the Microscope: The Role of Ice Physics and Chemistry in the Compositions of Nascent Planets

Karin Öberg (Harvard)

During the past decade, the number of known exoplanets has increased explosively, revealing an extreme range in planet compositions. A handful of the detected planets are theorized to be "habitable," i.e., of the right temperature and bulk composition. This raises two important questions: what processes set the bulk compositions of planets and how often are "habitable" planets actually chemically habitable, i.e., rich in water and organic material. Both questions are intimately linked to the composition of the gas and solids that planets assemble from, and especially to the processes that regulate ice build-up, chemical evolution, and sublimation. To address these questions, we use spatially- and spectrally-resolved observations to map out the distributions of bulk and trace volatiles in protoplanetary disks, the formation sites of planets. In parallel, we carry out laboratory ice experiments to explore and quantify the processes that regulate the observed volatile abundance patterns. Recent highlights include observations of spectacular ring structures that trace condensation fronts in disks, new constraints on isotopic fractionation in volatiles during planet formation, and the detection of the first complex organic molecule in a disk.