Uncovering the Hidden Ice Reservoir During Planet Formation

University Of Virginia Main Campus, Charlottesville VA

Investigators

Abstract

Water ice plays a key role in the formation of planetary disks and planets. Protoplanetary disk ices facilitate the growth of dust grains and planetesimals. Understanding the physical and chemical processes that drive ice chemistry is essential, because it is believed that icy planetesimals delivered bio-critical volatiles to the early Earth. Upcoming ground- and space-based observatories will probe ice in planetary disks, but interpreting ice observations will be challenging. This research team will model ice reservoirso, which will shed light on the detectability of ice features in disks under various conditions. These models will be invaluable for interpreting upcoming observations of disks' chemical abundances, physical state, evolutionary trajectory, and propensity for habitable planet formation. The team will conduct outreach to three different targeted age groups: middle schoolers, undergraduates, and the general public. They will collaborate on developing new programs with the Universty of Virginia's “Girls Exploring the Universe” summer program for middle school girls where the principal investigator serves as co-director. The team will also support the training of undergraduates. In partnership with local outreach organizations including Charlottesville's Astronomy on Tap, they will also engage the public on the topic of habitable planet formation and the important role played by ices. The team will create detailed time-dependent gas-grain chemical models to simulate the distribution and evolution of ices in planetary disks, followed by radiative transfer models to simulate observations of ice spectral signatures. The proposed work will provide the necessary theoretical underpinning to understand disk ice by: 1) Incorporating grain growth and material transport processes into the chemical evolution modeling; 2) Adding simulations of ice feature polarization to the radiative transfer modeling; 3) Conducting a sensitivity analysis of ices in various regions of the disk to better interpret which ice reservoirs are observable; 4) Exploring a parameter space of stellar, dust, and disk properties (including radial substructure) to predict their effects on disk ices; and 5) Studying the effect of a disk’s external environment (UV and cosmic ray fields) on observable ices. Thus, this investigation will explore the diversity of observable (and unobservable) disk icy reservoirs and their connection to the diversity of planet formation processes and outcomes. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.