Dust-Gas Dynamics In and Out of Rings

The general picture that planets form in a protoplanetary disk, the spinning disk of gas and dust that surround young stars, is well established. How exactly planet formation proceeds from disks to planetary systems remains less clear due to uncertain properties of gas dynamics and the coupling of solid particles to the gas. Through computer simulations of the process of planet formation in rings, this research team will make predictions for the occurrence of planets that are currently too small to be detected but will soon be measured. The project will leverage social media to communicate scientific topics to a large, public audience. The new Department of Astronomy & Astrophysics at UC San Diego administers an Instagram account, which this project’s personnel manages and regularly updates with reels (short videos) showcasing astrophysical concepts and cutting-edge research by Department members. Graduate students in the Department will sharpen their scientific communication skills useful in academia and beyond in a formal professional development course to be developed as part of this project, including a module to produce the Instagram reels. The uncertain parameters of macro- and micro-physics in modern theories of planet formation severely limits their predictive power. This project breaks the measurement degeneracy between the Stokes number St and gaseous effective viscosity alpha, parameters that characterize the initial conditions of planet formation, by combining a large sample of ringed disks with the dust equation of motion. Direct simulations of the formation and mass growth of clumps inside dust rings will be pursued with the GIZMO hydrodynamic code, including self-gravity and sampling the observationally-inferred range of St and alpha. Prediction for the planet mass function at orbital distances of several to tens of astronomical units will be derived from the results of the GIZMO simulations convolved over the Galactic distribution of host star, disk, and environmental properties. Altogether, the proposed research has the potential to significantly advance our understanding of the critical microphysical properties of the protoplanetary disks and to make a direct link between these initial conditions and the properties of the observable exoplanets, producing specific and timely theoretical predictions of a distance-dependent planetary mass function that can be tested with upcoming observations. 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.