The turbulent birth of planets
Dr. Wladimir Lyra
NASA Carl Sagan Fellow
Jet Propulsion Laboratory, California Institute of Technology
Tuesday, October 23, 2012

During the first million years of evolution, nascent planetary systems are embedded in dense disk-shaped clouds of gas. These circumstellar disks are home to a myriad of hydrodynamical and magnetohydrodynamical processes, which bring about turbulence and the emergence of viscous-like behaviour, enabling accretion of gas onto the protostar. Meanwhile, micron-size interstellar dust grains embedded in the disk are growing through coagulation onto pebbles and rocks. Turbulence has a positive effect on these small solids, concentrating them into transient pressure maxima for long enough to achieve gravitational collapse into km-sized bodies, forming the first planetesimals. Giant storm systems in the disk, similar to Jupiter's Great Red Spot may exist in the resistive quiescent zone of the disk. These are even more prone to collecting solid material, producing the first terrestrial planets and cores of giant planets. Once the planets are formed, N-body interactions, migration through the disk, and jitter from the turbulent gas define the system's final architecture. Concurrently, high energy photons from the central star slowly evaporate the gas, eventually leaving behind a disk of dust and debris. These debris disks tend to show a variety of non-trivial structures attributed to planetary perturbations and utilized to constrain the properties of the unseen exoplanets. In this talk I will review the state of the art and recent advances in the field of planet formation, and provide an alternative explanation for some of the structure seen in debris disks around young stars.