2:00–3:00 pm Henry Hinds Laboratory, Room 101
Title: Formation Of Earth By Pebble Accretion And Impacts
Abstract: Understanding how our planet formed is a central question at the intersection of astrophysics, planetary science, cosmochemistry, and geochemistry. Observations of protoplanetary disks around young stars over the past two decades have revealed that these planet-forming disks contain large populations of millimeter- to centimeter-sized pebbles. This discovery led to the development of the pebble accretion theory, which suggests that planets primarily grow by accreting small pebbles, in contrast to the classical view that planets grow through collisions with asteroid-sized planetesimals. While pebble accretion appears essential for explaining the formation of gas giant planets far from their host stars, its role in the formation of terrestrial planets remains a subject of intense debate. I will present evidence from the isotopic and elemental composition of Earth indicating that pebble accretion played a significant role in Earth’s formation. However, the same data reveal that planetesimal accretion and the giant moon-forming impact also made substantial contributions. Therefore, I propose a hybrid accretion model for terrestrial planets and discuss its implications for volatile delivery and for the composition of primordial planet atmospheres.
Host: Fred Ciesla
This event is free and open to the public. If you need assistance to attend, please contact ccady@uchicago.edu