Investigating the evolution of material properties during planet formation
2 - 30 November, 2023
Biography
Sarah T. Stewart is a Professor in the Department of Earth and Planetary Sciences at the University of California, Davis. She joined the faculty at Davis in 2014 after 11 years as a Professor at Harvard University.
Sarah is a planetary scientist who specializes in the study of collisions in the solar system. Her research encompasses the formation and destruction of planets, planetary geology, and materials science. She is best known for proposing a new model for the origin of the Moon, where the Moon grows within a new type of planetary object known as a synestia. Sarah’s experimental program on planetary materials focuses on measurements of thermodynamic properties and calculating the mass of melt and vapor produced during planetary impact events. Sarah directs the Shock Compression Laboratory, which uses light gas guns to study shock waves in planetary materials, and also conducts shock experiments on laser and pulsed power platforms.
Sarah received her AB in Astrophysics and Physics from Harvard in 1995 and her PhD in Planetary Science from the California Institute of Technology in 2002. She has won awards and honors for her scholarship, including a MacArthur Fellowship, the Urey Prize from the American Astronomical Society’s Division for Planetary Sciences and a Presidential Early Career Award for Scientists and Engineers. Sarah was President of the Planetary Sciences Section of the American Geophysical Union from 2016-2018. Sarah is dedicated to public outreach in planetary sciences and is featured as one of Popular Science’s Brilliant 10 of 2010 and Astronomy Magazine’s Rising Stars of 2013. Sarah is a 2018 MacArthur Fellow and 2019 AAAS Fellow
Research Summary
During the Visiting Professorship, Prof. Stewart will pursue fundamental science research in planet formation focusing on linking understanding of the physical properties of planets with (1) exoplanet observations and (2) studies of meteorites in our Solar System. Prof. Stewart will collaborate with Drs. Leinhardt, Lock and Carter, physicists and dynamicists with a strong focus on exoplanetary studies and planet formation in general, and with Dr. Elliott, an isotope geochemist and expert in meteorites. Dr. Stewart’s work on planetary materials at high pressures and temperatures is a key aspect of understanding the diversity of exoplanets. As a leader in the high-pressure physics community, Stewart is working to develop stronger connections between the high-pressure community and the international exoplanet communities.The major goals for the BBMDVP are (1) to develop new ideas for proposals for high-energy experiments to understand planetary interiors; (2) develop new techniques to model planetary collisions and interiors, particularly linking material properties to dynamical simulations; (3) collaborate on a publication on the mysterious origin of meteorites that have a distinct isotopic similarity to Earth.
Prof. Stewart is hosted by Dr Zoe Leindhart.
Planned lectures and seminars include:
Physics Lecture - Can Collisions Create Earth’s Isotopic Cousins?
November 9, 2-3pm, Biomedical Building C44
Our planets are mixtures of different materials, which can be identified by distinct isotopic compositions. Earth has isotopic cousins – enstatite chondrites and the Moon-forming impactor – that formed long before Earth’s accretion was complete. Here, I explore the role of collisions and planet migration in creating small to large bodies with similar isotopic compositions. During planet formation, collision velocities surpassed the thresholds for the onset of vaporization of all the major components. New laboratory and modeling studies of vaporizing collisions have discovered new phenomena during planet formation that may explain major questions about the origin of Earth and its isotopic cousins.
Public Lecture - The Origin of the Earth and Moon
November 15, 6-7pm, G42 Powell LT, School of Physics
Abstract The origin of the Earth and Moon is one of science’s greatest mystery stories. The Apollo missions shattered previous ideas, but lunar samples contain a major clue to our planet’s creation: the Moon is Earth’s isotopic twin. The isotopes of elements are like a planetary fingerprint: no two bodies are the same – except the Earth and Moon. After Apollo, a giant impact became the leading explanation for the Moon, but it failed to explain this key observation. Stewart will explain how the discovery of a new type of astronomical object, called a synestia, can save the giant impact hypothesis.
Earth Sciences Lecture - Exploring the SiO2 system with shock waves
November 16, 12noon - 1pm, Room G7, Wills Memorial Building
Shock compression can explore regions of the phase diagram that are inaccessible by static techniques. Shock temperature measurements of fused silica and alpha-quartz have been interpreted to overshoot the equilibrium melt curve due to the kinetics of melting. Here, I will summarize the available shock data, kinetic processes, and a new reconciliation between static and shock determinations of the melt curve.
