Origins Seminar and TAP Planet Formation Initiative Lecturer, Fred Adams

Origins Seminar and TAP Planet Formation Initiative Lecturer, Fred Adams, University of Michigan

Title:  Revisiting the Core Accretion Paradigm for Giant Planet Formation: Analytic Framework for the Late Infall Stage and the Distribution of Planetary Masses

Abstract:  This talk presents an analytic description for the late stages of giant planet formation, when planets gather the majority of their mass. The resulting solutions show how the protoplanet properties (envelope density distribution, velocity field, column density, disk surface density, system luminosity, and emergent spectral energy distributions) vary with the input parameters of the problem (instantaneous mass, orbital location, accretion rate, and planetary magnetic field strength). We then construct a framework for calculating the distribution of planet masses resulting from this paradigm. In this scenario, the disk lifetime determines the end of mass accretion onto the planet. The mass accretion rate depends on the size of the Hill sphere, the fraction of the disk accretion flow that enters the sphere of influence, and the efficiency with which the planet captures the incoming material. The resulting model produces a planetary mass function with a nearly power-law form, roughly consistent with current observational estimates.

BIO:  Born in Redwood City, California, Fred Adams graduated from Iowa State University in 1983 with a BS in Physics and Mathematics. He went on to receive his PhD in Physics from the University of California, Berkeley (in 1988), where his dissertation received the Robert J. Trumpler Award from the Astronomical Society of the Pacific. After serving as a postdoctoral research fellow at the Harvard-Smithsonian Center for Astrophysics, Adams joined the faculty in the Physics Department at the University of Michigan in 1991. Adams was promoted to Associate Professor in 1996, and to Full Professor in 2001. He is the recipient of the Helen B. Warner Prize from the American Astronomical Society and the National Science Foundation Young Investigator Award. At the University of Michigan, he has been awarded the Excellence in Education Award, the Excellence in Research Award, the Faculty Recognition Award, and was elected to the Michigan Society of Fellows. Adams was subsequently elected to be a fellow of the American Physical Society, fellow of the American Astronomical Society, and Chair of the AAS Division on Dynamical Astronomy. He was named as the Ta-You Wu Collegiate Professor of Physics at the University of Michigan, and is currently the director of the Leinweber Center for Theoretical Physics.

 Professor Adams works in the general area of theoretical astrophysics with a focus on the study of star formation, exoplanets, and cosmology.  He is internationally recognized for his work on the radiative signature of the star formation process, the dynamics of circumstellar disks, the development of a theory for the initial mass function, and studies of extra-solar planetary systems.  In cosmology, he has studied the inflationary universe, magnetic monopoles, cosmic rays, and cosmic background radiation fields.  His work in cosmology also includes explorations of the long term fate and evolution of the universe, as well as a re-examination of its degree of fine-tuning. 

Author of “The Five Ages of the Universe”