2002 Annual Science Report
University of Washington Reporting | JUL 2001 – JUN 2002
Dynamics of Comets, Asteroids, and Planets
Lucio Mayer and Tom Quinn have performed Smooth Particle Hydrodynamics (SPH) simulations of massive protoplanetary gaseous disks using unprecedented resolution. In particular, the SPH technique allows them to study a large dynamic range in density, so that the collapse of protoplanets can be followed in a full disk simulation. After performing a number of convergence tests verifying the accuracy of the simulation technique, they have been able to show that such disks become gravitationally unstable and form condensations along spiral arms that contract to protoplanetary densities in a few hundred years. These protoplanets have masses and orbital eccentricities remarkably similar to those of observed extrasolar planets. See the citations for where this work has been presented.
Thomas Quinn and Rory Barnes continue to integrate orbits of extra-solar planetary systems to determine their stability. For nearly all of the multi-planet systems so far discovered, the
Simulations indicate that the planetary systems are located on the “edge” of stability. That is, if the planet orbits were any more eccentric or inclined than what they are observed to be, theywould be unstable on million year timescales. See the citations for where this work has been presented.
In collaboration with J. Lissauer of NASA Ames, Barnes and Quinn are following the very early stages of planetesimal accretion. This is being performed with a high performance parallel code that calculates the gravitational attraction and collisions between planetesimals. The first question they are addressing is the mass distribution of planetesimals.
Kyle Sunqvist performed integrations of the delivery rates of comets into the terrestrial region over the history of the Solar System assuming larger and smaller masses for the giant planets. A basic result is that as masses of the Giant planets are changed, the region from which comets are delivered into the terrestrial region changes little, but the timescale for delivery changes drastically.
PROJECT MEMBERS:Thomas Quinn
RELATED OBJECTIVES:Objective 1.0
Determine whether the atmosphere of the early Earth, hydrothermal systems or exogenous matter were significant sources of organic matter.
Describe the sequences of causes and effects associated with the development of Earth's early biosphere and the global environment.
Determine the presence of life's chemical precursors and potential habitats for life in the outer solar system.
Determine (theoretically and empirically) the ultimate outcome of the planet-forming process around other stars, especially the habitable ones.