Astronomy 250:  Special Topics in Astrophysics

Fall 2002

Planetary Dynamics





Gravitational dynamics of planetary bodies. The goal will be to understand the orbital motions of planets and satellites, both in extrasolar systems and in the solar system. To develop intuition, we will begin with classical analytic descriptions of the N-body problem. We will then introduce modern, powerful numerical integration techniques. Having developed an understanding of point-mass interactions, we will impart shapes to planetary bodies to study tides and spin-orbit coupling. We will achieve a quantitative understanding of celebrated case studies in planetary dynamics, including resonant dynamics in the extrasolar planetary systems Upsilon Andromedae and GJ 876; the chaotic obliquity of Mars; the origin of Plutinos in the Kuiper Belt; and the sculpting of planetary rings by shepherd moons.


Instructor:   Eugene Chiang (Departments of Astronomy and of Earth and Planetary Science )

Time & Place:   Tuesdays and Thursdays 2:00 - 3:30 in 501 Campbell Hall

Format:   Weekly lectures and problem sets. Each problem set will contain 3 problems. For registered students, a reasonable attempt at 1 problem of your choice out of every 3 will be required. As the course progresses, we may interleave the lectures with round-table discussions of famous journal articles.

Office Hours:   Anytime I am around and am not talking with anybody else. For guaranteed meeting times, e-mail me (echiang@astron.berkeley.edu).

Text:   Solar System Dynamics by Murray & Dermott. Supplemental journal articles.

Course Outline:   Click on the hyperlink to find readings and problems.

I. Tour of the Mechanical Universe
II. The 2-Body Problem PDF version
       A. Osculating elements of the Keplerian ellipse
       B. Useful relations
       C. Guiding center description
       D. Kicking the 2-body problem: Gauss's perturbation equations
       E. Hamiltonian description and changing canonical variables
      Solutions to PS 1 PDF version
III. The Restricted 3-Body Problem PDF version
       A. Hill's equations
       B. The Jacobi constant
       C. Lagrange points
       D. Horseshoes, tadpoles, and Trojan extrasolar planets
      Solutions to PS 2 PDF version
IV. The (Very) Disturbing Function PDF version
       A. Strengths and arguments
       B. Secular, resonant, and short-period terms
       C. Lagrange's potential equations
      Solutions to PS 3 PDF version
V. Secular Theory PDF version
       A. Wires
       B. Laplace-Lagrange theory for eccentricities and inclinations
             1. Extrasolar planets: Upsilon Andromedae
             2. Kuiper Belt collisional families
       C. Secular resonances
             1. Kozai and Extrasolar Planets: 16 Cyg AB
             2. Planetary Rings: Uranian Epsilon Ring
      Solutions to PS 4 PDF version
VI. Resonance Theory PDF version
       A. Good and bad phasing
       B. Metronome model
       C. Resonant widths
       D. Resonance encounters
             1. Capture: Extrasolar system GJ 876 and planetary satellites
             2. Passage: Divergent crossings and eccentricity excitation of extrasolar planets
       E. Reading for Tuesday October 1: Resonant Capture by Inward-Migrating Planets,
             by Yu & Tremaine (2001)
       F. Reading for Thursday October 17: Structure in the Dusty Debris around Vega,
             by Wilner et al. (2002)
       G. OPTIONAL SUPPLEMENTAL Reading for Thursday October 17:
             The Geometry of Resonant Signatures in Debris Disks with Planets
             by Kuchner & Holman (2002)
      Solutions to PS 5 PDF version
VII.  Chaos, Integration Techniques, and Long-Term Evolution
       A. Lyapunov exponent
       B. Resonance overlap criterion
       C. Chaotic orbit of Pluto
       D. Wisdom's Resonance Map and the Kirkwood Gap of Asteroids
       E. Wisdom-Holman N-Body Symplectic Map
       F. Reading for Thursday November 7: Dynamical Stability in the Outer Solar System
             by Holman & Wisdom (1993)
       G. Reading for Thursday November 7: Dynamical Structure of the Kuiper Belt
             by Duncan, Levison, & Budd (1995)
             **Color figures of DLB here**
       H. Reading for Thursday November 14: Origin of Chaos in the Outer Solar System
             by Murray & Holman (1999)
VIII. Tides and Spin-Orbit Coupling PDF version
       A. Damped spring model and tidal Qs
       B. Tidal migration
       C. Eccentricity damping of hot Jupiters
       D. Evolution to synchronicity
       E. Chaotic obliquity of Mars
      Solutions to PS 6 PDF version