**Galactic
Astronomy ****and Dynamics** (Lent 2012)

## Brief Synopsis

Astrophysics provides many examples of complex dynamical systems. This
course covers the mathematical tools to describe Galaxies as well as
reviewing their observational properties. The behaviour of these systems
is controlled by Newton's laws of motion and Newton's law of gravity.
Galaxies are dynamically very young, a typical star like the Sun having
orbited only thirty or so times around the galaxy. The motions of stars in
Galaxies are described using classical statistical mechanics, since the
number of stars is so great. The study of large assemblies of stars
interacting via long-range forces provides many unusual examples of
cooperative phenomena, such as bars and spiral structure. The interplay
between astrophysical dynamics and modern cosmology is also important --
much of the evidence for dark matter is dynamical in origin.

## Syllabus

Observational overview. Stellar populations in galaxies, galaxy
morphology and classification. Dust and gas in galaxies. Scaling Laws.
Theory of the gravitational potential. Poisson's equation. The gravity
field of spherical. elliptical and disk galaxies. Regular and chaotic
orbits, the epicyclic approximation, surfaces of section, action-angle
coordinates, adiabatic invariance. Collisionless stellar dynamics,
the Boltzmann equation, the Jeans theorem, the Jeans equations,
equilibrium models of spherical, elliptical and disk galaxies.
Collisions, collisional dynamics, the Fokker-Planck equation. Globular
cluster evolution, evaporation and ejection, the gravothermal
catastrophe, hard and soft binaries. Galactic stability, The Jeans
length, theories of spiral structure, the role of resonances. The
Milky Way Galaxy, the thin disk, thick disk and halo, substructure and
tidal streams

## Problem Sheets

There will be four examples class associated with the course. Three
are given this term in the Hoyle
Committee Room, Institute of Astronomy.

Problem
sheet 1: Warming-up and Potential Theory.
## On-Line Resources

## Books

Binney J., Merrifield M., Galactic Astronomy, Princeton Univesrity Press
Binney J., Tremaine S., Galactic Dynamics, Princeton University Press
Bertin G., Dynamics of Galaxies, CUP
Heggie D., Hut P., The Million Body Problem, CUP
Sparke L., Gallagher J., Galaxies in the Universe: An Introduction,
CUP
Spitzer L., The Dynamical Evolution of the Globular Clusters,
Princeton University Press