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PX269 Galaxies

Lecturer: Peter Wheatley

Weighting: 7.5 CATS


To illustrate how important physical principles (taught elsewhere in the 1st and 2nd years) can be developed to yield a description of complex physical systems like galaxies. For example the module uses basic ideas from quantum physics, thermodynamics, mechanics and special relativity. The module also tries to illustrate how the same physical laws can be applied in very different situations.


After the module, you should

  • Understand the physical principles behind the observational methods used to study galaxies
  • Be able to show how observations of (for example) the energy output per unit volume and the widths and intensities of spectral lines may be interpreted to give infomation about galaxies and their constituent parts.
  • Be familiar with the standard models for galaxy formation, structure and evolution
  • Be aware of some of the outstanding and only partially understood problems in the study of galaxies including the nature of galaxy cores and the role of dark matter


Brief review of our assumptions about the state of the universe: Olber's Paradox, the Cosmological Principal, General Relativity.

Parameters and Measurement: Distance, Luminosity, Colour Index, the H-R Diagram, stellar clusters, spectroscopy.

Hierarchical structures: stellar clusters, galaxies, clusters, superclusters, walls, voids, filaments and sheets, gravitational lensing.

Spiral galaxy: morphology, constituents (stars, the ISM and ?), size and mass, stellar populations and their dynamics, the LSR, statistical astronomy, simple models.

Classification of Galaxies: The Hubble and other classification schemes, review of galactic types and their structure, elliptical galaxies.

Dark Matter and galactic evolution: Missing gravity (local and general), observation of mass, fundamental particles, baryonic and leptonic dark matter, MACHOS, WIMPS, exotic particles - Axions, topological defects and singularities, stellar mass black holes, cold and hot dark matter.

Exotic galaxies and AGN's: Seyfert galaxies, Starburst galaxies, Quasars - Remote objects, red shift, age of universe

Commitment: about 18 Lectures

There are a number of handouts which revise or pull together material where this has been taken from other modules. Whilst the Stars option is not a prerequisite for this module, it is useful background for those with no prior knowledge of astrophysics.

Assessment: 1 hour examination.

Recommended Texts: RJ Tayler, Galaxies: structure and evolution, CUP; B Jones, RJA Lambourne and DA Rothery, Images of the Cosmos, The Open University; B Jones, Galaxies, The Open University

Leads from: PX268 Stars

Leads to: PX389 Cosmology and PX387 Astrophysics