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PYU33A03 Stellar and Galactic Structure

Michaelmas Term – 30 lectures/tutorials – 5 credits (J Groh)

Part I: Stellar Astrophysics
Part II: Galaxies: From the Milky Way to Quasars

Learning Outcomes
On successful completion of this module, students should be able to:

  • Describe the major stages in the evolution of a star from birth to death
  • Explain the Hertzsprung-Russell diagram for stellar populations of different ages
  • Manipulate the basic equations for stellar structure and evolution in order to derive elementary results for global stellar properties and timescales
  • Derive the basic equations governing the dynamics of the Sun and nearby stars with respect to the Galaxy
  • Explain the distribution of stars, gas and dust within galaxies, and describe the properties of the various types of galaxies found in the Universe
  • Discuss the evidence for massive black holes at the centres of active galaxies and for Dark Matter in the Universe on a variety of scales


Part I: Stellar Astrophysics
The structure of a star is regulated by the balance between gravity and pressure, and is almost entirely governed by its mass and chemical composition.
We discuss the physics of stellar material, including the equation of state and radiative opacity, as well as major energy transport processes. A star's evolution is dictated by nuclear reactions which produce heat and transform chemical structure. We explore how stars evolve from clouds of interstellar gas to become main-sequence stars like the Sun, and then expand to become red giants and helium-burning stars. We examine the final stages of stellar evolution, including white dwarfs, supernovae and neutron stars. The use of binary stars and pulsations for testing the stellar structure theory will be demonstrated. 

Part II: Galaxies: From the Milky Way to Quasars
Gravitational forces determine the movements of the stars within a galaxy. Several aspects of this basic problem will be considered, such as space distribution of stars, stellar velocity distribution, high-velocity stars, rotation curve of stellar systems, integrals of motion, individual stellar orbits. The stars moving around in elliptical galaxies exhibit triaxial velocity ellipsoids, while the ordered motion in disk systems gives rise to spiral density patterns. The stellar movements indicate that large amounts of unseen mass may be associated with galaxies and with clusters of galaxies. Many details of stellar dynamics become evident in the close surroundings of our own Galaxy where a large body of observational data assists our understanding.






Continuous Assessment in Galaxies: From the Milky Way to Quasars