HET611 Stellar Astrophysics

Credit Points:
12.5

Duration & Workload:
One semester, equivalent to a 5 contact hour per week lecture course

Prerequisites:
HET603 Exploring Stars and the Milky Way, introductory tertiary-level mathematics and physics (or equivalent)

Aims:
This unit follows on from HET603 to introduce the student to the study of the physical processes underlying stellar properties and the principles behind models of stellar evolution.

Content:

This Unit, Stellar Astrophysics commences with an introductory section on classification systems for stars and their physical properties, and goes on to discuss the production of energy in stellar cores and the transport of this energy to the stellar surface. Stellar evolution is covered in depth, from star formation in dense molecular clouds, through the main sequence burning phase to the production of various stellar remnants, including white dwarfs, neutrons stars and black holes.

  • Classifying stars: magnitudes, colours, spectral types, luminosity classes; physical properties of stars: flux, luminosity, temperature, radius, mass; determining distances; stellar spectra; the HR diagram
  • Stellar energy: gravitational contraction versus fusion, nuclear binding energy, stellar nucleosynthesis, reaction rates, PP chain, CNO cycle, triple alpha process
  • Hydrostatic equilibrium and radiation pressure; equation of state; energy transport: opacity, absorption and emission mechanisms, convection; equations of stellar structure; stellar atmospheres
  • Protostars: cloud collapse, Jeans criterion and fragmentation, triggered star formation, the initial mass function, evolutionary tracks and the ZAMS, T Tauri stars, protostellar jets, accretions disks, proplyds
  • Main sequence stars: low mass and high mass stars, energy generation, PP chain versus CNO cycle; abundance profiles; the end of hydrogen core burning and lifetime on the MS
  • Evolution off the main sequence: low mass versus high mass stars; hydrogen shell burning, red giant branch, degenerate gas pressure, asymptotic giant branch, helium flash, the horizontal branch, dredge-ups, thermal pulsing, and nucleosynthesis; planetary nebula, white dwarfs, electron degeneracy pressure, the Chandrasekhar limit
  • Supernovae: type Ia and type II supernovae, light curves, explosive nucleosynthesis, supernovae remnants; galactic chemical evolution
  • Neutron stars: properties, neutron degeneracy, rotation, magnetic fields, pulsar lighthouse model, synchrotron radiation, spin-down and pulsar lifetimes, dispersion and distance measures, millisecond pulsars
  • Stellar mass black holes: formation mechanisms, escape velocity, Schwarzschild radius, event horizon spaghettification; Einstein's theory of general relativity, spacetime curvature; Hawking radiation, black hole evaporation
  • Pulsating stars: classed of pulsating stars and the instability strip, partial ionisation zones, opacity, thermodynamic heat engines; modelling pulsations, radial and non-radial modes, helioseismology
  • Binary stars: formation theories; evolution of close binaries: Roche limit and accretion disks, novae, cataclysmic variables, low mass and high mass X-ray binaries
  • Stellar clusters: types of clusters, open clusters and stellar evolution models, globular clusters and distances; colour-magnitude diagrams, metallicity, turn-off points
Teaching Method:
This unit will be presented in on-line delivery mode, with contact via newsgroup and e-mail.

Assessment Method:
Assessable newsgroup contributions, assignments and project.

Textbook:
For information about the textbook, follow this link