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PHYS264 : Astrophysics I

Year:11/12
Department:Physics
Level:Part II (yr 2)
Learning Hours:75
Credit Points:7.5
Weight:0.25
Course Convenor:Dr DI Bradley
Status:Live

Assessment Rules

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  • 80% Exam
  • 20% Coursework

CMod description

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Overview of physical characteristics of stars; composition, mass, luminosity, surface temperature. Hertzsprung-Russell diagram, stellar population. Physics of Stellar Stability: Hydrostatic equilibrium, equations of state for an ideal non-relativistic gas of particles and an ideal gas of photons. The Virial Theorem, importance for stellar stability. Estimating the central pressure and temperature of a star. Criteria for stellar stability. Degrees of freedom, the adiabatic index γ. Generalised Virial Theorem, effects of mass pressure and radiation pressure. Relevance to main sequence stars and mass-luminosity relation. Energy generation in stars: Gravitational contraction, thermonuclear fusion. Binding energy per nucleon. Hydrogen burning, the proton-proton chain and the C-N-O cycle. Reaction rates, barrier penetration, temperature dependence. Energy transport in stellar interiors: Radiation and convection. Photon scattering mechanisms. Relative importance of mechanisms in different stars and different regions of stars. The Sun: Standard solar model. Helioseismology. Stellar models: Variation of physical properties with depth. Sensitivity of fusion reactions to central temperature. Importance of studying neutrinos. The solar neutrino problem. Other fusion reactions, helium burning, the triple alpha process, advanced burning, giant stars. Stellar evolution: star formation and evolution off the main sequence. Giants and variable stars. Overview of stellar relics: white dwarfs, neutron stars, black holes.

 

 

Curriculum Design: Outline Syllabus

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Overview of directly measurable physical characteristics of stars: Mass, luminosity, spectroscopy, stellar atmospheres, temperature, pressure, composition.

Hertzsprung-Russell diagram, stellar population and stellar evolution, importance of studying binaries and clusters.

Physics of Stellar Stability (main sequence): Gravitationally bound systems, ideal gases. Hydrostatic equilibrium, Virial Theorem.

Estimating central pressure and temperature. Conditions for stellar stability, effects of gas pressure and radiation pressure.

Energy generation in stars: Gravitational contraction, thermonuclear fusion, basic principles. Comparison of energy released and timescales for different stellar collapse processes and fusion processes.

Energy transport in stellar interiors: Radiative diffusion, photon scattering mechanisms, random walk statistics, convection, conduction.

The Sun: A typical main sequence star closely observed. The standard model, variation of physical properties with depth. Helioseismology.

Star birth: The interstellar medium, Jeans criterion for collapse of a nebula, protostars, formation and detection of planetary systems.

Evolution off the main sequence: Giant stars, pulsating variables. Limits to classical models for describing collapsing stellar cores.

 

Educational Aims: Subject Specific: Knowledge, Understanding and Skills

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To describe the physical properties of stars and review the astronomical techniques by which they are determined. To show how classical physics is successful in modelling many properties of main sequence stars and in explaining their formation and evolution.

To introduce some of the more complex stellar behaviour that cannot be understood on the basis of classical physics.

 

Learning Outcomes: Subject Specific: Knowledge, Understanding and Skills

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On completion of the module, students should:

- have a broad knowledge of the physical characteristics of the different types of star and nebulae, and the techniques by which they are determined.

- understand the basic physical principles of stellar stability, energy production and energy loss.

- be able to perform simple calculations relating to gravitational collapse, stability, lifetime and energy generation in well-behaved main sequence stars and in nebulae.

- be able to describe, as far as is possible using only classical physics, how stars are born and evolve.

 

Curriculum Design: Select Bibliography

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A C Phillips, Physics of Stars, Wiley

W J Kaufmann & Freedman, Universe, W H Freeman

B W Carroll & D A Ostlie, Modern Astrophysics, Addison Wesley

Lancaster University
Bailrigg
LancasterLA1 4YW United Kingdom
+44 (0) 1524 65201