PHY3142 Stars From Birth to Death

2011-2012

Code: PHY3142
Level: 3
Title: Stars From Birth to Death
Instructors: Dr T.J. Harries
CATS Credit Value: 10
ECTS Credit Value: 5
Pre-requisites: N/A
Co-requisites: N/A
Duration: T1:01-11
Availability: unrestricted
Background Assumed: Statistical Physics (PHY2201) and Quantum Physics I (PHY2002)

Total Student Study Time

100 hours, to include: 20×1-hour lectures; 2×1-hour problems classes; 8 hours problems sets; 15 hours guided reading; 55 hours private study.

Aims

The study of stellar systems encompasses a wide range of physics, including gravitation, quantum mechanics, and thermodynamics. This module takes these fundamental physical concepts, learned in the core courses, and uses them to derive the properties of stars. The basic internal structure of stars is described in the first lectures, while later lectures deal with the ageing and death of both high- and low-mass objects. The final lectures describe how stars and planetary systems form.

The specific aim of the module is to provide the students with a detailed understanding of the physics that govern stellar structure and evolution. In addition the students will be familiar with topics at the forefront of current astrophysical research, such as star and planet formation.

Intended Learning Outcomes

Students will be able to:

Module Specific Skills:
1. describe the fundamental properties of stars;
2. use the equation of hydrostatic equilibrium to estimate the core properties of stars;
3. calculate the dynamical, thermal, and nuclear timescales of stars;
4. describe the main nuclear reactions that power high and low mass stars;
5. describe how radiation is transported from the stellar core to the surface;
6. discuss post-main sequence evolution for high and low mass stars;
7. describe the physics of compact stars and derive the mass-radius relationship for white dwarfs;
8. discuss the terminal stages of stellar evolution;
9. calculate the Jeans mass and describe the process of star and planet formation;
Discipline Specific Skills:
1. solve mathematical problems;
2. apply quantum and classical mechanics, and thermal physics to stellar systems;
Personal Transferable Skills:
1. develop self-study skills;
2. solve problems.

Learning / Teaching Methods

Lectures, e-learning resources, guided reading, and problem sets.

Assessment and Assignments

Contribution	Assessment/Assignment	Size (duration/length)	When
100%	Final examination	120 minutes	Week T2:00
Formative	Problem sheets	2×4-hour sets	T1:05, T1:10

Syllabus Plan and Content

General Properties of stars
1. Definition of a star
2. Observable quantities
3. Distance determination
4. Mass determination
5. Luminosity and effective temperature
6. Black body radiation
7. Magnitude, colors and spectral types
Basic approach: Dimensional analysis
1. Hydrostatic Equilibrium
2. Virial theorem
3. Characteristic timescales
  1. Dynamical or 'free fall' timescale
  2. Thermal timescale or Kelvin-Helmholz timescale
  3. Nuclear timescale
  4. Stellar lifetime on the Main Sequence
4. Mass-luminosity relationship
Stellar structure equations
1. Coordinates and mass distribution
  1. Eulerian description
  2. Lagrangian description
2. Hydrostatic equilibrium
3. Equation of motion for spherical symmetry
4. Energy conservation
5. Energy transport mechanisms
  1. Radiative transport of energy
  2. Convective transport of energy
  3. Conductive transport of energy
Thermodynamical properties of matter
1. Ideal gas with radiation
  1. Fully ionized matter
  2. Partial ionisation
2. Degenerate electron gas
  1. Consequence of Pauli's principle
  2. Complete degenerate electron gas
  3. Partial degeneracy
3. Effect of degeneracy on stellar evolution
4. Non ideal effects
Nuclear reactions and main burning phases in stars
1. Basics of thermonuclear reactions
  1. Mass excess
  2. Binding energy
  3. Coulomb barrier
  4. Tunnel effect or quantum tunneling
  5. Cross sections and reaction rates
2. Major nuclear burning phases in stars
  1. Hydrogen burning
  2. Helium burning
  3. Advanced stages
3. Ultimate stages
Energy transport properties
1. Opacity of stellar matter
  1. Bound-bound absorption
  2. Bound-free absorption
  3. Free-free absorption
  4. Electron scattering (Thomson scattering)
Principles of stellar evolution
1. Polytropes
  1. Definition
  2. Example of polytropic relations in real stars
  3. Equations for a polytrope
  4. Mass-radius relationship
  5. Chandrasekhar's limiting mass
2. Numerical models
  1. Contraction toward the Main Sequence
  2. Evolution on the Main Sequence
  3. Final stages: the death of stars
    White dwarfs; Supernovae, Remnants of supernovae: Neutron stars, black holes
Instabilities and stellar pulsations
1. Stability considerations
2. Stellar pulsations
  1. Special case of Cepheids
  2. Basics of stellar pulsation theory
Star formation
1. Properties of interstellar medium and clouds
2. The Jeans length and mass
  1. Gravitational instability criterion
3. Fragmentation process

Core Text

Not applicable

Supplementary Text(s)

Bowers R.L. and Deeming T. (1984), Astrophysics 1 - Stars, Jones and Bartlett, ISBN 0-86720-018-9 (UL: 523.01 BOW/X)
Phillips A.C. (1999), The Physics of Stars (2^nd edition), Wiley, ISBN 0-471-98797-2 (UL: 523.8 PHI)

Formative Mechanisms

This module is supported by problems classes. Students are able to monitor their own progress by attempting problems sheets provided in the lectures. Students with specific problems should first approach their tutor, and if the problem is not resolved, the lecturer.

Evaluation Mechanisms

The module will be evaluated using information gathered via the student representation mechanisms, the staff peer appraisal scheme, and measures of student attainment based on summative assessment.