PHY3142 Stars From Birth to Death

2007-2008

Code: PHY3142
Title: Stars From Birth to Death
Instructors: Dr T.J. Harries
CATS credits: 10
ECTS credits: 5
Availability: unrestricted
Level: 3
Pre-requisites: N/A
Co-requisites: N/A
Background Assumed: Statistical Physics (PHY2201) and Quantum Physics I (PHY2002)
Duration: Semester II
Directed Study Time: 22 lectures
Private Study Time: 78 hours
Assessment Tasks Time: -
Observation report: 2002/03 AU

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 should be able to:

Module Specific Skills

• describe the fundamental properties of stars;
• use the equation of hydrostatic equilibrium to estimate the core properties of stars;
• calculate the dynamical, thermal, and nuclear timescales of stars;
• describe the main nuclear reactions that power high and low mass stars;
• describe how radiation is transported from the stellar core to the surface;
• discuss post-main sequence evolution for high and low mass stars;
• describe the physics of compact stars and derive the mass-radius relationship for white dwarfs;
• discuss the terminal stages of stellar evolution;
• calculate the Jeans mass and describe the process of star and planet formation;

Discipline Specific Skills

• solve mathematical problems;
• apply quantum and classical mechanics, and thermal physics to stellar systems;

Personal and Key Skills

• develop self-study skills;
• solve problems.

Learning and Teaching Methods

Lectures, on-line teaching resources, guided reading, and problem sets.

Assignments

Problem sheets to be completed as homework.

Assessment

One 90-minute examination (100%).

Syllabus Plan and Content

1. Stellar parameters (1 lecture)
   1. Observables (luminosities, temperatures, masses, radii, composition)
   2. HR diagram, the role of clusters
   3. Stellar populations
2. Stucture of Stars (3 lectures)
   1. The equation of state
   2. The equation of mass continuity
   3. Hydrostatic equilibrium
   4. Radiation pressure
   5. The Eddington Limit
   6. The Virial Theorem
   7. Stellar timescales (dynamical and thermal, nuclear)
   8. Thermal equilibrium
3. Energy Generation (2 lectures)
   1. The mass defect
   2. The proton-proton chain
   3. The CNO cycle
   4. Further nuclear reactions; the r and s process; the origin of the heavy elements
4. Energy transport (3 lectures)
   1. Radiation; conduction; convection
   2. Radiative transfer; intensity and flux
   3. Absorption coefficient and optical depth
   4. The emission coefficient and the source function
   5. Local Thermodynamic Equilibrium
   6. Convection (cores of massive stars, envelopes of low mass stars); mixing length theory
5. Stellar Evolution (3 lectures)
   1. Main sequence evolution
   2. Stellar pulsation
   3. Post MS evolution for solar mass stars
   4. Post MS evolution for high mass stars
6. Stellar Death (4 lectures)
   1. White dwarfs
      1. Properties of matter at high densities; Fermi pressure
      2. Mass-radius relation
      3. Relativistic case and Chandrasekhar mass limit
   2. Neutron stars
      1. Inverse beta-decay
      2. Equations of state
      3. Pulsars
   3. Supernovae
      1. Type Ia (Binary evolution, white dwarf mergers)
      2. Type II (Nuclear burning to Fe, role of neutrinos, SN1987A)
   4. Stellar-mass black holes
      1. Properties of black holes
      2. X-ray binaries and black hole masses
      3. Gamma-ray bursts; Collapsars
7. Star formation (4 lectures)
   1. Properties of the interstellar medium
   2. The Jeans mass
   3. Free-fall collapse of an homogeneous sphere - non-rotating case
   4. Collapse with rotation; accretion discs; jets
   5. Fragmentation; multiple stars
   6. The protostar; Hyashi and Henyey evolutionary tracks
   7. The Initial Mass Function; deuterium burning brown dwarfs; free floating planets
8. Planet formation (2 lectures)
   1. The solar system (terrestrial planets; gas giants; asteroids)
   2. Exoplanet observations
      1. Doppler reflex measurements
      2. Transit observations
      3. Microlensing
      4. Reflected light
   3. Hydrodynamics (planet formation; orbit migration)

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.