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# The Physics of Stars - PHY00058H

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• Department: Physics
• Module co-ordinator: Dr. Charles Barton
• Credit value: 10 credits
• Credit level: H
• Academic year of delivery: 2021-22
• See module specification for other years: 2022-23

## Module summary

This module allows you to take all the physics and mathematical skills and knowledge you have acquired in the previous years and apply them to practical physical systems - typically stars. You will begin from a simple perspective to solve practical problems and, as needed, apply more rigorous physical models to find solutions. For example, you can calculate from a simple model and basic physics what the interior temperature of the Sun should be to fuse two protons if these protons fused when they were in contact at about 1 femtometre. You could then check the answer with your intuition, realise it is wrong, and improve it with a semiclassical calculation using the deBroglie wavelength. Finally, the physics and mathematics of sub-barrier fusion will be correctly applied to more fully understand stellar fusion and energy generation.

## Related modules

• None

### Prohibited combinations

• None

Please note, students taking this module should have completed the modules listed a prerequisites (Electromagnetism and Optics - PHY00002I and Mathematics II PHY00030I) or the appropriate equivalent modules.

## Module will run

Occurrence Teaching period
A Spring Term 2021-22

## Module aims

You will take all the physics and mathematical skills and knowledge you have acquired in the previous years and apply them to practical physical systems - typically stars. Your knowledge of the underlying fundamental physics, ability to create simple models and apply theories, and experience with solving quantifiable problems will be used to explore some of the most interesting aspects of stellar evolution, stellar structure, and nucleosynthesis. There is a balance between physics and astrophysics throughout this module.

## Module learning outcomes

• Describe and apply the physical principles underlying gravitational collapse of a dust cloud to form a protostar.
• Describe and derive aspects of energy production and heat transport mechanisms within the stellar interior.
• Describe stellar evolution to and from the main sequence and the conditions of hydrostatic equilibrium.
• Calculate fusion rates and describe element synthesis within stellar environments as well as explain the abundance of elements within the universe.
• Describe the endpoints of stellar evolution as a function of stellar mass.
• Calculate and apply the appropriate classical or relativistic kinematics as well as the ideal or quantum mechanical gas description to the electron and ion components of the stellar interior.

## Module content

Syllabus

• Big Bang nucleosynthesis and gravitational contraction – The synthesis of light elements and hydrostatic equilibrium of non-relativistic and ultra-relativistic particles.
• Star Formation and the Sun– The Jean’s Criteria, contraction of a protostar, conditions for stardom, pressure, density, temperature, and solar radiation.
• Links to radiation transport laser plasma measurements of opacities relevant to stellar physics
• Stellar Nucleosynthesis and Stellar Life Cycles – Stellar mass and the extent of thermonuclear fusion, burning cycles, neutron capture, the rate and endpoint of stellar evolution, abundances of chemical elements.
• Hertzsprung-Russell Diagram – Luminosity, surface temperature, star clusters, tracks and variable stars.
• Properties of Matter within stars – Ideal gas law, density of states, internal energy, pressure, ideal classical gas, electrons in stars, degenerate electron gases, density-temperature diagram.
• Properties of Radiation within stars – Photon gas, radiation pressure, the Saha Equation, ionization in stars and stellar atmospheres, pair production and photodisintegration.
• Heat transfer in stars – heat transfer via random motion of particles and photons, convection, temperature gradients in stars.
• Thermonuclear fusion in stars – barrier penetration, cross sections, reaction rates, H burning, the p-p chain, CNO cycle, He burning, C production and consumption, advanced burning to Fe-Ni region.
• Stellar structure– pressure, temperature and density inside stars, Modelling the Sun, minimum and maximum masses of stars.
• Endpoints of stellar evolution– white dwarfs, collapse of stellar cores, neutron stars, black holes.
• Helioseismology– pressure and gravity waves, normal modes of oscillation, observations of our Sun from Earth and satellite missions.

Lecture notes
Students are expected to take their own notes during lectures. A set of skeleton notes will be made available online at the end of the course.

## Assessment

Task Length % of module mark
Essay/coursework
The Physics of Stars Assignment 1
N/A 40
Essay/coursework
The Physics of Stars Assignment 2
N/A 60

None

### Reassessment

Task Length % of module mark
Essay/coursework
The Physics of Stars Assignment 1
N/A 40
Essay/coursework
The Physics of Stars Assignment 2
N/A 60

## Module feedback

Our policy on how you receive feedback for formative and summative purposes is contained in our Department Handbook.