- Welcome to the OUR UNIVERSE (SPA4101) Home Page
This module provides an introductory survey of our knowledge of the Universe. It will explain the evolution of the Solar System, Stars, Galaxies and the Universe at large - through the principles of the laws of Physics
Emergency changes to the module, its teaching, and/or its assessment, which may come about through external factors (e.g., the weather) will appear here. Students are expected to check this page regularly.
Kaufmann, W.J. & Freedman, R.A. Universe W.H. Freeman, (6th edition, 2001) ISBN 0-7167-4647-6 Chaisson, E. & McMillan, S. Astronomy Today Prentice Hall, (2001) ISBN 0-13-091542-4
AIMS AND OBJECTIVES
The aims of the course are:
- To acquaint students with a wide-ranging view of the universe from the solar system to stars, the Galaxy, its constituents and to the universe beyond our Galaxy;
- to inform them of the role played by the known laws of physics in our understanding of the observed universe;
- to train them to use astronomical information sources, especially those on the web providing services both to the astronomer and the layman;
- to provide the opportunity for students to gain experience of writing and talking about astronomy at a level either appropriate to a scientist or a layman
By the end of the course students should
- have gained a familiarity with the constituents of the observed universe;
- appreciate the important part played by the laws of physics in making observations, and interpreting and understanding them;
- be able to explain the different types of information obtainable from observations across the entire wavelength range from gamma rays to radio waves;
- have gained a familiarity with astronomical resources on the web and in the library;
- be able to give written accounts and and oral presentations on topics related to the course at a level appropriate to a particular audience by using web and library resources.
1. The Universe: An overview.
Using multimedia sources to illustrate the constituents of the universe. Space and time scales, the role of physical laws and the importance of multi-wavelength observations provide common threads running through this broad-brush presentation as well as throughout the course.
- The Solar System.
Planets, comets, and other smaller constituents discussed using current and recent space missions, illustrating both the observed properties and the importance of the scientific approach. Topics discussed will include methods of dating, the conditions for the existence of life on the earth and the possibility of its occurrence on other planets; the search for life within and outside the solar system. The formation of planets and the evolution of the solar system.
- The Sun.
The role of physics in observing the sun and inferring some of its properties: spectra and Kirchoff's spectral laws for the formation of spectral lines, black body spectrum (Planck's law), solar Luminosity, mass, radius and chemical constitution; the abundance of elements in the cosmos. Solar atmospheric phenomena and solar weather (the SOHO mission); its effect on the earth. The solar interior, hydrostatic stability using simple physical arguments to estimate the internal pressure and temperature. Energy source for the sun is nuclear fusion in the hot, dense core; energy transport in the sun.
A review of the range of particle and radiation fluxes reaching the earth, their sources and the means of detecting them. Electromagnetic radiation: radio, infrared, visible, ultraviolet, X-ray and gamma radiation. Ground based optical, infrared and radio telescopes; space telescopes. Cosmic rays.
- Light from the Stars.
Colours, spectra, temperatures, masses and radii of stars: the Hertzsprung-Russell (HR) diagram, the main-sequence (MS), mass-Luminosity and radius-Luminosity relation for MS stars. Description of different stellar types: red giants, pre- and post-MS stars, the horizontal branch, white dwarfs, planetary nebulae and mass loss in general - supernovae. Variable stars.
- Pre-MS evolution: Star Formation.
An illustrated account of ideas and evidence for star formation in the interstellar medium. Gravity as a driving force for star formation and energy generation. Mass outflows, magnetic fields, circumstellar matter, planetary formation. The search for extra-solar planets.
- Evolution on the MS.
The equations of stellar structure discussed qualitatively to obtain estimates of the mass-Luminosity relation and lifetimes of stars on the MS. Nuclear fusion processes: the pp chains and the CN cycle; detecting neutrinos from the sun and the solar neutrino problem; Neutrino astronomy.
- Leaving the MS: post-MS evolution.
An end to hydrogen fusion; a description of predicted evolution away from the main sequence through various stages of nuclear fusion. The inevitability of an end to energy generation by nuclear fusion: the binding energy versus nuclear mass plot; fusion contrasted with fission; how are elements beyond iron made? Evidence for the theoretical description of stellar evolution: galactic and globular clusters. Stellar collapse and supernovae.
- Final stages of Stellar Evolution: collapse under gravity.
Supernovae: theory and observations. The observed properties of the white dwarf star Sirius B: density above a million times that of water. White dwarf stability and the physics of electron quantum mechanical degeneracy pressure: a maximum white dwarf mass, the Chandrasekhar limit of 1.4 solar masses. Evidence for the stability and cooling of white dwarf stars. The collapse of heavier stars, the Oppenheimer-Volkov argument for the loss of electrons by inverse beta decay, the consequent formation of unstable neutron-rich nuclei, neutron drip and the formation of a neutron gas causing degeneracy pressure and stability for masses up to 2 or 3 solar masses: Neutron stars. Pulsars and their properties: evidence for neutron stars. For heavier stars collapse under gravity cannot be prevented: a black hole is formed; the Schwartschild radius.
- Black Holes:
Discussion of some of the properties of black holes including accretion of matter, X-ray emission and X-ray astronomy (the current Chandra and XMM space observatories). Efficiency of energy generation by accretion onto black holes - a probable power source for active galactic nuclei (AGN). The quantum vacuum and Hawking's exploding black holes.
- Galaxies and the Universe:
Types of galaxies: spiral, elliptical, and irregular galaxies; radio galaxies, quasars, active galactic nuclei (AGN). The energy sources for AGN. Galaxy clusters; problems of distance measurement; evolution of galaxies. Dynamics of galaxies and galaxy clusters: dark matter.
The expansion of the universe; the red-shift distance relation (Hubble's law) and its interpretation. Extrapolation backwards in time: the age of the universe. The early hot big bang universe; radiation dominance, light element nucleosynthesis; decoupling and cooling of the radiation. Observation of the Cosmic Microwave Background Radiation (CMBR) and its interpretation. Density of the univese, dark matter and the formation of galaxies. The very early universe and inflation.
- Current developments.
Several topics of current interest will be discussed each year to round off the course. This will be followed with a discussion of wider issues such as the public perception of the science of astronomy, its funding and its use in providing both an introduction to science in general and its intellectual and practical role.
The 8 weekly pieces of coursework will be published here one week before the submission deadline (with the first appearing during Week 1 for submission in Week 2). You should answer the exercise class question during the exercise class with the assistance of the teaching assistant. You should answer and submit all of the homework questions, but please note that you will receive marks and detailed feedback only for the starred questions. The coursework deadline is 2pm on Friday of each week.
The solutions to the each piece of coursework will be published here two days after its submission deadline.
Coursework deadlines Wednesdays at 1600 of Weeks 2, 3, 4, 5, 6, 8, 9, 10 and 11