Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 13 The contents of the Universe – the grand design
- 14 Aspects of stellar evolution relevant to high energy astrophysics
- 15 Dead stars
- 16 Accretion power in astrophysics
- 17 Interstellar gas and magnetic field
- 18 Synchrotron radiation and the radio emission of the Galaxy
- 19 The origin of the electron energy spectrum in our Galaxy
- 20 The origin of high energy protons and nuclei
- 21 The acceleration of high energy particles
- Appendices – astronomical nomenclature
- Further reading and references
- Index
15 - Dead stars
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- 13 The contents of the Universe – the grand design
- 14 Aspects of stellar evolution relevant to high energy astrophysics
- 15 Dead stars
- 16 Accretion power in astrophysics
- 17 Interstellar gas and magnetic field
- 18 Synchrotron radiation and the radio emission of the Galaxy
- 19 The origin of the electron energy spectrum in our Galaxy
- 20 The origin of high energy protons and nuclei
- 21 The acceleration of high energy particles
- Appendices – astronomical nomenclature
- Further reading and references
- Index
Summary
The formation of dead stars
The types of stars described in Chapters 13 and 14 are held up by the thermal pressure of hot gas, the source of energy to provide the pressure being nuclear energy generation in their cores. As evolution proceeds off the main sequence, up the giant branch and towards the final phases when the outer layers of the star are ejected, the nuclear processing continues further and further along the route to using up the available nuclear energy resources of the star. The more massive the star, the more rapidly it evolves and the further it can proceed along the path to the formation of iron, the most stable of the chemical elements. An intriguing question is whether or not the star is disrupted by the various ‘flashes’ which are expected to take place as new regimes of nucleosynthesis are switched on, for example, at the points E and G in Fig. 13.19. In the most massive stars, M ≥ 10M⊙, it is likely that the nuclear burning can proceed all the way through to iron, whereas, in less massive stars, the oxygen flash, which occurs when core burning of oxygen begins, may be sufficient to disrupt the star. In any case, at the end of these phases of stellar evolution, the core of the star runs out of nuclear fuel, and it collapses until some other form of pressure support enables a new equilibrium configuration to be attained.
The possible equilibrium configurations which can exist when the star collapses are white dwarfs, neutron stars and black holes.
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- High Energy Astrophysics , pp. 68 - 132Publisher: Cambridge University PressPrint publication year: 1994
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