Book contents
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Part I Astronomical background
- Part II Physical processes
- Part III High energy astrophysics in our Galaxy
- 12 Interstellar gas and magnetic fields
- 13 Dead stars
- 14 Accretion power in astrophysics
- 15 Cosmic rays
- 16 The origin of cosmic rays in our Galaxy
- 17 The acceleration of high energy particles
- Part IV Extragalactic high energy astrophysics
- Appendix: Astronomical conventions and nomenclature
- Bibliography
- Name index
- Object index
- Index
13 - Dead stars
from Part III - High energy astrophysics in our Galaxy
Published online by Cambridge University Press: 05 June 2012
- Frontmatter
- Contents
- Preface
- Acknowledgements
- Part I Astronomical background
- Part II Physical processes
- Part III High energy astrophysics in our Galaxy
- 12 Interstellar gas and magnetic fields
- 13 Dead stars
- 14 Accretion power in astrophysics
- 15 Cosmic rays
- 16 The origin of cosmic rays in our Galaxy
- 17 The acceleration of high energy particles
- Part IV Extragalactic high energy astrophysics
- Appendix: Astronomical conventions and nomenclature
- Bibliography
- Name index
- Object index
- Index
Summary
The stars described in Chap. 3 are held up by the thermal pressure of hot gas, the source of energy being nuclear energy generation in their central regions. As evolution proceeds from the main sequence, up the giant branch and towards the final phases when the outer layers of the giant star are ejected, nuclear processing continues until the available nuclear energy resources of the star are exhausted. The more massive the star, the more rapidly it evolves and the further it can proceed along the path to the synthesis of iron, the most stable of the chemical elements. In the most massive stars, M ≥ 8 M⊙, 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 collapses until some other form of pressure support enables a new equilibrium configuration to be attained.
Possible equilibrium configurations which can exist when the nuclear fuel runs out are as white dwarfs, neutron stars or black holes. In white dwarfs and neutron stars, the star is supported by degeneracy pressure associated with the fact that electrons, protons and neutrons are fermions and so only one particle can occupy any single quantum mechanical state.
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- Chapter
- Information
- High Energy Astrophysics , pp. 378 - 442Publisher: Cambridge University PressPrint publication year: 2011