The Physics of Stars E-Book

A. C. Phillips

• Herausgeber: John Wiley & Sons
• Kategorie: Lebensstil
• Serie: The Manchester Physics Series
• Sprache: Englisch

Seitenzahl: 430

Veröffentlichungsjahr: 2013

Beschreibung

The Physics of Stars, Second Edition, is a concise introduction to the properties of stellar interiors and consequently the structure and evolution of stars. Strongly emphasising the basic physics, simple and uncomplicated theoretical models are used to illustrate clearly the connections between fundamental physics and stellar properties. This text does not intend to be encyclopaedic, rather it tends to focus on the most interesting and important aspects of stellar structure, evolution and nucleosynthesis. In the Second Edition, a new chapter on Helioseismology has been added, along with a list of physical constants and extra student problems. There is also new material on the Hertztsprung-Russell diagram, as well as a general updating of the entire text. It includes numerous problems at the end of each chapter aimed at both testing and extending student's knowledge.

Leseprobe

Contents

Editors’ preface to the Manchester Physics Series

Author’s preface

Author’s preface to the second edition

1 BASIC CONCEPTS IN ASTROPHYSICS

1.1 BIG BANG NUCLEOSYNTHESIS

1.2 GRAVITATIONAL CONTRACTION

1.3 STAR FORMATION

1.4 THE SUN

1.5 STELLAR NUCLEOSYNTHESIS

1.6 STELLAR LIFE CYCLES

1.7 THE HERTZSPRUNG–RUSSELL DIAGRAM

SUMMARY

PROBLEMS 1

2 PROPERTIES OF MATTER AND RADIATION

2.1 THE IDEAL GAS

2.2 ELECTRONS IN STARS

2.3 PHOTONS IN STARS

2.4 THE SAHA EQUATION

2.5 IONIZATION IN STARS

2.6 REACTIONS AT HIGH TEMPERATURE

SUMMARY

PROBLEMS 2

3 HEAT TRANSFER IN STARS

3.1 HEAT TRANSFER BY RANDOM MOTION

3.2 HEAT TRANSFER BY CONVECTION

3.3 TEMPERATURE GRADIENTS IN STARS

3.4 COOLING OF WHITE DWARFS

SUMMARY

PROBLEMS 3

4 THERMONUCLEAR FUSION IN STARS

4.1 THE PHYSICS OF NUCLEAR FUSION

4.2 HYDROGEN BURNING

4.3 HELIUM BURNING

4.4 ADVANCED BURNING

SUMMARY

PROBLEMS 4

5 STELLAR STRUCTURE

5.1 PREAMBLE

5.2 SIMPLE STELLAR MODELS

5.3 MODELLING THE SUN

5.4 MINIMUM AND MAXIMUM MASSES FOR STARS

SUMMARY

PROBLEMS 5

6 THE ENDPOINTS OF STELLAR EVOLUTION

6.1 WHITE DWARFS

6.2 COLLAPSE OF A STELLAR CORE

6.3 NEUTRON STARS

6.4 BLACK HOLES

SUMMARY

PROBLEMS 6

7 HELIOSEISMOLOGY

7.1 INTRODUCTION

7.2 PRESSURE AND GRAVITY WAVES

7.3 WAVES INSIDE THE SUN

7.4 NORMAL MODES OF OSCILLATION

SUMMARY

PROBLEMS 7

HINTS TO SELECTED PROBLEMS

Bibliography

Index

The Manchester Physics Series

General Editors

D. J. SANDIFORD: F. MANDL: A. C. PHILLIPS

Department of Physics and Astronomy,University of Manchester

Properties of Matter

B. H. Flowers and E. Mendoza

Statistical Physics:

Second Edition

F. Mandl

Electromagnetism:

Second Edition

I. S. Grant and W. R. Phillips

Statistics:

R. J. Barlow

Solid State Physics:

Second Edition

J. R. Hook and H. E. Hall

Quantum Mechanics:

F. Mandl

Particle Physics:

Second Edition

B. R. Martin and G. Shaw

The Physics of Stars:

Second Edition

A. C. Phillips

Computing for Scientists:

R. J. Barlow and A. R. Barnett

Computing For Scientists:

J. Lilley

Copyright © 1994, 1990 by John Wiley & Sons, Ltd,The Atrium, Southern Gate, Chichester,West Sussex PO19 8SQ, England

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British Library Cataloguing in Publication Data

A catalogue record for this book is available from the British Library

ISBN 13: 978-0-471-98798-7 (P/B)

ISBN 13: 978-0-471-98797-0 (H/B)

Editors’ preface to the Manchester Physics Series

The Manchester Physics Series is a series of textbooks at first degree level. It grew out of our experience at the Department of Physics and Astronomy at Manchester University, widely shared elsewhere, that many textbooks contain much more material than can be accommodated in a typical undergraduate course; and that this material is only rarely so arranged as to allow the definition of a shorter self-contained course. In planning these books we have had two objectives. One was to produce short books: so that lecturers should find them attractive for undergraduate courses; so that students should not be frightened off by their encyclopaedic size or their price. To achieve this, we have been very selective in the choice of topics, with the emphasis on the basic physics together with some instructive, stimulating and useful applications. Our second objective was to produce books which allow courses of different lengths and difficulty to be selected, with emphasis on different applications. To achieve such flexibility we have encouraged authors to use flow diagrams showing the logical connections between different chapters and to put some topics in starred sections. These cover more advanced and alternative material which is not required for the understanding of latter parts of each volume.

Although these books were conceived as a series, each of them is self-contained and can be used independently of the others. Several of them are suitable for wider use in other sciences. Each Author’s Preface gives details about the level, prerequisites, etc., of his volume.

The Manchester Physics Series has been very successful with total sales of more than a quarter of a million copies. We are extremely grateful to the many students and colleagues, at Manchester and elsewhere, for helpful criticisms and stimulating comments. Our particular thanks go to the authors for all the work they have done, for the many new ideas they have contributed, and for discussing patiently, and often accepting, the suggestions of the editors.

Finally, we would like to thank our publishers, John Wiley & Sons Ltd, for their enthusiastic and continued commitment to the Manchester Physics Series.

D. J. SandifordF. MandlA. C. PhillipsFebruary 1997

Author’s preface

Astrophysics is of natural interest to students and provides an ideal framework for demonstrating the power and elegance of physics. It is not surprising, therefore, that astrophysics is playing an increasing part in physics education. Despite this, there is a shortage of suitable textbooks for advanced undergraduates and beginning graduate students. For the most part, existing books are either too elementary and descriptive, or too technical and encyclopaedic.

This book is based on lectures prepared for a one-semester course on stars for fmal-year undergraduates at Manchester University. To a large extent, the selection of topics covered has been based on a personal judgement as to whether the topic is important and whether it is also interesting to understand in terms of basic physics. The book is unusual in two respects.

First, there is a strong emphasis on explaining the underlying fundamental physics. Second, simple theoretical models are used to illustrate clearly the connections between fundamental physics and stellar properties. The overall aim is a self-contained, concise explanation of some of the most interesting aspects of stellar structure, evolution and nucleosynthesis.

In organizing the material in this book, I have recognized that the reader’s motivation to understand physics is enhanced if the astrophysical application is near at hand and that an understanding of astrophysics requires a clear and concise reminder of physical principles. Thus, I have attempted to maintain a balance between physics and astrophysics throughout.

The first chapter introduces basic astrophysical concepts using elementary physical ideas which should be familiar to students pursuing a course on stars. Subsequent chapters rely on more advanced physical ideas which are normally met in the latter part of an undergraduate course. These ideas are carefully explained before they are applied. The properties of matter and radiation are considered in Chapter 2, heat transfer in Chapter 3, thermonuclear fusion in Chapter 4, stellar structure in Chapter 5, and the endpoints of stellar evolution, namely white dwarfs, neutron stars and black holes, in Chapter 6. At the end of each chapter there are a number of problems aimed at testing understanding and extending knowledge. Hints for the solution of these problems are given at the end of the book.

In preparing the manuscript I have consulted many books and articles on astrophysics, particularly those listed in the bibliography. It is important to mention here a subset of books and articles which have been particularly influential. My interest in stellar physics was initially stimulated many years ago by the deep insight and directness of the articles by Salpeter, Weisskopf and Nauerberg. I have learnt much from two superb books: Black Holes, White Dwarfs, and Neutron Stars by Shapiro and Teukolsky and Neutrino Astrophysics by Bahcall. In addition, Clayton’s elegant article on Solar Structure Without Computers had a strong influence in Chapter 5. I have also found very useful the wealth of detail in Cauldrons in the Cosmos, Nuclear Astrophysics by Rolfs and Rodney, and in Astrophysics I, Stars by Bowers and Deeming.

Finally, I would like to express my thanks to colleagues at Manchester University. First, Franz Kahn and Franz Mandl read the early, primitive draft of the book, and their envouragement and help led me to take the idea of writing this book seriously; in particular, Franz Mandl’s advice as Editor of the Manchester Physics Series was invaluable. Second, Judith McGovern and Mike Birse were very patient with me when I sought their help after doing stupid things with the word processor.

A. C. PhillipsMay, 1993

Author’s preface to the second edition

When the First Edition of Physics of Stars was reviewed in The Observatory by Andrew Collier Cameron, he began his review thus:

Stellar structure can be a tough subject to teach and to learn at undergraduate level. It draws on every branch of physics that the undergraduate has encountered in the preceding years, and frequently a few additional ones for good measure. The whole lot is then transplanted into the often bizarre regimes that prevail in stellar interiors.

It is small wonder that many of those who attend a course on stellar structure, or who return to it after some years in order to teach it for the first time, soon develop the nasty feeling that if they ever understood the physics concerned, that understanding has evaporated. This is partly because many of the relevant areas of physics are taught in completely different contexts. Thermodynamics, for example, is often confined to its historical context, in the nineteenth-century world of pistons and steam. Its real physical origins in statistical mechanics are delivered separately in the abstract world of phase space.

Phillips has written a book which turns this whole approach on its head. The title is well-chosen; this is a textbook covering the branches of physics that are important in stellar structure.

The new edition retains this emphasis on developing an understanding of fundamental physics before considering key aspects of stellar structure, evolution and nucleosynthesis. The main changes are as follows:

The discussion of the Hertzsprung-Russell diagram at the end of Chapter 1 has been extended.

A new chapter on Helioseismology has been added, but in doing so I have taken care to develop an understanding of the physics of wave propagation before discussing the normal modes of vibration of the sun.

The number of the problems at the end of the chapters has been significantly increased.

A C PhillipsNovember 1998

1

Basic concepts in astrophysics

The aim of this book is to explore the properties of stellar interiors and hence understand the structure and evolution of stars. This exercise is largely based on the application of thermal and nuclear physics to matter and radiation at high temperatures and pressures. However, before developing and applying this physics it is useful to consider the subject as a whole using elementary physics. In this brief and rapid overview we shall introduce some concepts which are fundamental to stellar evolution, fix the order of magnitude of some important astrophysical quantities and identify the basic observational information on stars. Many of the topics mentioned are covered in more detail later in the book and in the references listed at the end of the book. We begin by considering the processes which produced the raw material used in the construction of the first stars.

1.1 BIG BANG NUCLEOSYNTHESIS

To a first approximation matter in the universe consists of hydrogen and helium, with a smidgen of heavier elements such as carbon, oxygen and iron. It is now recognized that the bulk of this helium was produced by nuclear reactions which occurred during the first few minutes of the universe, a process called primordial or big bang nucleosynthesis. We shall begin this introductory chapter by giving a very brief outline of big bang nucleosynthesis so that the reader is aware of the origin and nature of the raw material used in the construction of the first stars.

A brief history of the universe

In order to understand the history of the universe it is necessary to account for two important facts regarding the present universe: firstly the universe is expanding in such a way that if we extrapolate back in time it appears that the universe had infinite density some 10 to 20 billion years ago. Secondly the whole of space is filled with a thermal radiation at a temperature of about 3 K, the cosmic microwave background radiation discovered by Penzias and Wilson in 1965. These facts are consistent with the idea that the universe began with a sudden decompression, a big bang.

The big bang is not a local phenomenon with matter being expelled in all directions from a point in space. The big bang happened simultaneously everywhere in space. Everywhere was a point at the time of the big bang if the universe is closed, i.e. a finite volume of space with no boundary. But if the universe is open, the big bang occurred all over a space of infinite extent. According to the standard model of the big bang, the universe developed along the following lines:

Nanoseconds after the big bang the universe was filled with a gas of fundamental particles: quarks and antiquarks, leptons and antileptons, neutrinos and antineutrinos, and gluons and photons. When the temperature fell below 10 K, the quarks, antiquarks and gluons disappeared, annihilating and transforming into less massive particles. Fortunately, because the number of quarks slightly exceeded the number of antiquarks, a few quarks were left behind to form the protons and neutrons present in today’s universe. The heavier leptons and antileptons were also annihilated as the temperature fell.