AN INTRODUCTION TO NUCLEAR ASTROPHYSICS GEOPHYSICS AND ASTROPHYSICS MONOGRAPHS AN INTERNATIONAL SERIES OF FUNDAMENTAL TEXTBOOKS Editor B. M. MCCORMAC, Lockheed Palo Alto Research Laboratory, Palo Alto, Calif, U.S.A. Editorial Board R. GRANT ATHAY. High Altitude Observatory, Boulder, Colo., U.S.A. W. S. BROECKER. Lamont-Doherty Geological Observatory, Palisades, New York, U.S.A. P. 1. COLEMAN, JR., University of California, Los Angeles, Calif, U.S.A. G. T. CSANADY, Woods Hole Oceanographic Institution, Woods Hole, Mass., U.S.A. D. M. HUNTEN, University o/Arizona, Tucson, Ariz., U.S.A. C. DE JAGER, The Astronomical Institute, Utrecht. The Netherlands J. KLECZEK, Czechoslovak Academy olSciences, Ondtejov, Czechoslovakia R. LUST, President Max-Planck Gesellschaltfur Forderung der lVissenschalten, Munchen, F.R.G. R. E. MUNN, University olToronto, Toronto, Ont., Canada Z. SVESTKA, The Astronomical Institute, Utrecht, The Netherlands G. WEILL, Service d'Aeronomie, Verrieres-Ce, Buisson, France VOLUME 18 AN INTRODUCTION TO NUCLEAR ASTROPHYSICS The Formation and the Evolution of Matter in the Universe JEAN AUDOUZE lnstitut d'Astrophysique de Paris, France and SYLVIE VA UCLAI R DAPHE, Ohservatoire de Meudon, France and lnstitut d'Astrophysique, Paris D, REIDEL PUBLISHING COMPANY DORDRECHT: HOLLAND/BOSTON: U.S.A. LONDON: ENGLAND Library of Congre~ Cataloging in Publication Data Audouzc. Jean An introduction to nuclear astrophysics. (Geophysics and astrophysics monographs; v. 18) En!. and updated translation of L'Astrophysique nuclt\aire. Includes bibliographies and index. \. Nuclear astrophysics. I. Vauclair, Sylvie, joint author. II. Title. III. Series. QB464.A9313 1979 523.01'9'7 79-20752 ISBN-13: 978-90-277-1053-6 e-ISBN-13: 978-94-009-9477-5 DO I: 10.1007/978-94-009-9477-5 Published by D. Reidel Publishing Company, P.O. Box 17. Dordrecht, Holland Sold and distributed in the U.S.A., Canada, and Mexico by D. Reidel Publishing Company, Inc. Lincoln Building. 160 Old Derby Street, Hingham, Mass. 02043, U.S.A. All Rights Reserved Copyright © 1980 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint of the hardcover 1st edition 1980 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner TABLE OF CONTENTS FOREWORD IX INTRODUCTION xi XXI ACKNOWLEDGEMENTS CHAPTER I / THE OBSERVATIONAL BASIS OF NUCLEAR ASTROPHYSICS 1.1. The Importance of the Four Fundamental Interactions 1 1.2. A Brief Description of the Observed Universe 3 CHAPTER II / THE EVOLUTION OF MATTER IN THE UNIVERSE 21 11.1. The Origin of the Universe 21 11.1.1. The Hadron Era 24 II.I.2. The Lepton Era 24 II. 1.3. The Radiation Era 24 11.1.4. The Stellar Era 25 II.2. Stellar Evolution 26 II.2.1. The Hertzsprung-Russell Diagram 26 11.2.2. Stellar Evolution 28 CHAPTER III/THE CHEMICAL COMPOSITION OF THE OBSERVABLE UNIVERSE 33 IIl.1. Techniques for Abundance Determination 33 IIl.I.I. The Direct Methods 33 III. 1.2. The Indirect Methods 33 111.2. The Abundances of the Elements in the Universe 38 111.3. Main-Sequence Peculiar Stars 42 CHAPTER IV / THERMONUCLEAR REACTIONS AND NUCLEAR REACTIONS IN STELLAR INTERIORS 45 IV.1. Nuclear Reactions: Generalities 45 IV.2. Nuclear Reaction Rates 46 IV.3. Hydrogen Burning 51 IV.3.1. The Proton-Proton Chain or PPI Chain 51 VI TABLE OF CONTENTS IV.3.2. The Proton Chains with a He Catalyst, or PPII and PPIII Chains 53 IV.3.3. The CNO Cycles 54 IVA. Helium Burning 55 IV.5. Hydrostatic C, 0, and Si Burning 57 IV.6. Conclusion 58 CHAPTER V / EXPLOSIVE NUCLEOSYNTHESIS IN STARS 60 V.l. Supernovae 60 V.l.l. The Fe Photodisintegration Mechanism 64 V.l.2. The C Detonation Mechanism 64 V.I.3. The Neutrino Transport Mechanism 65 V.lA. Deceleration of the Central Pulsar 65 V.2. Other Explosive Objects or Explosive Stages 67 V.2.I. The Helium Flashes 67 V.2.2. The Novae Outbursts 68 V.2.3. Explosions of Supermassive Stars 69 V.3. The Explosive Nucleosynthesis 70 VA. The Main Results of the Explosive Nucleosynthesis 74 VA.I. Explosive Burning in H and He Burning Zones 74 VA.2. Explosive Nucleosynthesis in C, 0, and Si Burning Zones 75 CHAPTER VI/FORMA TION OF THE HEA VY ELEMENTS: S, r, AND p PROCESSES 80 VI.l. Abundances of the Heavy Elements-Processes of Neutron Capture 81 VI.2. Neutron Capture Reactions 85 VI.3. The S Process 86 VI.3.I. The Main Neutron Sources for the S Process 86 VI.3.2. The s Process Nucleosynthesis 87 VIA. The r Process 89 VI. 5. The p Process 92 VI.5.I. Weak Interaction Mechanism 93 VI.5.2. Spallation Reactions 93 VI.5.3. Thermonuclear Reactions 94 CHAPTER VII / NUCLEOSYNTHESIS OF THE LIGHT ELEMENTS 97 VII.1. The Abundance of the Light Elements 97 VII.2. The Spallation Reactions 100 VIl.3. Production of Li, Be, B, by the Galactic Cosmic Rays 102 VIlA. Light Element Production in Stellar Objects 108 VIlA.i. Light Element Production in Supernovae Explosions 108 VII.4.2. Other Stellar Sites to Produce 7Li 109 VII.5. The Big Bang Nucleosynthesis 109 TABLE OF CONTENTS vii VII.5.l. The Basic Assumptions llO VII.5.2. The Standard Model 110 VII.6. Conclusion 113 CHAPTER VIII! NUCLEOCHRONOLOGIES AND THE FORMATION OF THE SOLAR SYSTEM 115 VIII. I. Astronomical Chronologies 116 VIII.2. Nucleochronologies 118 VIII.2.1 Duration of the Nucleosynthesis: Long Lifetime Radionuclides 121 VIII.2.2. The Short Lived Isotopes (AT» 1) 123 VIII. 3. Isotopic Anomalies in Carbonaceous Chondrites 128 VIII.4. The Astrophysical Implications of the Anomalies 132 VIII.5. Conclusion 135 CHAPTER IX / CHEMICAL EVOLUTION OF GALAXIES 137 IX.l. Observational Abundance Distribution 137 IX.2. The Ingredients of the Galactic Chemical Evolution 140 IX.2.l. Parameters Related to the Stellar Populations 140 IX.2.2. Dynamical Effects: Inflow of External Gas; Inhomogeneities 143 IX.3. Evolution of the Solar Neighborhood 144 IX.3.l. The Simple Model 144 IX.3.2. Further Models of Evolution 147 IX.3.2.l. Variable Initial Mass Function Models (VIM F) 147 IX.3.2.2. Prompt Initial Enrichment (PIE model) 147 IX.3.2.3. Metal Enhanced Star Formation (MESF) 147 IX.3.2.4. Accretion or Infall of External Gas 148 IX.4. Numerical Models with No Instant Recycling 149 IX.5. Conclusion: Chemical Evolution of Galaxies 152 CONCLUSION 155 APPENDIX 159 Appendix AI. Some Fundamental Constants 159 Appendix All. Some Astronomical Constants 159 Appendix AlII. Some Quantities Associated with One Electron-Volt 160 Appendix B. Atomic Mass Excesses 161 INDEX OF SUBJECTS 165 FOREWORD This textbook represents an extended version of a short monograph I'Astrophysique Nucleaire written by both of us and published by les Presses Universitaires de France in 1972. The text of the present work has been enlarged (the material from the French monograph represents about 33% of this book) and updated because of the impressive progress achieved in this fast moving field. This book, which is also largely based on lectures presented to many students, mainly those of Ecole Polytechnique for Jean Audouze and those of Universite Paris VII for Sylvie Vauclair, is intended for under­ graduate (astronomy major or non major) and graduate students interested in Astro­ physics and also to a more general audience since no specific expertise in astronomy, physics and mathematics is required to fruitfully read this text. We are both grateful to our many students who have been attending our lectures and forced us to shape the material presented here. We acknowledge the invaluable help of Mmes Annie Dao, Marie-Claude Pantalacci and Madeleine Steinberg in the material presentation of the text. We would like to thank Dr. Billy McCormac, the editor of the collection, and Dr. Gerard Vauclair for their critical comments on the manuscript. Last but not least, we thank the D. Reidel Publishing Company for their patience. JEAN AUDOUZE AND SYLVIE VAUCLAIR Paris and M eudon December 1978 ix INTRODUCTION Man has always been intrigued by his environment and by his relationship with it. During the first ages of Humanity this relationship was described or debated by religions or superstitions and not by what we designate under the name of sciences. But, since the very first ages, men have adopted the scientific attitude which is to describe an environment in terms of interactions between the various constituents of what is believed to be the Universe. This is why astronomy, which tries to describe the whole Universe and to understand its evolution, has been the first science to emerge from the human mind. During antiquity men already knew the difference between stars and planets. More recently, the important (and controversial at the time) contributions of Copernicus and Galileo (to choose among the most famous astronomers) are quite well known. Man has spent more time penetrating the nature of the microcosm than making a rough description of the macrocosm. If the word and the concept of the atom is indeed ancient (atoms were imagined by Greek philosophers such as Democritus), their study in the scientific sense has only been initiated during the 19th century: one must wait for the works of Thompson and Rutherford to get into the tremendous and complex world of the atoms themselves which are composed of almost empty spaces where electrons jingle around extremely small and dense nuclei. At present, many physicists devote their scientific endeavors to try and discover what is the actual basic stone (if any!) of our Universe: the atomic nuclei are constituted by nucleons (protons and neutrons).