AN INTRODUCTION TO COSMOCHEMISTRY CHARLES R. COWLEY Professor of Astronomy, University of Michigan CAMBRIDGE UNIVERSITY PRESS
Foreword V a % e x i 1 Overview 1 1.1 The Scope of Cosmochemistry 1 1.2 Cosmochemistry and the Four Physical Sciences 2 1.3 A Standard Abundance Distribution 3 1.4 The Chemical History of Planetary Material 6 1.5 Abundances Beyond the Solar System 7 1.6 Two Approaches to Cosmochemistry 8 2 Minerals: An Introduction to the Nomenclature and Chemistry 9 2.1 Introduction 9 2.2 Mineralogy 11 2.3 Some Useful Concepts from Crystallography 12 2.4 A Simplified Mineral Classification 14 2.5 The Common Minerals of Cosmochemistry 16 2.5.1 Oxides 18 2.5.2 The Olivines 19 2.5.3 The Pyroxenes 19 2.5.4 The Feldspars '' 21 2.6 Mineralogy as a Clue to History: The Bowen Reaction Series; Paragenesis 22 2.7 Problems 26 3 A Brief Introduction to Petrology 27 3.1 Preliminary Remarks 27 3.2 The Classification of Igneous Rocks 28 3.3 Some Terminology Related to the Texture of Rocks 30 3.4 Basalts, Gabbros, and Anorthosites 31 3.5 Phase Diagrams 31 3.6 Formation of the Lunar Highlands: A Petrological Exercise 35 3.7 Problems 38 4 A Resume of Thermodynamics and Statistical Mechanics 39 4.1 Introductory Remarks 39 4.2 Systems, States, and Variables 39 4.3 Additional State Functions and the Laws of Thermodynamics 41 4.4 How to Tell the Direction of a Chemical Reaction 44
viii 4.5 Calculation of AG; Standard States 46 4.6 Free Energy Changes At Arbitrary Pressures 48 4.7 Heat Capacities 52 4.8 Chemical Equilibrium 52 4.9 Statistical Mechanics: Distributions 54 4.10 Boltzmann's postulate: the Connection Between W and the Entropy S 57 4.11 The Particle in a Box: Quantum Cells for Free Particles 59 4.12 Chemical Equilibrium and Statistical Mechanics 61 4.13 Problems 62 5 Condensation Sequences and the Geochemical Classification of the Elements 64 5.1 The Concept of Geochemical Classification 64 5.2 The Siderophile-Lithophile Distinction 68 5.3 The Problem with the Chalcophiles 71 5.4 Molecular Equilibria in the Gas Phase 71 5.5 The Condensation of Solids 76 5.6 The Geochemical Classes of Volatile and Refractory 80 5.7 The Geochemistry of Trace Elements: Ionic Substitution 82 5.8 Problems 88 6 The Theory of the Bulk Composition of the Planets 89 6.1 Geophysical Constraints 89 6.2 Earth Models 91 6.3 The Moon and Terrestrial Planets 94 6.4 The Jovian Planets 96 6.5 A Zero-Order Model for the Solar Nebula 97 6.6 Equilibrium and Disequilibrium Condensation 99 6.7 The Condensation Sequences of Lewis and Coworkers 101 6.8 Difficulties with the Condensation Sequences 104 6.9 Problems 108 7 Meteorites and the Standard Abundance Distribution (SAD) 109 7.1 An Overview 109 7.2 Meteorite Ages 112 7.3 Meteorites and the SAD 116 7.4 The SAD and Nuclear Processes: Overview 119 7.5 Problems 123 8 An Introduction to Isotope Geology with an Emphasis on Meteorites 125 8.1 Introduction 125 8.2 Rubidium-Strontium Dating; Sample and Model Ages 125 8.3 Evolution of the Initial Ratio: ( 87 Sr/ 86 Sr) 0 128 8.4 Further Remarks on Radioactive Dating 130 8.5 Stable Isotope Geology 131 8.6 Oxygen Anomalies and the Refractory Inclusions of Meteorites 135 8.7 Isotopic Anomalies in the Noble Gases 136 8.8 Aluminum-26 in the Early Solar System 144 8.9 The Nature of the Allende Inclusions 147 8.10 Problems 148
ix 9 Some Concepts from Nuclear Physics 150 9.1 Introductory Remarks 150 9.2 The Semi-empirical Mass Formula 150 9.3 The One-Particle or Shell Model of the Nucleus 157 9.4 The Classical Forms of Radioactivity, and Fission 165 9.5 Nuclear Reactions and Their Rates 171 9.6 Problems. 184 10 Energy Generation in Stars and Nucleosynthesis 186 10.1 Introduction 186 10.2 The Burning of Hydrogen and Helium 187 10.3 Carbon, Oxygen, and Neon Burning 190 10.4 Silicon Burning, Equilibrium, and Quasi-Equilibrium Processes 191 10.5 The Problem of the Light Nuclei: Li, Be, and B 199 10.6 Cosmic Rays and Abundances of LiBeB 203 10.7 Cosmological Production of the Light Elements 206 10.8 Synthesis of Nuclides Beyond the Iron Peak: the s-process 214 10.9 The Classical r-process 220 10.10 Additional Mechanisms for the Production of Elements Beyond the Iron Peak 224 10.11 Supernovae and Supernova 1987A 226 10.12 Problems, 228 11 Atomic and Molecular Spectra 230 11.1 Introductory Remarks 230 11.2 Atomic Spectra: The Nomenclature of LS Coupling 230 11.3 A Brief Description of the Data Tables 234 11.4 Diatomic Molecules: Rotation and Vibration 237 11.5 Diatomic Molecules: Electronic Structure and Wavelengths 243 11.6 Rotational Structure of Symmetrical Top Molecules 249 11.7 Rotational Structure of Asymmetrical Top Molecules 251 11.8 Nuclear Effects in Atomic and Molecular Spectra: Hyperfine Structure 253 11.9 Problems 258 12 The Analysis of Stellar Spectra 260 12.1 The Identification of Lines in Stellar Spectra 260 12.2 Details of Identification Work 263 12.3 The Analysis of Stellar Spectra: Overview 265 12.4 The Slab Model 270 12.5 Details of the Line Absorption Coefficient 275 12.6 Doppler Broadening of Spectral Lines 276 12.7 The Curve of Growth for Equivalent Widths 278 12.8 Details of the Curve of Growth 281 12.9 The Method of Spectral Synthesis 284 12.10 Problems 287
13 The Chemistry of Stars and Stellar Systems 289 13.1 The General Framework 289 13.2 Spectral Classification 290 13.3 The Hertzsprung-Russell (H-R) Diagram 292 13.4 Stellar Abundances 297 13.4.1 Population-Related Abundance Patterns 297 13.4.2 Abundance Variations Attributed to In Situ Nucleosynthesis 305 13.4.3 Abundance Variations Attributed to Chemical Fractionations 308 13.5 Problems 314 14 Cold, Non-stellar Material in Galaxies 315 14.1 Introduction 315 14.2 Molecular Clouds 322 14.3 The Theory of Interstellar Chemistry 329 14.4 Interstellar Grains: Optical Properties 337 14.5 Interstellar and Circumstellar Features 344 14.6 The Formation of Dust 352 14.7 Problems 357 15 Emission-Line Regions and their Chemical Abundances 359 15.1 Emission Regions 359 15.2 Planetary and Diffuse Nebulae: The Hydrogen Lines 360 15.3 Electron Temperatures and Densities in Emission Regions 366 15.4 Determination of Abundances 371 15.5 Abundances in Emission Regions 374 15.6 Atlas of Simulated Emission Spectra 384 15.7 Problems 385 16 Abundances of the Elements in Galaxies 387 16.1 An Introduction to Galactic and Extragalactic Research 387 16.2 Basic Data for the Chemical Evolution of the Solar Neighborhood 393 16.3 Analytical Models of Chemical Evolution: Basic Relations 395 16.4 Stars and the Total Mass 398 16.5 The Distribution of Stellar Abundances: Infall 400 16.6 Fixing the Model Parameters from Observations 403 16.7 The Distribution of Stellar Abundances: Gas Loss 407 16.8 Recent Developments in Galactic Chemical Evolution 408 16.9 Abundances in Distant Objects 412 16.10 Dark Matter in the Universe 414 16.11 Problems 416 Appendix 418 References 434 Index 462