An Introduction to Stellar Astrophysics

An Introduction to Stellar Astrophysics......Page 5
Contents......Page 9
Preface......Page 13
Acknowledgments......Page 15
1.1 Introduction......Page 17
1.2 The Electromagnetic Spectrum......Page 19
1.3 Blackbody Radiation......Page 21
1.4 Luminosity, Effective Temperature, Flux and Magnitudes......Page 24
1.5 Boltzmann and Saha Equations......Page 29
1.6 Spectral Classification of Stars......Page 37
1.7 The Hertzsprung–Russell Diagram......Page 43
1.8 Summary......Page 46
1.9 Exercises......Page 47
2.1 Introduction......Page 51
2.2 Hydrostatic Equilibrium......Page 52
2.3 The Virial Theorem......Page 56
2.4 The Jeans Criterion......Page 62
2.5 Free-Fall Times......Page 68
2.6 Pre-Main-Sequence Evolution......Page 70
2.8 Exercises......Page 73
3.1 Introduction......Page 77
3.2.1 Matter–Radiation Interactions......Page 78
3.2.2 Types of Radiative Opacities......Page 80
3.3 Specific Intensity and Radiative Moments......Page 85
3.4 Radiative Transfer Equation......Page 93
3.5 Local Thermodynamic Equilibrium......Page 97
3.6 Solution of the Radiative-Transfer Equation......Page 98
3.7 Radiative Equilibrium......Page 106
3.8 Radiative Transfer at Large Optical Depths......Page 107
3.9 Rosseland and Other Mean Opacities......Page 110
3.10 Schwarzschild–Milne Equations......Page 113
3.11 Demonstration of the Radiative-Transfer Equation......Page 115
3.12.1 Radiative Acceleration of Matter......Page 116
3.12.2 Radiative Pressure......Page 119
3.13 Summary......Page 120
3.14 Exercises......Page 121
4.1 Introduction......Page 125
4.2 The Grey Atmosphere......Page 126
4.2.1 The Temperature Profile in a Grey Atmosphere......Page 127
4.2.2 Radiative Flux in a Grey Atmosphere......Page 133
4.3 Line Opacities and Broadening......Page 135
4.3.1 Natural Broadening......Page 136
4.3.2 Doppler Broadening......Page 138
4.3.3 Pressure Broadening......Page 146
4.3.4 Stimulated Emission and Masers......Page 148
4.3.5 Einstein Coefficients......Page 150
4.4.1 Equivalent Width......Page 153
4.4.2 Formation of Weak Atomic Lines......Page 155
4.4.3 Curve of Growth......Page 158
4.5.1 Input Data and Approximations......Page 159
4.5.2 Algorithm for Atmospheric Modelling......Page 161
4.5.3 Example of a Stellar Atmosphere Model......Page 164
4.5.4 Temperature-Correction Procedure......Page 166
4.6 Summary......Page 167
4.7 Exercises......Page 168
5.1 Introduction......Page 171
5.2.2 Equation of Mass Conservation......Page 172
5.2.3 Energy-Transport Equation......Page 175
5.2.4 Equation of Energy Conservation......Page 176
5.2.5 Other Ingredients Needed......Page 177
5.3 Energy Transport in Stars......Page 179
5.3.1 Monochromatic Radiative Flux in Stellar Interiors......Page 180
5.3.2 Conduction......Page 182
5.3.3.1 General Description of Convection......Page 183
5.3.3.2 The Schwarzschild Criterion for Convection......Page 184
5.3.3.3 The Mixing-Length Theory......Page 188
5.4 Polytropic Models......Page 192
5.5 Structure of the Sun......Page 198
5.6.1 Introduction......Page 200
5.6.2 The Ideal Gas......Page 201
5.6.3 Degeneracy......Page 205
5.7.1 Variable Stars......Page 207
5.7.2 Asteroseismology......Page 213
5.7.3 Basic Physics Behind Period–Luminosity Relations......Page 216
5.8 Summary......Page 218
5.9 Exercises......Page 219
6.1 Introduction......Page 221
6.2 Generalities Concerning Nuclear Fusion......Page 222
6.3.1 The Liquid-Drop Model......Page 227
6.3.2 The Shell Model......Page 230
6.4 Basic Physics of Nuclear Fusion......Page 232
6.5 Main-Sequence Burning......Page 234
6.5.1 Proton–Proton Chains......Page 236
6.5.2 CNO Cycles......Page 237
6.5.3 Lifetime of Stars on the Main Sequence......Page 240
6.5.4 The Solar Neutrino Problem......Page 242
6.6 Helium-Burning Phase......Page 246
6.7 Advanced Nuclear Burning......Page 248
6.7.1 Carbon-Burning Phase......Page 249
6.7.3 Oxygen-Burning Phase......Page 250
6.7.4 Silicon-Burning Phase......Page 251
6.8.1 Generalities......Page 252
6.8.2 Evolution of Low-Mass Stars [omitted]......Page 256
6.8.3 Evolution of a [omitted] Star: Our Sun......Page 257
6.8.4 Evolution of Massive Stars [omitted]......Page 261
6.9.1 Stellar Populations, Galaxies and the Milky Way......Page 264
6.9.2 Open Clusters......Page 267
6.9.3 Globular Clusters......Page 268
6.9.4 Age of Stellar Clusters......Page 269
6.9.5 Distance to Stars and Stellar Clusters......Page 271
6.10.1 White Dwarfs......Page 273
6.10.2 Neutron Stars, Pulsars and Magnetars......Page 275
6.10.3 Black Holes......Page 278
6.11 Novae and Supernovae......Page 284
6.12.1 The Slow and Rapid Processes......Page 289
6.12.2 The p Process......Page 292
6.13 Nuclear Reaction Cross Sections and Rates......Page 293
6.15 Exercises......Page 297
7.1 Introduction and Historical Background......Page 301
7.2 Chemically Peculiar Stars......Page 303
7.2.2 Ap Stars......Page 304
7.2.4 He-Abnormal Stars......Page 305
7.3 Atomic Diffusion Theory......Page 306
7.4 Radiative Accelerations......Page 313
7.5 Other Transport Mechanisms......Page 318
7.5.1 Light-Induced Drift......Page 319
7.5.2 Ambipolar Diffusion of Hydrogen......Page 320
7.7 Exercises......Page 321
Answers to Selected Exercises......Page 323
Appendix A: Physical Constants......Page 325
Appendix B: Units in the cgs and SI Systems......Page 327
Appendix C: Astronomical Constants......Page 329
Appendix D: Ionisation Energies (in eV) for the First Five Stages of Ionisation for the Most Important Elements......Page 331
Appendix E: Solar Abundances for the Most Important Elements......Page 333
Appendix F: Atomic Masses......Page 335
Appendix G: Physical Parameters for Main-Sequence Stars......Page 337
Appendix H: Periodic Table of the Elements......Page 339
References......Page 341
Bibliography......Page 343
Index......Page 345
Color plates......Page 355