Introduction to Stellar Astrophysics 2nd edition [Minkštas viršelis]

Contents

Preface              xi

Acknowledgments     xiii

Chapter 1: Basic Concepts   1

1.1 Introduction           1

1.2 The Electromagnetic Spectrum 3

1.3 Blackbody Radiation        5

1.4 Luminosity, Effective Temperature, Flux and Magnitudes        8

1.5 Boltzmann and Saha Equations                13

1.6 Spectral Classification of Stars 21

1.7 The HertzsprungRussell Diagram          27

1.8 Nearest and Brightest Stars

1.9 Summary              30

1.10 Exercises            31

Chapter 2: Stellar Formation               35

2.1 Introduction           35

2.2 Hydrostatic Equilibrium 36

2.3 The Virial Theorem             40

2.4 The Jeans Criterion            46

2.5 Free-Fall Times 52

2.6 Pre-Main-Sequence Evolution 54

2.7 Summary 57

2.8 Exercises 57

Chapter 3: Radiative Transfer in Stars            61

3.1 Introduction           61

3.2 Radiative Opacities           62

3.2.1 MatterRadiation Interactions               62

3.2.2 Types of Radiative Opacities   64

3.3 Specific Intensity and Radiative Moments         69

3.4 Radiative Transfer Equation         77

3.5 Local Thermodynamic Equilibrium         81

3.6 Solution of the Radiative-Transfer Equation      82

3.7 Radiative Equilibrium       90

3.8 Radiative Transfer at Large Optical Depths        91

3.9 Rosseland and Other Mean Opacities 94

3.10 SchwarzschildMilne Equations       97

3.11 Demonstration of the Radiative-Transfer Equation 99

3.12 Radiative Acceleration of Matter and Radiative Pressure    100

3.12.1 Radiative Acceleration of Matter       100

3.12.2 Radiative Pressure      103

3.13 Summary              104

3.14 Exercises               105

Chapter 4: Stellar Atmospheres        109

4.1 Introduction           109

4.2 The Grey Atmosphere      110

4.2.1 The Temperature Profile in a Grey Atmosphere           111

4.2.2 Radiative Flux in a Grey Atmosphere            117

4.3 Line Opacities and Broadening 119

4.3.1 Natural Broadening       120

4.3.2 Doppler Broadening     122

4.3.3 Pressure Broadening    130

4.3.4 Stimulated Emission and Masers        132

4.3.5 Einstein Coefficients               134

4.4 Equivalent Width and Formation of Atomic Lines          137

4.4.1 Equivalent Width            137

4.4.2 Formation of Weak Atomic Lines         139

4.4.3 Curve of Growth           142

4.5 Atmospheric Modelling  143

4.5.1 Input Data and Approximations            143

4.5.2 Algorithm for Atmospheric Modelling           145

4.5.3 Example of a Stellar Atmosphere Model         148

4.5.4 Temperature-Correction Procedure              150

4.6 Types of Binary Stars

4.7 Summary              151

4.8 Exercises               152

Chapter 5: Stellar Interiors    155

5.1 Introduction           155

5.2 Equations of Stellar Structure    156

5.2.1 Hydrostatic Equilibrium Equation       156

5.2.2 Equation of Mass Conservation            156

5.2.3 Energy-Transport Equation       159

5.2.4 Equation of Energy Conservation         160

5.2.5 Other Ingredients Needed        161

5.3 Energy Transport in Stars               163

5.3.1 Monochromatic Radiative Flux in Stellar Interiors    164

5.3.2 Conduction        166

5.3.3 Convection         167

5.3.3.1 General Description of Convection                167

5.3.3.2 The Schwarzschild Criterion for Convection          168

5.3.3.3 The Mixing-Length Theory                172

5.3.3.4 Convective Equilibrium       176

5.4 Polytropic Models               176

5.5 Structure of the Sun          182

5.6 Equation of State                184

5.6.1 Introduction       184

5.6.2 The Ideal Gas    185

5.6.3 Degeneracy        189

5.6.4 Radiation Pressure        191

5.7 The Eddington Limit

5.87 Variable Stars and Asteroseismology 191

5.87.1 Variable Stars                 191

5.87.2 Asteroseismology     197

5.87.3 Basic Physics Behind PeriodLuminosity Relations           200

5.9 Summary              202

5.10 Exercises            203

Chapter 6: Nucleosynthesis and Stellar Evolution                205

6.1 Introduction           205

6.2 Generalities Concerning Nuclear Fusion            206

6.3 Models of the Nucleus 211

6.3.1 The Liquid-Drop Model               211

6.3.2 The Shell Model               214

6.4 Basic Physics of Nuclear Fusion               216

6.5 Main-Sequence Burning                 218

6.5.1 ProtonProton Chains                 220

6.5.2 CNO Cycles       221

6.5.3 Lifetime of Stars on the Main Sequence          224

6.5.4 The Solar Neutrino Problem 226

6.6 Helium-Burning Phase    230

6.7 Advanced Nuclear Burning           232

6.7.1 Carbon-Burning Phase               233

6.7.2 Neon-Burning Phase    234

6.7.3 Oxygen-Burning Phase                234

6.7.4 Silicon-Burning Phase                 235

6.8 Evolutionary Tracks in the HR Diagram              236

6.8.1 Generalities       236

6.8.2 Evolution of Low-Mass Stars (M* _ 0.5 M_)            240

6.8.3 Evolution of a 1 M_ Star: Our Sun         241

6.8.4 Evolution of Massive Stars (M* _ 10 M_) 245

6.9 Stellar Evolution Modelling

6.10 Stellar Clusters               248

6.10.1 Stellar Populations, Galaxies and the Milky Way 248

6.10.2 Open Clusters            251

6.10.3 Globular Clusters                     252

6.10.4 Age of Stellar Clusters           253

6.10.5 Distance to Stars and Stellar Clusters        255

6.11 Stellar Remnants 257

6.11.0.1 White Dwarfs 257

6.11.2 Neutron Stars, Pulsars and Magnetars 259

6.11.3 Black Holes 262

6.12 Novae and Supernovae 268

6.13 Heavy Element Nucleosynthesis: s, r and p Processes 273

6.13.1 The Slow and Rapid Processes 273

6.13.2 The p Process 276

6.14 Nuclear Reaction Cross Sections and Rates 277

6.15 Summary 281

6.16 Exercises 281

Chapter 7: Chemically Peculiar Stars and Diffusion 285

7.1 Introduction and Historical Background 285

7.2 Chemically Peculiar Stars 287

7.2.1 Am Stars 288

7.2.2 Ap Stars 288

7.2.3 HgMn Stars 289

7.2.4 He-Abnormal Stars 289

7.3 Atomic Diffusion Theory 290

7.4 Radiative Accelerations 297

7.5 Other Transport Mechanisms 302

7.5.1 Light-Induced Drift 303

7.5.2 Ambipolar Diffusion of Hydrogen 304

7.6 Summary 305

7.7 Exercises 305

Answers to Selected Exercises          307

Appendix A: Physical Constants       309

Appendix B: Units in the cgs and SI Systems            311

Appendix C: Astronomical Constants           313

Appendix D: Ionisation Energies (in eV) for the First Five Stages of
Ionisation for the Most Important Elements          315

Appendix E: Solar Abundances for the Most Important Elements             
317

Appendix F: Atomic Masses 319

Appendix G: Physical Parameters for Main-Sequence Stars           321

Appendix H: Periodic Table of the Elements              323

References      325

Bibliography   327

Index    329

Francis LeBlanc, PhD, is Professor in the Department of Physics and Astronomy of Université de Moncton (Canada). His fields of expertise are diffusion in stars, chemically peculiar stars, and stellar atmospheres. Professor LeBlanc is responsible for the university's observatory and has taught several undergraduate courses on general astronomy, astrophysics and space sciences, and modern physics and nuclear physics, as well as a graduate course on stellar astrophysics.