Exoplanet Atmospheres

Sara Seager is professor of planetary science and physics at the Massachusetts Institute of Technology.

"Seager provides an excellent contribution to the Princeton Series in Astrophysics, which will appeal to graduate students and working professionals in astronomy."--Choice "The author, an acknowledged leader in the field, has written a text intended for advanced undergraduates, graduate students, and professional astronomers. The book is organized topically, and could easily be used alone or as part of a more general course in thermodynamics or radiation astrophysics... This is an excellent resource... The author's clear explanations are easy to follow."--April S. Whitt, Planetarian "As a basic textbook for an introductory course in atmospheric physics for undergraduates this book is fine; it's nicely and clearly written and includes model exam questions."--F. W. Taylor, Observatory "The book will certainly provide a useful starting point for what I suspect will be the increasing number of scientists wishing to work on the physics of exoplanets."--Jonathan Tennyson, Contemporary Physics

• Preface xi Chapter 1: Introduction 1 1.1 Exoplanets from Afar 1 1.2 Two Paths to Observing Exoplanet Atmospheres 2 1.3 Types of Planets 4 Chapter 2: Intensity and Flux 9 2.1 Introduction 9 2.2 Intensity 9 2.3 Flux and Other Intensity Moments 10 2.4 Surface Flux 11 2.5 Observed Flux 14 2.6 Luminosity and Outgoing Energy 16 2.7 Incident Flux and Incident Energy 17 2.8 Black Body Intensity and Black Body Flux 19 2.9 Lambert Surface 20 2.10 Summary 22 Chapter 3: Temperature, Albedos, and Flux Ratios 25 3.1 Introduction 25 3.2 Energy Balance 25 3.3 Planetary Temperatures 27 3.4 Planetary Albedos 32 3.5 Planet-Star Flux Ratios 40 3.6 Planetary Phase Curves 45 3.7 Summary 47 Chapter 4: Composition of a Planetary Atmosphere 51 4.1 Introduction 51 4.2 Composition of Earth's and Jupiter's Atmospheres 51 4.3 Chemical Composition 56 4.4 Basic Cloud Physics 66 4.5 Atmospheric Escape 72 4.6 Atmospheric Evolution 81 4.7 Summary 83 Chapter 5: Radiative Transfer I: Fundamentals 87 5.1 Introduction 87 5.2 Opacity 87 5.3 Optical Depth 91 5.4 Local Thermodynamic Equilibrium 93 5.5 The Source Function 96 5.6 The Equation of Radiative Transfer 96 5.7 Summary 100 Chapter 6: Radiative Transfer II: Solutions 103 6.1 Introduction 103 6.2 A Conceptual Description of the Emergent Spectrum 103 6.3 An Introduction to Line Formation 108 6.4 Approximate Solutions to the Plane-Parallel Radiative Transfer Equation 113 6.5 Monte Carlo Radiative Transfer 125 6.6 Summary 127 Chapter 7: Polarization 133 7.1 Introduction 133 7.2 Description of Polarized Radiation 134 7.3 Polarization Calculations 138 7.4 Polarization from Planets 140 7.5 Summary 143 Chapter 8: Opacities 145 8.1 Introduction 145 8.2 Energy Levels in Atoms and Molecules 146 8.3 Molecular Absorption Cross Sections 161 8.4 Rayleigh Scattering 166 8.5 Condensate Opacities 167 8.6 Summary 176 Chapter 9: Vertical Thermal Structure of a Planetary Atmosphere 181 9.1 Introduction 181 9.2 Earth's Vertical Atmospheric Structure 181 9.3 Hydrostatic Equilibrium and the Pressure Scale Height 183 9.4 Surface Temperature for a Simplified Atmosphere 186 9.5 Convection versus Radiation 190 9.6 The Radiative Equilibrium Temperature Profile 192 9.7 The Adiabatic Temperature Profile 200 9.8 The One-Dimensional Temperature-Pressure Profile 202 9.9 Temperature Retrieval 205 9.10 Summary 207 10.Atmospheric Circulation 211 10.1 Introduction 211 10.2 Radiative and Advective Timescales 213 10.3 Large-Scale Flow and Patterns 215 10.4 Atmospheric Dynamics Equations 218 10.5 Connection to Observations 223 10.6 Summary 225 11.Atmospheric Biosignatures 229 11.1 Introduction 229 11.2 Earth's Biosignatures 229 11.3 The Ideal Biosignature Gas 230 11.4 Prospects 231 11.5 Summary 234 A. Planetary Data 237 Index 241