The past two decades have seen remarkable advances in observations of sunspots and their magnetic fields, in imaging of spots and fields on distant stars, and in associated theoretical models and numerical simulations.

John H. Thomas, Department of Mechanical Engineering and Department of Physics and Astronomy, University of Rochester, USA Nigel O. Weiss, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, UK

Preface	p. xv
The Sun among the stars	p. 1
Sunspots and solar magnetic activity	p. 1
The Sun as a star	p. 5
Solar structure	p. 5
Properties and classification of stars	p. 7
Starspots and stellar magnetic activity	p. 10
The solar-stellar connection	p. 10
Spots on stars	p. 11
Plan of the book	p. 13
References for background reading	p. 13
Sunspots and starspots: a historical introduction	p. 15
Early observations of sunspots	p. 15
The sunspot cycle	p. 20
The Maunder Minimum	p. 22
Photographic studies of sunspots	p. 22
Fine structure in sunspots	p. 23
Spectroscopy and the sunspot magnetic field	p. 26
Hale's discovery of the sunspot magnetic field	p. 26
The Evershed effect	p. 27
Solar granulation and supergranulation	p. 28
Theoretical advances	p. 29
The development of magnetohydrodynamics	p. 29
Magnetoconvection	p. 30
Dynamo theory	p. 31
The solar wind	p. 31
Recent progress on sunspots	p. 32
Starspots	p. 33
Chronology of key developments (1610-1964)	p. 36
Overall structure of a sunspot	p. 38
Morphology of sunspots	p. 38
Thermal properties of sunspots	p. 41
The cooling of sunspots	p. 41
Brightness of the umbra and penumbra	p. 42
The weak bright ring around a sunspot	p. 45
The Wilson depression	p. 46
Spectroscopy and atmospheric models	p. 47
Spectral analysis of the umbra and penumbra	p. 47
Semi-empirical models of umbral and penumbral atmospheres	p. 48
The chromospheric superpenumbra	p. 50
The transition region and corona above a sunspot	p. 52
Observations of the magnetic field in sunspots	p. 54
The Zeeman effect	p. 54
The magnetic field in a pore	p. 57
Magnetic fields in sunspots	p. 58
Modelling the overall magnetic structure of a sunspot	p. 60
Static axisymmetric models	p. 62
Stability of static models	p. 65
The moat flow	p. 65
Fine structure of the umbra	p. 68
Umbral dots	p. 68
Convection in the umbra	p. 70
Idealized model calculations	p. 71
Realistic simulations	p. 73
Magnetic structure of the umbra	p. 74
Light bridges	p. 75
Fine structure of the penumbra	p. 78
Penumbral filaments	p. 78
Bright grains in penumbral filaments	p. 80
Dark cores within bright filaments	p. 83
The intricate structure of the penumbral magnetic field	p. 83
The interlocking-comb magnetic structure	p. 84
Velocity structure	p. 87
Hyperfine structure and dark cores	p. 88
Convection in the penumbra	p. 89
Travelling patterns in inclined magnetic fields	p. 90
Convection in the inner penumbra	p. 91
Buoyancy braking and the origin of dark cores	p. 92
Dark filaments and convection in the outer penumbra	p. 92
Thin flux tubes in the penumbra	p. 93
The Evershed flow	p. 93
Fine-scale organization of the Evershed flow	p. 94
Theoretical models of the Evershed flow	p. 95
Moving magnetic features in the moat	p. 97
Formation and maintenance of the penumbra	p. 99
Magnetic flux pumping and returning flux tubes	p. 100
Formation of the penumbra	p. 103
Oscillations in sunspots	p. 106
Magneto-atmospheric waves	p. 106
Umbral oscillations	p. 107
Five-minute umbral oscillations	p. 108
Three-minute umbral oscillations and umbral flashes	p. 110
Magnetic field variations	p. 113
Theoretical interpretations of umbral oscillations	p. 114
Penumbral waves	p. 117
Sunspot seismology	p. 118
Absorption of p-modes by a sunspot	p. 118
Time-distance and holographic seismology of sunspots	p. 121
Acoustic halos	p. 122
Sunspots and active regions	p. 123
Description of active regions	p. 123
Pores and their relation to sunspots	p. 123
Faculae and plages	p. 125
Birth and evolution of active regions	p. 128
Magnetic flux emergence in active regions	p. 129
Theoretical models of emerging magnetic flux	p. 131
Intense magnetic elements	p. 133
Formation, growth and decay of sunspots	p. 136
Growth rates of sunspots	p. 136
Lifetimes of sunspots	p. 138
The decay of a sunspot	p. 138
Sunspot groups	p. 141
The magnetic configuration of active regions and sunspot groups	p. 141
Sunspots and solar rotation	p. 142
Dissolution of active regions	p. 143
Flux emergence in the quiet Sun	p. 144
Ephemeral active regions	p. 145
Intergranular magnetic fields and smaller-scale flux emergence	p. 147
Magnetic activity in stars	p. 150
Stellar Ca II emission	p. 150
Variation of activity with rotation rate and age	p. 151
Vigorous activity in late-type stars	p. 155
Other magnetic stars	p. 156
Starspots	p. 158
Observing techniques	p. 158
Photometry	p. 158
Spectroscopy	p. 160
Doppler imaging	p. 162
Zeeman-Doppler imaging	p. 167
Case studies of starspots	p. 168
EK Draconis and other solar analogues	p. 169
RS CVn binaries and FK Com stars	p. 171
BY Draconis	p. 172
AB Doradus	p. 173
T Tauri stars	p. 176
Starspots, differential rotation and dynamo patterns	p. 177
Differential rotation	p. 177
Starspots and surface patterns of activity	p. 179
Starspot cycles from long-term photometry	p. 180
Properties of individual starspots	p. 180
Temperatures and areas	p. 180
Magnetic fields	p. 181
Lifetimes	p. 182
Sunspots as prototypes for starspots?	p. 182
Solar and stellar activity cycles	p. 184
Cyclic activity in the Sun	p. 184
Modulation of cyclic activity and grand minima	p. 185
Differential rotation in the Sun	p. 189
Variable activity in stars	p. 191
Stellar activity cycles	p. 191
Cyclic behaviour in more active stars	p. 193
Solar and stellar dynamos	p. 194
Basic dynamo theory	p. 194
Cowling's theorem	p. 195
Mean-field magnetohydrodynamics and the [alpha]-effect	p. 195
Phenomenology of the solar dynamo	p. 197
The solar dynamo	p. 198
Physical mechanisms	p. 199
Location	p. 200
Models of the solar cycle	p. 201
Modulation and grand minima	p. 204
Stellar dynamos	p. 205
Slow rotators	p. 206
Rapid rotators and polar spots	p. 206
Fully convective stars	p. 207
Small-scale dynamo action	p. 209
Numerical simulation of solar and stellar dynamos	p. 210
Solar activity, space weather and climate change	p. 211
The variable solar irradiance	p. 211
Sunspots, faculae and the solar irradiance	p. 213
Spectral variability	p. 215
Interplanetary effects of solar activity	p. 216
Solar flares and coronal mass ejections	p. 216
Space weather	p. 217
Variations in the open solar magnetic flux	p. 220
Solar variability and the Earth's climate	p. 221
Changes in the Earth's orbit	p. 221
Effects of solar variability	p. 222
Global warming	p. 227
The way ahead	p. 229
The structure and dynamics of a sunspot	p. 229
Solar and stellar activity cycles	p. 230
Starspots	p. 230
Prospect for the future	p. 231
Observing techniques for sunspots	p. 232
Essentials of magnetohydrodynamic theory	p. 238
References	p. 246
Index	p. 271
Table of Contents provided by Ingram. All Rights Reserved.

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