Cover -- Half-title -- Series-title -- Title -- Copyright -- Dedication -- Contents -- Preface -- 1 The Sun among the stars -- 1.1 Sunspots and solar magnetic activity -- 1.2 The Sun as a star -- 1.2.1 Solar structure -- 1.2.2 Properties and classification of stars -- 1.3 Starspots and stellar magnetic activity -- 1.3.1 The solar-stellar connection -- 1.3.2 Spots on stars -- 1.4 Plan of the book -- 1.5 References for background reading -- 2 Sunspots and starspots: a historical introduction -- 2.1 Early observations of sunspots -- 2.2 The sunspot cycle -- 2.2.1 The Maunder Minimum -- 2.2.2 Photographic studies of sunspots -- 2.3 Fine structure in sunspots -- 2.4 Spectroscopy and the sunspot magnetic field -- 2.4.1 Hale's discovery of the sunspot magnetic field -- 2.4.2 The Evershed effect -- 2.5 Solar granulation and supergranulation -- 2.6 Theoretical advances -- 2.6.1 The development of magnetohydrodynamics -- 2.6.2 Magnetoconvection -- 2.6.3 Dynamo theory -- 2.6.4 The solar wind -- 2.7 Recent progress on sunspots -- 2.8 Starspots -- 2.9 Chronology of key developments (1610-1964) -- 3 Overall structure of a sunspot -- 3.1 Morphology of sunspots -- 3.2 Thermal properties of sunspots -- 3.2.1 The cooling of sunspots -- 3.2.2 Brightness of the umbra and penumbra -- 3.2.3 The weak bright ring around a sunspot -- Observations of the bright ring -- Thermal models of sunspots -- 3.2.4 The Wilson depression -- 3.3 Spectroscopy and atmospheric models -- 3.3.1 Spectral analysis of the umbra and penumbra -- 3.3.2 Semi-empirical models of umbral and penumbral atmospheres -- Umbral models -- Penumbral models -- 3.3.3 The chromospheric superpenumbra -- 3.3.4 The transition region and corona above a sunspot -- 3.4 Observations of the magnetic field in sunspots -- 3.4.1 The Zeeman effect -- 3.4.2 The magnetic field in a pore -- 3.4.3 Magnetic fields in sunspots.

3.5 Modelling the overall magnetic structure of a sunspot -- 3.5.1 Static axisymmetric models -- Potential-field models -- Self-similar models -- The role of the penumbra -- 3.5.2 Stability of static models -- 3.6 The moat flow -- 4 Fine structure of the umbra -- 4.1 Umbral dots -- 4.2 Convection in the umbra -- 4.2.1 Idealized model calculations -- 4.2.2 Realistic simulations -- 4.2.3 Magnetic structure of the umbra -- 4.3 Light bridges -- 5 Fine structure of the penumbra -- 5.1 Penumbral filaments -- 5.1.1 Bright grains in penumbral filaments -- 5.1.2 Dark cores within bright filaments -- 5.2 The intricate structure of the penumbral magnetic field -- 5.2.1 The interlocking-comb magnetic structure -- 5.2.2 Velocity structure -- 5.2.3 Hyperfine structure and dark cores -- 5.3 Convection in the penumbra -- 5.3.1 Travelling patterns in inclined magnetic fields -- 5.3.2 Convection in the inner penumbra -- 5.3.3 Buoyancy braking and the origin of dark cores -- 5.3.4 Dark filaments and convection in the outer penumbra -- 5.3.5 Thin flux tubes in the penumbra -- 5.4 The Evershed flow -- 5.4.1 Fine-scale organization of the Evershed flow -- 5.4.2 Theoretical models of the Evershed flow -- 5.5 Moving magnetic features in the moat -- 5.6 Formation and maintenance of the penumbra -- 5.6.1 Magnetic flux pumping and returning flux tubes -- Idealized model calculations -- Flux pumping at the solar photosphere -- 5.6.2 Formation of the penumbra -- 6 Oscillations in sunspots -- 6.1 Magneto-atmospheric waves -- 6.2 Umbral oscillations -- 6.2.1 Five-minute umbral oscillations -- 6.2.2 Three-minute umbral oscillations and umbral flashes -- 6.2.3 Magnetic field variations -- 6.2.4 Theoretical interpretations of umbral oscillations -- 6.3 Penumbral waves -- 6.4 Sunspot seismology -- 6.4.1 Absorption of p-modes by a sunspot.

6.4.2 Time--distance and holographic seismology of sunspots -- 6.4.3 Acoustic halos -- 7 Sunspots and active regions -- 7.1 Description of active regions -- 7.1.1 Pores and their relation to sunspots -- 7.1.2 Faculae and plages -- 7.2 Birth and evolution of active regions -- 7.2.1 Magnetic flux emergence in active regions -- 7.2.2 Theoretical models of emerging magnetic flux -- Thin flux tubes rising through the convection zone -- Numerical simulations of flux emergence -- 7.2.3 Intense magnetic elements -- Convective collapse of a thin flux tube -- Formation of intense flux elements in nonlinear magnetoconvection -- 7.3 Formation, growth and decay of sunspots -- 7.3.1 Growth rates of sunspots -- 7.3.2 Lifetimes of sunspots -- 7.3.3 The decay of a sunspot -- Decay laws for sunspot area and magnetic flux -- Diffusion models of sunspot decay -- 7.4 Sunspot groups -- 7.4.1 The magnetic configuration of active regions and sunspot groups -- 7.4.2 Sunspots and solar rotation -- 7.5 Dissolution of active regions -- 7.6 Flux emergence in the quiet Sun -- 7.6.1 Ephemeral active regions -- 7.6.2 Intergranular magnetic fields and smaller-scale flux emergence -- 8 Magnetic activity in stars -- 8.1 Stellar Ca II emission -- 8.2 Variation of activity with rotation rate and age -- 8.3 Vigorous activity in late-type stars -- 8.4 Other magnetic stars -- 9 Starspots -- 9.1 Observing techniques -- 9.1.1 Photometry -- 9.1.2 Spectroscopy -- Line-depth ratios -- Molecular lines -- 9.1.3 Doppler imaging -- Technique -- 9.1.4 Zeeman-Doppler imaging -- 9.2 Case studies of starspots -- 9.2.1 EK Draconis and other solar analogues -- 9.2.2 RS CVn binaries and FK Com stars -- 9.2.3 BY Draconis -- 9.2.4 AB Doradus -- 9.2.5 T Tauri stars -- 9.3 Starspots, differential rotation and dynamo patterns -- 9.3.1 Differential rotation -- 9.3.2 Starspots and surface patterns of activity.

The latitude distribution of starspots -- Active longitudes -- 9.3.3 Starspot cycles from long-term photometry -- 9.4 Properties of individual starspots -- 9.4.1 Temperatures and areas -- 9.4.2 Magnetic fields -- 9.4.3 Lifetimes -- 9.4.4 Sunspots as prototypes for starspots? -- 10 Solar and stellar activity cycles -- 10.1 Cyclic activity in the Sun -- 10.2 Modulation of cyclic activity and grand minima -- 10.3 Differential rotation in the Sun -- 10.4 Variable activity in stars -- 10.4.1 Stellar activity cycles -- 10.4.2 Cyclic behaviour in more active stars -- 11 Solar and stellar dynamos -- 11.1 Basic dynamo theory -- 11.1.1 Cowling's theorem -- 11.1.2 Mean-field magnetohydrodynamics and the alpha-effect -- 11.2 Phenomenology of the solar dynamo -- 11.3 The solar dynamo -- 11.3.1 Physical mechanisms -- 11.3.2 Location -- 11.3.3 Models of the solar cycle -- 11.3.4 Modulation and grand minima -- 11.4 Stellar dynamos -- 11.4.1 Slow rotators -- 11.4.2 Rapid rotators and polar spots -- 11.4.3 Fully convective stars -- 11.5 Small-scale dynamo action -- 11.6 Numerical simulation of solar and stellar dynamos -- 12 Solar activity, space weather and climate change -- 12.1 The variable solar irradiance -- 12.1.1 Sunspots, faculae and the solar irradiance -- 12.1.2 Spectral variability -- 12.2 Interplanetary effects of solar activity -- 12.2.1 Solar flares and coronal mass ejections -- 12.2.2 Space weather -- 12.2.3 Variations in the open solar magnetic flux -- 12.3 Solar variability and the Earth's climate -- 12.3.1 Changes in the Earth's orbit -- 12.3.2 Effects of solar variability -- The 11-year activity cycle -- Longer-term climatic change -- Amplification mechanisms -- 12.4 Global warming -- 13 The way ahead -- 13.1 The structure and dynamics of a sunspot -- 13.2 Solar and stellar activity cycles -- 13.3 Starspots -- 13.4 Prospect for the future.

Appendix 1 Observing techniques for sunspots -- A1.1 High-resolution solar telescopes -- A1.2 Correcting for atmospheric seeing and stray light -- A1.3 Imaging and narrow-band filters -- A1.4 Spectroscopy -- A1.5 Polarimetry -- A1.6 Inversion methods -- Appendix 2 Essentials of magnetohydrodynamic theory -- A2.1 Basic equations -- A2.2 Kinematic MHD: flux freezing, flux concentration and flux expulsion -- A2.3 MHD waves -- A2.4 Thin flux tubes -- A2.5 Fundamentals of magnetoconvection -- References -- Index.

A comprehensive account of sunspots and starspots for graduate students, astronomers, geophysicists, space physicists and experts in solar and stellar physics.

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Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, 2018. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries.