Magnetic Coupling between the Interior and Atmosphere of the Sun (eBook)

Preface 5
Contents 7
Part I Preamble 24
Republication of: Radial Movement in Sunspots 25
Opening Remarks 33
Solar Physics at the Kodaikanal Observatory: A Historical Perspective 35
1 Background 35
2 Birth of the Kodaikanal Observatory 38
3 John Evershed (1864–1956) 40
3.1 Evershed in Kodaikanal 43
3.2 Evershed Effect 45
3.3 Spectral Lines and Diagnostics 46
3.4 Prominences 47
4 Scientific Impact of the Evershed Effect 48
5 Kodaikanal Observatory: 1923–1960 51
5.1 Eclipse Expeditions 51
5.2 The Saha Committee 51
5.3 Ionospheric and Geomagnetic Laboratory 51
5.4 Solar Instrumentation 52
5.5 Scientific Highlights 53
6 Solar Physics Research at Kodaikanal from 1960 Onwards 54
6.1 Velocity Fields in the Solar Atmosphere 55
6.2 Magnetic Fields 56
6.3 Chromospheric Features and Dynamics 56
6.4 Coronal Studies 57
6.5 Solar Terrestrial Studies 57
6.6 Current Observational Facilities and Programmes 57
7 Future Programmes 58
7.1 National Large Solar Telescope 58
7.2 Space Coronagraph 58
References 59
Vainu Bappu Memorial Lecture: What is a Sunspot? 60
1 Introduction 60
2 Subsequent Milestones of Discovery 62
3 Superficial Sunspot Structure 64
4 The Sunspot Cycle 65
5 What Causes Sunspot Darkening? 70
6 The Rotation of the Sun 76
7 The Overall Structure of a Large Sunspot 80
8 On the Birth, Death, and Lifespan of Sunspots 84
9 Solar-Cycle Irradiance Variation 87
Part II Oral Presentations 90
Angular-Momentum Coupling Through the Tachocline 91
1 Introduction 91
2 Some Initial Remarks on Tachocline Dynamics 93
3 The Early History of Dynamical Tachocline Models 96
4 Some Consequences of Tachocline Circulation 99
5 The Quest for a Tachocline Simulation 102
6 Closing Remarks 105
References 107
Outstanding Issues in Solar Dynamo Theory 109
1 Introduction 109
2 Basic Concepts 111
3 Current State of Our Understanding 112
4 Outstanding Issues 113
4.1 Nature of the Dynamo -Effect 113
4.2 Treatment of Magnetic Buoyancy 114
4.3 Origin of Grand Minima 115
4.4 Parametrization of Turbulent Diffusivity 115
4.5 Role of Downward Flux Pumping 116
5 Concluding Remarks 116
5.1 A Story of Communication Timescales 116
5.2 Solar Cycle Predictions 117
References 118
Status of 3D MHD Models of Solar Global Internal Dynamics 119
1 Introduction: Solar Global MHD 119
2 Global Convection 119
3 Differential Rotation and Meridional Circulation 120
4 Global Dynamo 120
5 Solar Radiation Zone and Its Coupling to the Convection Zone 121
6 Towards a 3D Integrated Model of the Sun 122
References 123
Measuring the Hidden Aspects of Solar Magnetism 124
1 The Zeeman Effect as a Window to Cosmic Magnetism 124
2 Emergence of the Flux Tube Paradigm 126
3 The Hanle Effect as a Window to the Hidden Fields 129
4 The ``Standard Model'' and Its Shortcomings 132
5 The Second Solar Spectrum and Solar Magnetism 134
6 Scale Spectrum of the Magnetic Structures 136
7 Beyond the Standard Model: Scaling Laws and PDFs for a Fractal-Like Field 137
References 139
Recent Advances in Chromospheric and Coronal PolarizationDiagnostics 141
1 Introduction 141
2 The Physical Origin of the Spectral Line Polarization 142
3 The Zeeman Effect vs. the Hanle Effect 145
4 Diagnostic Tools Based on Spectral Line Polarization 146
4.1 Methods for the Chromosphere and Transition Region 146
4.2 Methods for Chromospheric and Coronal Structures 148
5 The Quiet Chromosphere 152
6 Plasma Structures in the Chromosphere and Corona 154
6.1 Off-Limb Diagnostics of Prominences and Spicules 155
6.2 On-Disk Diagnostics of Filaments 156
6.3 Magnetic Field ``Reconstruction" in Emerging Flux Regions 159
7 How to Map the Magnetic Fields of Coronal Loops? 160
8 Concluding Comments 161
References 162
Probability Density Functions to Represent Magnetic Fields at the Solar Surface 164
1 Introduction 164
2 Scalar PDFs 165
2.1 Asymmetric Voigt PDF 165
2.2 Asymmetric Stretched Exponential PDF 167
3 Angular PDFs 169
4 Vector Magnetic Field Distributions 170
5 Conclusions 170
References 172
Spectropolarimetry with CRISP at the Swedish 1-m Solar Telescope 173
1 Introduction 173
2 The June 2008 Campaign Data and Processing 174
3 Inversions and Results 175
4 Discussion 177
References 178
Spectropolarimetry with the NLST 179
1 Introduction 179
2 Polarimetry Package 181
3 Spectropolarimetry with NLST 182
3.1 Multi-slit SP 183
3.2 Integral Field Unit 185
4 Concept Realization 186
5 Conclusions 187
References 188
Magnetic Coupling in the Quiet Solar Atmosphere 189
1 The Magnetic Field of the Quiet Sun 189
2 Coupling of Convection with Magnetic Fields 192
3 Coupling of Waves with Magnetic Fields 197
4 Coupling of Radiation with Magnetic Fields 202
5 Conclusion 205
References 206
The Evershed Effect with SOT/Hinode 209
1 Introduction 209
2 Elementary Structure of the Evershed Flow 210
3 Discussion 212
References 214
The Evershed Flow and the Brightness of the Penumbra 216
1 Introduction 216
2 The Evershed Flow at High Spatial Resolution 218
3 Heating of the Penumbra by the Evershed Flow 225
4 Convection in Penumbral Filaments 228
5 Conclusions 229
References 230
A Topology for the Penumbral Magnetic Fields 233
1 Introduction 233
2 Constraints on the Penumbral Structure 235
3 Model MISMA for Penumbral Filaments with Dark Core 240
4 Scenario for the Small-Scale Structure of the Penumbra 243
5 Qualitative Comparison with Observations 245
6 Discussion and Tests 248
References 249
Theoretical Models of Sunspot Structure and Dynamics 252
1 Introduction 252
2 Umbral Magnetoconvection 253
3 The Inner and Outer Penumbra 254
4 The Formation and Maintenance of the Penumbra 255
5 The Magnetic Field Configuration in the Penumbra 257
6 Numerical Simulations of a Sunspot 260
7 The Evershed Flow 262
8 Conclusions 263
References 264
Convection and the Origin of Evershed Flows 266
1 Introduction 266
2 Recent Modeling Results 268
2.1 Evershed Results 271
3 Local Penumbra Models 273
4 Conclusions and Concluding Remarks 275
References 277
The Magnetic Field of Solar Spicules 278
1 Introduction 278
2 Observations 279
3 Analysis 280
3.1 Detection of Zeeman-Induced Stokes V 281
3.2 Inversions 282
4 Conclusion 283
References 283
Three-Dimensional Magnetic Reconnection 284
1 Introduction 284
2 Characteristics of 2D and 3D Reconnection 286
3 3D Magnetic Interactions 288
3.1 Potential 3D Interaction 288
3.2 3D Resistive MHD Interaction 290
3.3 Recursive Reconnection and Reconnection Rates 293
4 Energetics 296
5 Conclusions 297
References 298
Signatures of Coronal Heating Mechanisms 300
1 Introduction 300
2 Signatures for Alfvén Wave Heating 301
3 Signatures for Nanoflare Reconnection Heating 302
4 Conclusion 303
References 303
Waves in Polar Coronal Holes 304
1 Introduction 304
2 Observation and Results 306
3 Conclusion 307
References 308
MHD Wave Heating Diagnostics 310
1 The State of the Art 310
References 311
Coronal Mass Ejections from Sunspot and Non-Sunspot Regions 312
1 Introduction 312
2 Summary of CME Properties 313
3 Special Populations of CMEs 316
3.1 Halo CMEs 316
3.2 CMEs Resulting in ICMEs 318
3.3 Shock-Driving CMEs 319
3.4 Comparing the Properties of the Special Populations 320
3.5 Solar Sources of the Special Populations 321
4 Solar Cycle Variation 323
4.1 Solar Sources of the General Population 325
4.2 Implications to the Flare: CME Connection 326
5 Sunspot Number and CME Rate 327
6 Summary and Conclusions 328
References 329
CME Observations from STEREO 331
1 Introduction 331
2 What Have We Learnt from LASCO Observations? 333
3 CME Observations from SECCHI/STEREO Coronagraphs 335
4 Summary and Conclusion 337
References 339
Low-Frequency Radio Observations of Coronal Magnetic Fields 341
1 Introduction 341
2 Observations 342
3 Results and Discussion 344
References 346
Evolution of Near-Sun Solar Wind Turbulence 347
1 Introduction 347
2 Interplanetary Scintillation 348
3 Scintillation Spectrum Near the Sun 349
4 Radial Evolution of Small- and Large-Scale Turbulence 351
5 Discussion and Conclusion 353
References 354
The Solar-Stellar Connection 355
1 Introduction 356
2 Sunspot Cycle and Total Solar Irradiance 357
3 The X-Ray Sun 358
4 The Ca II H & K Sun
5 Which Stars are X-Ray Emitters? 361
6 Universality of Stellar X-Ray Emission 363
7 Connection of X-Ray Emission with Other Stellar Parameters 364
8 Coronal Structure 366
9 Conclusions 368
References 368
Summary and Perspective 369
1 A Double Centenary 369
2 The Solar Interior 370
3 Small-Scale Fields and Polarimetry 371
4 Sunspots 372
5 The Quiet Sun 374
6 Coupling to the Atmosphere and Corona 375
7 Eruptive Phenomena: CMEs and Flares 376
8 The Solar-Stellar Connection 376
9 Epilogue 378
References 378
Part III Poster Presentations 379
Evidence for Return Meridional Flows in the Convection Zone 380
1 Introduction 380
2 Measurements 381
3 Results 381
References 383
Long-Term Variations in Meridional Flows 384
1 Introduction 384
2 Data Analysis and Results 385
3 Discussion 386
References 386
Low-Degree High-Frequency p and g Modes in the Solar Core 387
1 Introduction 387
2 The Effect of Low-Degree High-Frequency p Modes 389
3 The Effect of g Modes in the Inversions 389
4 Conclusion 390
References 390
Interior and Exterior Clues of Solar Activity 391
1 Introduction 391
2 The Dynamics of the Radiative Zone 392
3 The Multichannel GOLF-NG Spectrometer 392
4 Building Secular Solar Dynamical Models 395
References 396
Do Active Regions Modify Oscillation Frequencies? 397
1 Introduction 397
2 Analysis and Results 397
References 400
Deep-Focus Diagnostics of Sunspot Structure 401
1 Introduction 401
2 The Flux Tube and Forward Models 402
3 Common Midpoint Deep-Focusing 403
4 Results and Discussion 405
5 Conclusion 407
References 407
Are Polar Faculae Generated by a Local Dynamo? 409
1 Introduction 409
2 Results 410
References 412
The Hanle Effect as Diagnostic Tool for Turbulent Magnetic Fields 413
1 Introduction 413
2 Transfer Equations 414
3 Results 414
3.1 Dependence on the Correlation Length 414
3.2 Dependence on the Magnetic Field Vector PDF 415
4 Conclusions 416
References 416
Phase III of the USO Solar Vector Magnetograph 418
1 Introduction 418
2 Recent Developments 419
3 Ongoing Developments 419
4 Conclusions 420
References 420
Revisit of the Classic Wilson Effect 421
1 Introduction 421
2 Observations and Measurements 422
3 Results and Conclusion 423
References 424
The Waldmeier Effect in Sunspot Cycles 425
1 Introduction 425
2 Observational Study 426
3 Preliminary Theoretical Results 427
References 427
Flare-Driven Acoustic Modes in the Sun 428
1 Introduction 428
2 Data and Analysis 430
3 Discussion and Conclusions 430
References 432
Dynamics of Active Regions Revealed by Tracking of Doppler Features 433
1 Introduction 433
2 The Data and Method 434
3 Results and Conclusions 434
References 435
The Growth of a Primitive Penumbra 436
1 Introduction 436
2 Observations 437
3 Results and Conclusions 437
References 439
Evershed Flow Velocities During 100 Years 440
1 Introduction 440
2 Data and Results 441
3 Discussion and Conclusion 441
References 442
The Thermal Structure of Sunspots 444
1 Introduction 444
2 Data and Analysis 445
3 Results and Conclusions 445
References 446
Bright Points in G-Band and CaiiH Images from Hinode 447
1 Observations, Analysis, and Results 447
Waves in the Transition Region 449
1 Introduction 449
2 Evidence 449
References 451
Viscous Damping of Alfvén Surface Waves with Steady Flows 452
1 Introduction 452
2 Dispersion Relation 453
3 Discussion and Conclusion 453
References 454
Statistical Detection of Propagating Waves in a Polar Coronal Hole 456
1 Introduction 456
2 Observations and Data Analysis 457
3 Results and Discussion 457
References 459
Network Loop Oscillations with EIS/Hinode 460
1 Introduction 460
2 Observations 460
3 Magnetoacoustic Oscillations 461
References 462
Dynamical Evolution of X-Ray Bright Points with Hinode/XRT 463
1 Introduction 463
2 Results and Discussion 464
References 465
Helicity at Photospheric and Chromospheric Heights 466
1 Introduction 466
2 Sign of Magnetic Helicity 467
3 Data 468
4 Results and Discussion 468
References 470
Evolution of Coronal Helicity in a Twisted Emerging Active Region 471
1 Introduction 471
2 Results 472
3 Discussion 474
References 474
Power-Law Nanoflare Heating 475
1 Introduction 475
2 Power-Law Estimates 475
References 476
Spectroscopic Diagnostics of Polar Coronal Plumes 477
1 Introduction 477
2 Spectroscopic Observations of Coronal Plumes 478
3 Results and Discussion 479
References 481
A Flaring Polar Filament 482
1 Introduction 482
2 Observations 483
References 485
Solar X-Ray Processes 486
References 487
Time-Varying Thermal Emission in Solar Flares 488
1 Introduction 488
2 Observations, Analysis, Results 490
3 Conclusion 492
References 493
Multi-Wavelength View of Flare Events on 20 November 2003 494
1 Flare Events on 20 November 2003 494
2 Reorganization of Magnetic Structures 495
3 Results and Discussion 496
References 497
Time-Delay Between Solar Soft X-Ray and EUV Flare Emissions 498
1 Introduction 498
2 Results and Discussion 499
References 500
Major Surge Activity of Super-Active Region NOAA 10484 501
1 Introduction 501
2 Observations 502
3 Results and Discussion 504
References 504
Coronal Magnetic Field Estimation Using Type-II Radio Bursts 505
1 Observations, Analysis, Results 505
References 507
Acceleration of CMEs Associated with Eruptive Prominences 508
1 Introduction 508
2 Observations 508
3 Discussion and Summary 509
4 Future Plan 511
References 511
Interplanetary Consequences of a Large CME 512
1 Introduction: Intense Flare and CME 512
2 Radio Spectra, Particle Fluxes, and Scintillation Images 512
3 Conclusion 516
References 516
Solar System Resonances on Light-Travel Time ScalesSet Up before Proto-Sun's Nuclear Ignition 517
1 Introduction 517
2 Fourier Frequencies in Momentum Transfer 518
3 Resonance Set-Up During the Approach to and Onset of Steady State 519
4 Conclusion 519
References 519
Part IV Summaries of Presentations Published Elsewhere 520
Cycle Prediction from Dynamo Theory 521
References 522
Why Does the Torsional Oscillation Precede the Sunspot Cycle? 523
References 524
The Subsurface Magnetic Structure of Solar Active Regions 525
Sunspot Magnetometry from Kodaikanal 527
References 527
Vector Magnetic Field in Emerging Flux Regions 528
References 529
Evolution of Umbral Dots and Penumbral Grains 530
Strong, Localized Downflows in a Sunspot Light Bridge 532
Small-Scale Velocities in Sunspot Penumbrae 533
Photospheric Temperatures from CaiiH 534
References 535
Dual-Line Spectral Imaging of the Chromosphere 536
Inversions of High-Cadence SOLIS-VSM Stokes Observations 538
References 538
Flows in Flaring and Dormant Active Regions 539
References 539
Magnetic and Velocity Field Changes Related to the Solar Flares of 28 and 29 October 2003 540
References 540
A Numerical Investigation of Unsheared Flux Cancelation 541
Wave Heating of Coronal Loops with Steady Flows 543
References 543
Damping of Prominence Oscillations in Steady Equilibrium 544
Variation of Network Contrast with Height 545
A Flaring Twisted Emerging Flux Region 546
Reference 547
Evidence of Magnetic Reconnection Outflows in a Flare seenby Hinode/EIS 548
Does Coronal Rotation Period Depend on the Sunspot Number? 549
1 Introduction 549
2 Feature Tracking 549
3 Spectral Measurements 550
4 Rotation Measurements from Flux Modulation 550
5 Data Analysis and Results 550
References 551
Coronal Magnetic Field from an Extreme Radio Burst 552
CME Kinematics and Dynamics 553
References 553
Solar Wind Monitoring with SWIM-SARA Onboard Chandrayaan-1 554
Coupling of the Solar Wind and the Magnetosphere 556
The FIP Effect in RV Tauri Stars 558
Author Index 559