Physics of the Invisible Sun: Instrumentation, Observations, and Inferences

Cover
Half Title
Frontinspiece
Title Page
Copyright Page
Dedication
Contents
Preface
Author
1. Introduction
1.1 Ancient observations of the Sun
1.2 Pre-telescopic observations of eclipses and sunspots
1.3 Geocentric and heliocentric universe
1.4 The invention of the telescope and discovery of sunspots
1.4.1 Observations of planetary transits from India
1.5 Some early solar observatories
1.6 Major discoveries post-Galileo: from the 17th to the early 20th century
1.6.1 The vanishing act of sunspots during 1645-1715
1.6.2 Discovery of invisible radiations from the Sun
1.6.3 Solar spectral lines: the birth of spectroscopy
1.6.4 Photographic observations of the Sun
1.6.5 Solar differential rotation
1.6.6 Discovery of solar flares
1.6.7 Discovery of helium and the forbidden lines
1.6.8 Magnetic field of sunspots - the Zeeman effect
1.6.9 The Evershed flow around sunspots
1.7 Determination of the Sun’s general properties
1.7.1 Distance and diameter of the Sun
1.7.2 Mass and mean density of the Sun
1.7.3 Effective temperature, luminosity, and the solar constant
1.7.4 The age of the Sun
1.7.5 The elemental abundances
1.8 The extended solar system
1.9 Birth and evolution of the Sun
1.10 The Sun as a star in the Milky Way
1.11 Summary
2. Observing the Visible Sun
2.1 Introduction
2.2 Ground-based solar optical observations
2.2.1 Diffraction-limited spatial resolution of a telescope
2.2.2 Atmospheric ‘seeing’
2.3 Site survey and selection
2.3.1 Building and dome designs
2.4 Solar optical telescopes
2.4.1 Telescope mounts
2.4.2 Heliostats, coelostats, and siderostats
2.4.3 Active and adaptive optics
2.4.4 Off-line image restoration
2.4.5 Some notable solar sites and observing strategies
2.4.6 Advantages of ground-based telescopes
2.5 Solar observations: the analysis techniques
2.5.1 Interference filters: Fabry-Pérot (FP) etalon monochromators
2.5.2 Lyot filter based monochromators
2.5.3 Magneto-optical filters
2.5.4 Michelson interferometers
2.6 Solar spectrographs
2.6.1 Spectroheliograph
2.6.2 Slit-less spectrograph
2.6.3 Echelle spectrograph
2.7 Ground-based coronagraphs: artificial solar eclipses
2.8 Summary
3. The Solar Atmosphere
3.1 Introduction
3.2 The radiative transfer equation
3.2.1 Formation of absorption and emission lines
3.2.2 The thermodynamic equilibrium (TE)
3.3 Optical observations of the photosphere
3.3.1 Limb darkening
3.3.2 The granules
3.3.3 Mesogranules and supergranules
3.3.4 Pores and sunspots
3.3.5 The Evershed flow in sunspots
3.3.6 The solar coordinate system
3.3.7 Solar differential rotation
3.4 Optical observations of the solar chromosphere
3.4.1 Chromospheric features
3.4.2 Solar filaments
3.4.3 Possible mechanisms for heating of the chromosphere
3.5 Optical observations of the white light corona
3.5.1 The various components of the solar corona
3.5.2 Discovery of million-degree temperature of the corona
3.5.3 The coronal heating problem
3.5.4 Possible mechanisms of coronal heating
3.6 Optical observations of solar energetic transients
3.7 Solar flares
3.7.1 Source of flare energy
3.7.2 Conditions for flare onset
3.8 Stability of prominences/filaments
3.8.1 Eruption of filaments/prominences
3.9 Coronal mass ejections (CMEs)
3.9.1 Structure of CMEs
3.9.2 CME mechanism
3.10 Summary
4. Solar Magnetic Field and Activity Cycles
4.1 Solar magnetism
4.2 Magnetic fields in the solar photosphere
4.3 Polarization of radiation and magnetism
4.3.1 The Zeeman polarimetry
4.3.2 Solar magnetic field using Zeeman polarimetry
4.3.3 Degradations of polarimetric measurements
4.3.4 The observational technique
4.3.5 Emergence of solar flux tubes
4.3.6 Nomenclature of active regions
4.3.7 Classification of sunspots/ARs
4.4 Measuring the weak magnetic fields: the Hanle effect
4.5 Solar Dopplergraph/Magnetograph instruments
4.5.1 The GONG Doppler instrument
4.5.2 The Helioseismic and Magnetic Imager (HMI)
4.6 Chromospheric and coronal magnetic fields
4.7 The solar activity cycle
4.7.1 The indices of solar activity
4.7.2 The 11-year sunspot cycles
4.7.3 The long period solar activities
4.7.4 The butterfly diagram of sunspots
4.7.5 The Waldmeier effect
4.7.6 Joy’s law of active region tilts
4.8 Solar magnetic cycles
4.8.1 Hale’s polarity law of sunspot groups
4.8.2 The magnetic butterfly diagram
4.9 Total solar irradiance variation
4.10 Solar dynamo models
4.11 Prediction of solar cycles
4.12 Summary
5. The Invisible Solar Interior: Neutrinos as the Probe
5.1 Introduction
5.2 Modelling the Sun
5.2.1 Standard solar model (SSM)
5.2.2 Basic equations of solar structure
5.2.3 Procedure for calculating a solar model
5.3 Energy production in the central core of the Sun
5.4 Energy transport through the solar interior
5.4.1 The radiative zone
5.4.2 The convective zone
5.4.3 Onset of convection: the Schwarzschild criterion
5.4.4 Mixing length and convective overshoot
5.5 Are the standard solar models reliable?
5.6 Solar neutrinos: messengers from the central core of the Sun
5.6.1 Neutrino detectors: the Homestake experiment
5.6.2 Neutrino detectors: Kamiokande experiment
5.6.3 Neutrino detectors: GALEX, SAGE and GNO
5.6.4 Non-Standard solar models
5.6.5 The Sudbury Neutrino Observatory (SNO)
5.7 Resolution of the solar neutrino problem
5.8 Summary
6. Probing the Invisible Solar Interior: Helioseismology
6.1 Introduction
6.2 Solar oscillations - Helioseismology
6.2.1 Standing waves in acoustic cavities: organ pipes
6.2.2 The Sun as a giant organ pipe
6.3 Physics of trapped solar global modes
6.3.1 Characterisation of oscillation modes
6.3.2 Solar (stellar) oscillations: the basic formalism
6.3.3 Local treatment and the Cowling approximation
6.3.4 Types of solar oscillations: the p- and g-modes
6.3.5 Trapping regions of the modes
6.3.6 The radial structures of the modes
6.3.7 Solar dispersion relation: the l-ν diagram
6.3.8 Observational requirements: frequency resolution
6.3.9 Observational requirements: temporal and spatial resolutions
6.4 Helioseismic observations from ground and space
6.5 Direct and inversion techniques
6.6 Results from inversion techniques
6.6.1 The sound speed and density
6.6.2 Solar radius and the depth of convection zone
6.6.3 Temperature of the central core
6.6.4 Solar internal rotation
6.6.5 The interface, shear layer or “tachocline”
6.6.6 Solar internal magnetic fields
6.6.7 The changes related to solar cycles
6.6.8 Some results of g-mode detection
6.6.9 Limitations of global helioseismology
6.7 Local helioseismology
6.7.1 The ring-diagram techniques
6.7.2 Time-distance analysis
6.7.3 Helioseismic holography: the far-side imaging
6.7.4 The solar transient related changes
6.8 Extension to stars: asteroseismology
6.9 Summary
7. The Invisible Sun in Long Wavelengths
7.1 Introduction
7.2 Detection of IR radiation
7.2.1 IR detectors
7.2.2 Advantages and disadvantages of observing in IR
7.3 IR emissions from the Sun
7.3.1 Imaging and polarimetry of solar atmosphere in IR
7.3.2 Solar flares in IR
7.4 Detection and imaging in radio wavelengths
7.4.1 Radio telescopes
7.4.2 Filled aperture radio telescopes
7.4.3 Unfilled aperture radio telescopes
7.5 Radio emission from the Sun
7.5.1 The black-body, or thermal, solar radio emission
7.5.2 The non-thermal component of solar radio emission
7.5.3 Microwave emissions
7.5.4 Solar radio bursts
7.5.5 Radio diagnostics of coronal magnetic fields
7.5.6 Some solar radio telescopes and radio heliographs
7.5.7 Solar transient in the interplanetary medium
7.6 Solar coronal oscillations – coronal seismology
7.7 Solar MHD formulation: a brief introduction
7.7.1 Maxwell’s equations
7.7.2 MHD approximations
7.7.3 The hydrodynamic equations
7.7.4 The generalised Ohm’s law
7.7.5 MHD instabilities
7.7.6 Magnetic field lines and flux tubes
7.8 Summary
8. The Invisible Sun in Short Wavelengths
8.1 Introduction
8.2 The early era of observing from space
8.3 UV and EUV detection and imaging
8.4 X-ray detection and imaging
8.4.1 X-ray detectors
8.4.2 X-ray imaging
8.4.3 Focussing X-ray mirrors versus collimation
8.5 The γ-ray detection and imaging
8.6 High-energy emissions from the Sun
8.6.1 The transition region
8.6.2 Solar corona in X-rays
8.7 Multi-wavelength observations of solar flares
8.7.1 Coronal signatures of flares in X-rays
8.7.2 High-energy γ-ray emission during transient events
8.7.3 RHESSI and FermiGRO missions
8.7.4 Flare classifications
8.7.5 Modelling the flares
8.7.6 Impact of solar flares and CMEs on space weather
8.7.7 Forecasting of solar flares and CMEs
8.8 The coronal heating problem: observational evidence
8.9 Some past solar space missions
8.9.1 Yohkoh (Solar-A) mission
8.9.2 Hinode (Solar-B) mission
8.9.3 GOES satellites
8.9.4 SOHO satellite
8.9.5 Transition Region and Coronal Explorer (TRACE)
8.9.6 STEREO mission
8.9.7 The RHESSI mission
8.9.8 The Ulysses mission
8.9.9 Coronas-Photon mission
8.10 Recent solar space-missions
8.10.1 Solar Dynamics Observatory (SDO)
8.10.2 Interface Region Imaging Spectrograph (IRIS)
8.10.3 Deep Space Climate Observatory (DSCOVR)
8.10.4 Parker Solar Probe
8.10.5 Aditya-L1 mission
8.11 Summary
9. Solar Wind, Space Weather, and the Heliosphere
9.1 Introduction
9.2 Solar wind: a historical perspective
9.2.1 Chapman’s model of static corona
9.2.2 Parker’s dynamic model of expanding corona
9.2.3 Heliospheric magnetic field: the Parker spiral
9.2.4 Heliospheric magnetic field and solar cycle
9.3 Some properties of solar wind
9.3.1 Fast and slow solar wind
9.3.2 Acceleration of solar wind particles
9.4 The interplanetary medium: quiet and disturbed
9.4.1 Monitoring the I.P.M. from space
9.5 Solar wind interaction with planetary magnetospheres and atmospheres
9.5.1 Encounter with non-magnetic planets/satellites
9.5.2 Encounter with magnetized planets
9.5.3 Drivers of space weather
9.5.4 Detection of solar flares by ionospheric effects
9.6 The heliosphere
9.7 Summary
10. Ongoing and Future Directions
10.1 Ground-based and space-borne solar observatories
10.2 Ongoing, and proposed ground-based optical and IR projects
10.2.1 Daniel K. Inouye Solar Telescope (DKIST)
10.2.2 CrYogenic InfRAred Spectrograph (NST-CYRA)
10.2.3 GREGOR Infrared Spectrograph (GRIS)
10.2.4 European Solar Telescope (EST)
10.2.5 Chinese Large Solar Telescope (CLST)
10.2.6 National Large Solar Telescope (NLST)
10.2.7 Solar Physics Research Integrated Network Group (SPRING)
10.3 Future prospects for solar IR observations
10.3.1 Ground-based solar IR instrumentation
10.3.2 Space-based solar IR instrumentation
10.4 Future prospects for radio solar observations
10.5 Some recent and future space-borne missions
10.6 Solar physics from vantage positions in space
10.6.1 Lagrangian points
10.6.2 NASA-Parker Probe
10.6.3 Solar Orbiter (SolO)
10.6.4 Aditya - L1
10.6.5 Observing from non-SEL Lagrangian points
10.6.6 Observing over the solar polar regions
10.6.7 Space-based observations in radio wavelengths?
10.7 Summary
Bibliography
Index