Solar Polarization


Book Description

Novel instruments for high-precision imaging polarimetry have opened new possibilities, including for exploring effects in radiative scattering, atomic physics, spectral line formation, and radiative transfer. This volume gives a comprehensive and up-to-date account of this rapidly evolving and interdisciplinary field of science.




Solar Polarization


Book Description

Much progress has been made in recent years in understanding the complex physics of polarized radiation in the sun and stars. This physics includes vector radiative transfer and spectral line formation in the presence of magnetic fields, scattering theory and coherence effects, partial redistribution and turbulent magnetic fields, numerical techniques and Stokes inversion, as well as concepts for polarimetric imaging with a precision limited only by photon statistics. The present volume gives a comprehensive and up-to-date account of this rapidly evolving field of science.




Solar Polarization


Book Description

Novel instruments for high-precision imaging polarimetry have opened new possibilities, including for exploring effects in radiative scattering, atomic physics, spectral line formation, and radiative transfer. This volume gives a comprehensive and up-to-date account of this rapidly evolving and interdisciplinary field of science.




Solar Magnetic Fields


Book Description

Magnetic fields are responsible for much of the variability and structuring in the universe, but only on the Sun can the basic magnetic field related processes be explored in detail. While several excellent textbooks have established a diagnostic foundation for exploring the physics of unmagnetized stellar atmospheres through spectral analysis, no corresponding treatise for magnetized stellar atmospheres has been available. The present monograph fills this gap. The theoretical foundation for the diagnostics of stellar magnetism is developed from first principles in a comprehensive way, both within the frameworks of classical physics and quantum field theory, together with a presentation of the various solar applications. This textbook can serve as an introduction to solar and stellar magnetism for astronomers and physicists at the graduate or advanced undergraduate level and will also become a resource book for more senior scientists with a general interest in cosmic magnetic fields.




Polarization Spectra of Centimeter-wavelength Solar Bursts Using Whole-sun Observations


Book Description

The physics of microwave-burst emission is briefly examined to give the rationale for investigating polarization spectra. The instruments used to carry out the 9.4 GHz and 7 GHz circular-polarization measurements and the 5 GHz Stokes-parameter measurements are described. A survey of the August 1972 to December 1973 period produced a table of 45 bursts, from which some limited results were obtained. About 75 to 80 percent of all bursts are circularly polarized, with varying polarization over the 5 to 9.4 GHz range. For most bursts where the circular polarization pc increases toward the upper or lower end of the 5 to 9.4 GHz range, the total intensity I also increases in that direction. The few bursts having a pc sense reversal in the 5 to 9.4 GHz range also have a spectral maximum of I at roughly the same frequency. Some simplified explanations of the results are presented.




Magnetic Coupling between the Interior and Atmosphere of the Sun


Book Description

Solar physics in India has a tradition that can be traced to the setting up of the Kodaikanal Observatory in 1899 when the Madras Observatory was relocated to a high altitude site with a view to initiate observations of the sun. This conference on Magnetic Coupling between the Interior and the Atmosphere of the Sun during 2–5 December 2008 was planned to coincide with centenary of the Evershed effect discovery at Kodaikanal in 1909. The aim of this meeting was to bring to a critical focus a comprehensive - derstanding of the important issues pertaining to solar magnetism with particular emphasis on the various MHD processes that operate in the solar atmosphere. The current status of magnetic eld measurements and their implications in the light of recenttheoriesandnumericalmodelingthataddressthe fundamentalscalesandp- cessesinthehighlymagnetizedturbulentplasmawerereviewedduringthismeeting. The meeting was timely for the following reasons: Space observations such as from SOHO and TRACE have provided a wealth of multiwavelength observations onprocessesoccurringinregionsofthe atmosphereextendingfromthe photosphere up to the outer corona. With the launch of Hinode and STEREO in 2006 and of SDO (Solar Dynamics Observatory) shortly, this conference provided a platform for in-depth discussions on new results from various space missions as well as a comparison with ground-based observing facilities such as the Swedish 1-m Solar Telescope. Using sophisticated image processing techniques, such telescopes r- tinelygenerateobservationswitharesolutionbetterthan0. 1arcsec,therebyyielding more informative diagnostics for instance of the microstructure of ux tubes.




Physics of the Invisible Sun


Book Description

Physics of the invisible Sun: Instrumentation, Observations, and Inferences provides a new updated perspectives of the dramatic developments in solar physics mainly after the advent of the space era. It focusses on the instrumentation exploiting the invisible windows of the electromagnetic spectrum for observing the outer, fainter layers of the Sun. It emphasizes on the several technical and observational challenges and proceeds to discuss the discoveries related to energetic phenomena occurring in the transition region and corona. The book begins with giving a brief glimpse of the historical developments during the pre-, and post-telescopic periods of visible and spectroscopic techniques, ground-based optical and radio observing sites. Various types of telescopes and back-end instrumentation are presented based on photometry, spectroscopy, and polarimetry using the Zeeman and Hanle effects for measurement of magnetic fields, and Doppler effect for radial velocity measurements. The book discusses theoretical and observational inferences based on detection of solar neutrinos, and helioseismology as the probes of the hidden solar interior, and tests of solar standard models. The characteristic properties and observational signatures of global solar p- and g-oscillations modes, developments in local helioseismology and asteroseismology are discussed. The role of the solar magnetic field and differential rotation in the activity and magnetic cycles, prediction methodologies, and dynamo models are described. Observing the Sun in IR at the longer, and the UV, EUV, XUV, X-rays, and gamma-rays at the shorter wavelengths are covered in detail. Observational challenges at each of these wavelengths are presented followed by the instrumentation for detection and imaging that have resulted in enhancing the understanding of various solar transient phenomena, such as, flares and CMEs. The outer most corona is described as a dynamic, expanding component of the Sun from the theoretical and observational perspectives of the solar wind. It then discusses the topics of the Interplanetary magnetic field, slow and fast solar wind, interaction with magnetised and non-magnetised objects of the solar system, the space weather and the physics of the heliosphere. The chapter on the future directions in solar physics presents a brief overview of the new major facilities in various observing windows, and the future possibilities of observing the Sun from ground and vantage locations in space. Features: Systematic overview of the developments in instrumentation, observational challenges and inferences derived from ground-based and space-borne solar projects. Advances in the understanding about the solar interior from neutrinos and helioseismology. Recent research results and future directions from ground- and space-based observations. This book may serve as a reference book for scientific researchers interested in multi-wavelength instrumentation and observational aspects of solar physics. It may also be used as a textbook for a graduate-level course.




Polarimetry of Stars and Planetary Systems


Book Description

Summarising the striking advances of the last two decades, this reliable introduction to modern astronomical polarimetry provides a comprehensive review of state-of-the-art techniques, models and research methods. Focusing on optical and near-infrared wavelengths, each detailed, up-to-date chapter addresses a different facet of recent innovations, including new instrumentation, techniques and theories; new methods based on laboratory studies, enabling the modelling of polarimetric characteristics for a wide variety of astronomical objects; emerging fields of polarimetric exploration, including proto-planetary and debris discs, icy satellites, transneptunian objects, exoplanets, and the search for extraterrestrial life; and unique results produced by space telescopes, and polarimeters aboard exploratory spacecraft. With contributions from an international team of accomplished researchers, this is an ideal resource for astronomers and researchers working in astrophysics, earth sciences, and remote sensing keen to learn more about this valuable diagnostic tool. The book is dedicated to the memory of renowned polarimetrist Tom Gehrels.







Polarization in Spectral Lines


Book Description

The scientific research based on spectropolarimetric techniques is undergoing a phase of rapid growth. Instruments of unprecedented sensitivity are nowadays available, particularly for solar observations. To fully exploit the rich diagnostic content of such observations, it is necessary to understand the physical mechanisms involved in the generation and transfer of polarized radiation in astrophysical (or laboratory) plasmas. After an introductory part based on classical physics, this book tackles the subject by a rigorous quantum-mechanical approach. The transfer equations for polarized radiation and the statistical equilibrium equations for the atomic density matrix are derived directly from the principles of Quantum Electrodynamics. The two sets of equations are then used to present a number of applications, mainly concerning the diagnostics of solar magnetic fields. This book is primarily addressed to scientists working in the field of spectropolarimetry. It may also serve as a textbook for a course at the graduate or advanced undergraduate level.