Download or read book A Study of Oscillations in Solar Active Regions written by Ram Ajor Maurya and published by LAP Lambert Academic Publishing. This book was released on 2014-05-16 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar active regions (ARs) are three-dimensional magnetic structures extending from deep sub-photosphere to coronal heights. These ARs are responsible for producing most of the energetic transients, such as flares and CMEs. Energetic transients are expected to excite p-mode oscillations in ARs by imparting mechanical impulse associated with their thermal expansion on the photosphere. Flare productive ARs may have distinctly different sub-photospheric properties compared to dormant ARs. We have determined the characteristic properties of local oscillation modes by applying the local helioseismic technique to several ARs. Strong evidence of substantial increase in mode amplitude are found from comparison of the pre- to the post-flare phases of energetic flares. Our study has revealed strongly twisted, sheared flows in the interior of flaring ARs having complex magnetic fields. We discovered steep gradients in meridional velocity at depths ranging from 1.5 to 5 Mm in flare productive ARs. Our study of sub-photospheric flows and photospheric magnetic fields of several ARs showed that the sub-photospheric kinetic helicity and photospheric magnetic helicity are weakly correlated.
Download or read book The Interaction of High degree P mode Oscillations with Solar Active Regions written by Douglas Clifford Braun and published by . This book was released on 1988 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of Oscillations and Flows in Solar Magnetic Active Regions written by Hope Thackray and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Frequency Oscillations in a Solar Active Region Coronal Loop written by D. R. Williams and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of the Sun written by P.A. Sturrock and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume, together with its two companion volumes, originated in a study commis sioned by the United States National Academy of Sciences on behalf of the National Aeronautics and Space Administration. A committee composed of Tom Holzer, Dimitri Mihalas, Roger Ulrich and myself was asked to prepare a comprehensive review of current knowledge concerning the physics of the Sun. We were fortunate in being able to persuade many distinguished scientists to gather their forces for the preparation of 21 separate chapters covering not only solar physics but also relevant areas of astrophysics and solar-terrestrial relations. It proved necessary to divide the chapters into three separate volumes that cover three different aspects of solar physics. Volumes II and III are concerned with 'The Solar Atmosphere' and with 'Astrophysics and Solar-Terrestrial Relations'. This volume is devoted to 'The Solar Interior', except that the volume begins with one chapter reviewing the contents of all three volumes. Our study of the solar interior includes a review of nuclear, atomic, radiative, hydrodynamic and hydromagnetic processes, together with reviews of three areas of active current investigation: the dynamo mechanism, internal rotation and magnetic fields, and oscillations. The last topic, in particular, has emerged in recent years as one of the most exciting areas of solar research.
Download or read book Structure and Development of Solar Active Regions written by International Astronomical Union and published by . This book was released on 1968 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar Oscillations in Magnetic Regions written by Christopher Hanson and published by . This book was released on 2014 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the 50 years of helioseismology, we have gained an extensive understanding into the physical processes present within our sun. With the aid of high resolution observations and increased computational power, the current body of understanding is rapidly growing. However, there are still many questions left answered today. In this thesis, we will address two phenomena in order to shed light on their related open questions. In the first part, we will examine the scattering regimes that exist within bundles of thin magnetic flux tubes. In particular, we will address the question of how magnetic plage can absorb large amounts of wave energy and whether the resultant scattered wave field can be used to infer the magnetic field structure. The second phenomenon concerns the seismic sources that are situated within acoustic power halos and what role of the magnetic field has in enhancing these sources. In addressing the multiple scattering regime, a semi-analytical model was developed in order to model the scattering between numerous thin flux tubes situated within a stratified atmosphere. We have used a method originally designed for oceanic wave scattering, and applied it to a solar context. While to some extent this has been done in the past, we further develop the model to include the scattering of all possible modes between thin magnetic flux tubes. In doing so, we outline and address a mathematical error in the original formalism, that was not apparent until previous results were compared to recent numerical studies. Numerous case studies are then examined, ranging from the simple case of two interacting tubes, to large numbers of closely packed tubes. Various parameters are explored and the effect these have on the scattering regime is reported. Our results compare quite well with numerical and observational studies, and this model presents a significant step forward in understanding how the scattered wave field can be used to infer the internal constitution of a slender magnetic field structure.On addressing the second phenomenon, we employ the helioseismic holography technique to examine the enhanced seismic sources that are situated within the acoustic power halo that surrounds complex active regions. We examine three active regions using SDO data and apply strict statistical precautions in our analysis. The relationship between the seismic sources and the magnetic field is explored, with a strong correlation found between seismic enhancement and quasi-horizontal fields of intermediate strength. Additionally, the most intense seismic emitters (acoustic glories) were found to be located within fields very close to horizontal. The relationship between the seismic source halos and the commonly used local acoustic power maps is also explored, with large similarities reported. We found that the greatest difference between the two types of halos occurs within the high frequency (9 mHz) regime. The results of this observational study agree with other recent studies, however this study presents a significant advancement on previous holography studies.
Download or read book Solar Interior and Atmosphere written by Arthur N. Cox and published by University of Arizona Press. This book was released on 1991-12 with total page 1444 pages. Available in PDF, EPUB and Kindle. Book excerpt: Observational data derived from the world's largest solar telescopes are correlated with theoretical discussions in nuclear and atomic physics by contributors representing a wide range of interests in solar research.
Download or read book Study of the Solar Cycle from Space written by and published by . This book was released on 1980 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solar and Space Weather Radio Physics written by Bin Chen and published by Frontiers Media SA. This book was released on 2021-07-28 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics of the Sun written by P a Sturrock and published by . This book was released on 1985-12-31 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Sun as a Variable Star Solar and Stellar Irradiance Variations written by Judit M. Pap and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 321 pages. Available in PDF, EPUB and Kindle. Book excerpt: The IAU Colloquium No. 143 "The Sun as a Variable Star: Solar and Stellar Irradiance Variations" was held on June 20 - 25, 1993 at the Clarion Harvest House, Boulder, Colorado, USA. The main objective of this Colloquium was to review the most recent results on the observations, theoretical interpreta tions, and empirical and physical models of the variations observed in solar and stellar irradiances. A special emphasis of the Colloquium was to discuss the results gained on the climatic impact of solar irradiance variability. The study of changes in solar and stellar irradiances has been of high interest for a long time. Determining the absolute value of the luminosity of stars with different ages is a crucial question for the theory of stellar evolu tion and energy production of stellar interiors. Observations of the temporal changes of solar and stellar irradiances - in the entire spectral band and at different wavelengths - provide an additional tool for studying the physical processes below the photosphere and in the solar- stellar atmospheres. Since the Sun's radiative output is the main driver of the physical processes with in the Earth's atmosphere, the study of irradiance changes is an extremely important issue for climatic studies as well. Climatic models show that small, but persistent changes in solar irradiance may influence the Earth's climate.
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Introduction to Waves and Oscillations in the Sun written by A. Satya Narayanan and published by Springer Science & Business Media. This book was released on 2012-09-15 with total page 232 pages. Available in PDF, EPUB and Kindle. Book excerpt: “An Introduction to Waves and Oscillations in the Sun” is intended for students and researchers who work in the area of solar and astrophysics. This book contains an introduction to the Sun, basics of electrodynamics, magneto-hydrodynamics for force-free and current-free fields. It deals with waves in uniform media with relevance to sound waves and Alfven waves, and with waves in non-uniform media like surface waves or waves in a slab and cylindrical geometry. It also touches on instabilities in fluids and observational signatures of oscillations. Finally, there is an introduction to the area of helio-seismology, which deals with the internal structure of the Sun.
Download or read book The Solar Activity Cycle written by André Balogh and published by Springer. This book was released on 2015-04-16 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: A collection of papers edited by four experts in the field, this book sets out to describe the way solar activity is manifested in observations of the solar interior, the photosphere, the chromosphere, the corona and the heliosphere. The 11-year solar activity cycle, more generally known as the sunspot cycle, is a fundamental property of the Sun. This phenomenon is the generation and evolution of magnetic fields in the Sun’s convection zone, the photosphere. It is only by the careful enumeration and description of the phenomena and their variations that one can clarify their interdependences. The sunspot cycle has been tracked back about four centuries, and it has been recognized that to make this data set a really useful tool in understanding how the activity cycle works and how it can be predicted, a very careful and detailed effort is needed to generate sunspot numbers. This book deals with this topic, together with several others that present related phenomena that all indicate the physical processes that take place in the Sun and its exterior environment. The reviews in the book also present the latest theoretical and modelling studies that attempt to explain the activity cycle. It remains true, as has been shown in the unexpected characteristics of the first two solar cycles in the 21st century, that predictability remains a serious challenge. Nevertheless, the highly expert and detailed reviews in this book, using the very best solar observations from both ground- and space based telescopes, provide the best possible report on what is known and what is yet to be discovered. Originally published in Space Science Reviews, Vol 186, Issues 1-4, 2014.
Download or read book Solar and Stellar Flares written by Lyndsay Fletcher and published by Springer. This book was released on 2016-12-21 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a collection of research articles on the subject of solar flares and flares on other cool stars, which are currently extensively studied using new ground- and space-based instruments, together with highly sophisticated numerical simulations. The collection memorializes the work of a pioneer in the study of solar physics, Professor Zdenek Švestka (1925 Prague – 2013 Bunschoten), a leading expert in the field of solar flares and the co-founder and Editor-in-Chief of the journal Solar Physics. The book contains many contributions to the conference “Solar and Stellar Flares: Observations, simulations and synergies”, held in Prague during 23 – 27 June 2014, organised in honor and memory of Professor Švestka. Originally published as Topical Issue of Solar Physics, Vol. 290, Issue 12, 2015.
Download or read book The SOHO Mission written by Bernhard Fleck and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: SOHO, the Solar and Heliospheric Observatory, is a project of international cooperation between ESA and NASA to study the Sun, from its deep core to the outer corona, and the solar wind. To achieve its scientific goals it carries a complement of twelve sophisticated, state-of-the-art instruments. Three helioseismology instruments are expected to provide unique data for the study of the structure and dynamics of the solar interior, from the very deep core to the outermost layers of the convection zone. A set of five complementary remote sensing instruments, consisting of EUV and UV imagers, spectrographs and coronagraphs, will give us our first comprehensive view of the outer solar atmosphere and corona, leading to a better understanding of the enigmatic coronal heating and solar wind acceleration processes. Finally, three experiments will complement the remote sensing observations by making in-situ measurements of the composition and energy of the solar wind and charged energetic particles. This volume contains detailed descriptions of all the twelve instruments on board SOHO. Also included are an overview paper and a description of the SOHO ground system, science operations and data products. The aim of these papers is to make the broader scientific community, and in particular potential guest investigators, aware of the scientific objectives and capabilities of the SOHO payload and to provide a reference document for the various instruments.
