Download or read book Radiation Hydrodynamics in Solar Flares written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar flares are rather violent and extremely complicated phenomena, and it should be made clear at the outset that a physically complete picture describing all aspects of flares does not exist. From the wealth of data which is available, it is apparent that many different types of physical processes are involved during flares: energetic particle acceleration, rapid magnetohydrodynamic motion of complex field structures, magnetic reconnection, violent mass motion along magnetic field lines, and the heating of plasma to tens of millions of degrees, to name a few. The goal of this paper is to explore just one aspect of solar flares, namely, the interaction of hydrodynamics and radiation processes in fluid being rapidly heated along closed magnetic field lines. The models discussed are therefore necessarily restrictive, and will address only a few of the observed or observable phenomena. 46 refs., 6 figs.
Download or read book Ionospheric Effects of Solar Flares written by Hermine Vloemans and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sudden Ionospheric Disturbances resulting from an interaction of the Solar Flare radiation with the constituents of the upper atmosphere constitute one of the three major aspects of ground level monitoring of solar flares -the other two being optical observations of flares, and the observations of solar bursts in radio wavelengths. SIDs, therefore, form a major part of flare monitoring programme in many observatories. Unlike the other two, however, the ionospheric effects of flares provide one major additional source of interest - the reaction of the ionospheric plasma to an impulsive ionization. The high atmosphere provides a low pressure laboratory without walls in which a host of reactions occur between electrons, ions and neutral particles. The resulting products and their distributions may bear no resemblance to those of the primary neutral constituents or their direct ionization products. The variations with the time of the day, with season and with solar activity that form the bulk of the ionospheric measurements are too slow to allow any insight into the nature of these ionospheric reactions whose lifetimes are often very short. The relaxation time of the ionospheric ionization is only a few minutes or fraction of a minute in the lower ionosphere and in the E-region and is about 30 min to an hour at 300 km. The flares provide a sudden short impulse comparable to these time scales.
Download or read book Physical Processes in Solar Flares written by B.V. Somov and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar flares are very complex electromagnetic phenomena of a cataclysmic nature. Particles are accelerated to very high velocities and a variety of physical processes happen inside and outside flares. These processes can be studied by a large number of techniques from Earth and from space. The aim is to discover the physics behind solar flares. This goal is complicated because information about the flare mechanism can be obtained only in an indirect way by studying the secondary effects. This book provides three stages in the solution of the solar flare problem. Chapter one describes the connection between observational data and theoretical concepts, where it is stressed that next to investigating flares, the related non-stationary large-scale phenomena must be studied as well. The second chapter deals with secondary physical processes, in particular the study of high-temperature plasma dynamics during impulsive heating. The last chapter presents a model built on the knowledge of the two previous chapters and it constructs a theory of non-neutral turbulent current sheets. The author believes that this model will help to solve the problem of solar flares. For solar physicists, plasma physicists, high-energy particle physicists.
Download or read book The Physics of Solar Flares written by Einar Tandberg-Hanssen and published by Cambridge University Press. This book was released on 1988-11-17 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors explore solar flares by applying physics and theoretical investigations.
Download or read book Solar Flare Loops Observations and Interpretations written by Guangli Huang and published by Springer. This book was released on 2018-01-31 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides results of analysis of typical solar events, statistical analysis, the diagnostics of energetic electrons and magnetic field, as well as the global behavior of solar flaring loops such as their contraction and expansion. It pays particular attention to analyzing solar flare loops with microwave, hard X-ray, optical and EUV emissions, as well as the theories of their radiation, and electron acceleration/transport. The results concerning influence of the pitch-angle anisotropy of non-thermal electrons on their microwave and hard X-ray emissions, new spectral behaviors in X-ray and microwave bands, and results related to the contraction of flaring loops, are widely discussed in the literature of solar physics. The book is useful for graduate students and researchers in solar and space physics.
Download or read book Solar Flares written by Zdenek Svestka and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is the first part of the originally planned publication by Z. Svestka and L. D. de Feiter 'Solar High Energy Photon and Particle Emission'. The second part, with the original title, was to be published by de Feiter in about one year from now. However, to the deep sorrow of all of us, Dr de Feiter died suddenly and unexpectedly when the present book was in print. Thus, unfortunately, de Feiter's second part may not appear. Due to the fact that the originally planned publication was divided into two parts, the present book is mainly descriptive and concerned with the flare morphology. It was expected that theoretical interpretations would be extensively developed in the second part, prepared by de Feiter. In particular, this refers to the theoretical back grounds of radio emissions, particle acceleration and particle propagation in space. Only in Chapter II, concerning the 'low-temperature' flare, do we go deeper into the theoretical interpretations, anticipating that de Feiter would have been concerned mainly with the 'high-energy' physics. Still, the book includes discussions on all important aspects of flares and thus can present the reader with a complete picture of the complex flare phenomenon. It is clear that many observed data on flares can be interpreted in different ways.
Download or read book Solar Flare Magnetic Fields and Plasmas written by Yuhong Fan and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is devoted to the dynamics and diagnostics of solar magnetic fields and plasmas in the Sun’s atmosphere. Five broad areas of current research in Solar Physics are presented: (1) New techniques for incorporating radiation transfer effects into three-dimensional magnetohydrodynamic models of the solar interior and atmosphere, (2) The connection between observed radiation processes occurring during flares and the underlying flare energy release and transport mechanisms, (3) The global balance of forces and momenta that occur during flares, (4) The data-analysis and theoretical tools needed to understand and assimilate vector magnetogram observations and (5) Connecting flare and CME phenomena to the topological properties of the magnetic field in the Solar Atmosphere. The role of the Sun’s magnetic field is a major emphasis of this book, which was inspired by a workshop honoring Richard C. (Dick) Canfield. Dick has been making profound contributions to these areas of research over a long and productive scientific career. Many of the articles in this topical issue were first presented as talks during this workshop and represent substantial original work. The workshop was held 9 – 11 August 2010, at the Center Green campus of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. This volume is aimed at researchers and graduate students active in solar physics, solar-terrestrial physics and magneto-hydrodynamics. Previously published in Solar Physics journal, Vol. 277/1, 2012.
Download or read book Radiation Hydrodynamics of the Stratified Solar Plasma written by Claudia-Veronika Meister and published by . This book was released on 2000 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ionospheric Effects of Solar Flares written by Hermine Vloemans and published by Springer. This book was released on 2012-01-07 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sudden Ionospheric Disturbances resulting from an interaction of the Solar Flare radiation with the constituents of the upper atmosphere constitute one of the three major aspects of ground level monitoring of solar flares -the other two being optical observations of flares, and the observations of solar bursts in radio wavelengths. SIDs, therefore, form a major part of flare monitoring programme in many observatories. Unlike the other two, however, the ionospheric effects of flares provide one major additional source of interest - the reaction of the ionospheric plasma to an impulsive ionization. The high atmosphere provides a low pressure laboratory without walls in which a host of reactions occur between electrons, ions and neutral particles. The resulting products and their distributions may bear no resemblance to those of the primary neutral constituents or their direct ionization products. The variations with the time of the day, with season and with solar activity that form the bulk of the ionospheric measurements are too slow to allow any insight into the nature of these ionospheric reactions whose lifetimes are often very short. The relaxation time of the ionospheric ionization is only a few minutes or fraction of a minute in the lower ionosphere and in the E-region and is about 30 min to an hour at 300 km. The flares provide a sudden short impulse comparable to these time scales.
Download or read book Solar Flares and Collisions between Current Carrying Loops written by Jun-Ichi Sakai and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this volume we compare modem observations of solar flares with results from recent theoretical research and simulation studies on current-carrying loops and their interaction. These topics have undergone rapid developments in the course of recent years. Observational results by X-ray monitoring and imaging spacecraft in the seventies and by dedicated imaging instrumentation in the satellites Solar Max imum Mission and Hinotori, launched 1980 and 1981, have shown the importance of X-ray imaging for understanding the ignition processes of solar flares. Such observations, in tum, stimulated theoretical studies, centered around the flux-tube concept. The classical idea that flares originate by interaction of current-carrying loops was developed and proved to be promising. Concepts on reconnection and coalescence of flux tubes were developed, and their consequences studied. The Yohkoh spacecraft, launched 1991, showed the overwhelming importance of coro nal flux tubes and their many possible ways of interaction. Subsequent and parallel theoretical studies and simulations, differentiating between the topology of interact ing fluxtubes, demonstrated that the mutual positioning and the way of interaction are important for the subsequent processes of energy release in flares and the many associated phenomena such as the expUlsion of jets and the emission of X -ray and microwave radiation. The new developments now enable researchers to understand and classify flares in a physically significant way. Various processes of accelera tion are active in and after flares on greatly varying timescales; these can now be distinguished and explained.
Download or read book Foundations of Radiation Hydrodynamics written by Dimitri Mihalas and published by Courier Corporation. This book was released on 2013-04-10 with total page 753 pages. Available in PDF, EPUB and Kindle. Book excerpt: Excellent, informative volume focuses on dynamics of nonradiating fluids, problems involving waves, shocks and stellar winds, physics of radiation, radiation transport, and the dynamics of radiating fluids. 1984 edition.
Download or read book Seismic Emissions from Solar Flares written by Diana Ionescu and published by . This book was released on 2010 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sun is the centre and the master of our solar system. Its power gives us light and warmth and life, but its moods can be fearsome. Sunspots, solar flares, coronal mass ejections (CME) and the plethora of other complex magnetic activities that follow the 11-year rhythm of the solar cycle can mean devastation for our technologies, from satellites, to power grids, to telecommunications. Pity the unfortunate astronaut caught unprotected in space during a solar storm!Flares are the most powerful and most dangerous events on the Sun, spewing huge quantities of radiation and particles into space, often accompanied by a CME, sometimes to pummel the Earth. Only our magnetic shield, the magnetosphere, protects us. All means must be brought to bear when studying the Sun's activity, including observations in many wavelengths from terrestrial and space-borne observatories, and the relatively new science of local helioseismology for peering beneath the surface, the photosphere. Especially during the last decade, that of Solar Cycle 23, advances in theory and technology have opened the Sun's magnetic active regions to our deeper seismic gaze.Cycle 23 was closely mapped by the Solar and Heliospheric Observatory (SOHO) orbiting between the Earth and the Sun. A fascinating discovery made with SOHO is that flares high in the Sun's corona not only project their power outwards into space, but also downwards to the photosphere, where they can cause powerful sunquakes. This thesis is devoted to sunquakes: their discovery, their characteristics, and their physics. How and why are they formed, and why do many flares not excite them? How much energy is required to produce them? And how can this unique resource of a sudden localized seismic source be used to better probe the Sun's interior? In so-doing, I present the most detailed survey yet of sunquakes and their physics.Specifically, we have used the local helioseismic technique known as helioseismic holography to detect sunquakes by imaging their acoustic sources rather than their harder-to-see expanding ripples. Nearly all known sunquakes, more than a dozen, have been discovered by us in this way. This is sufficient to begin a survey to discover which types of flares excite quakes and which do not. Using a wide range of observations over several wavelengths, we explore the effects of such features as flare area, energy, height, and spectral hardness.We have also applied a 1D radiation hydrodynamics simulation code RADYN to synthesizing the mechanisms which might create quakes. Both our survey and our simulations favour ``back-warming'', whereby the low chromosphere is suddenly heated by the flare. This energy is then quickly transferred to the adjacent photosphere producing a quake.Because seismic emission from solar flares presents by far the most localized seismic sources in the solar environment, both spatially and temporally, and flares being the only seismic generators whose operation is open to direct view, this phenomenon offers an especially opportune control facility for 21st-century helioseismology.
Download or read book Contribution of X ray and Extreme Ultraviolet Radiation of Solar Flares to Sudden Frequency Deviations written by Richard Frank Donnelly and published by . This book was released on 1969 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: High time and intensity resolution satellite measurements of X-ray and extreme ultraviolet (EUV) radiation during solar flares are studied to determine the wavelength dependence of the flare radiation responsible for sudden frequency deviations (SFD). SFD's measure the flare-induced effects in the E and F1 regions of the ionosphere and are in effect like a broadband (1-1030 Å) detector for impulsive flare enhancements. He II 303.8 Å, O V 629.7 Å, H Ly [upsilon] 972.5 Å, C III 977.0 Å, and H Ly [alpha] 1215.7 Å were found to have essentially the same time dependence as the total ionizing radiation producing SFD's, except that they decay faster than the net 1-1030 Å radiation. Flare enhancements of Fe XV 284.1 Å, Fe XVI 335.3 Å, Si XII 499.3 Å. Mg X 625.3 Å, and Ne VIII 770.4 Å, which are normally coronal lines, appear to have a much slower time dependence than the radiation responsible for SFD's. X-rays in the 0.5-3 Å range are slightly slower than the radiation responsible for SFD's during the decay stage; 1-8 Å X-ray flares are slower, especially during the decay stages; and 8-20 Å flare radiation enhancements are slower throughout the entire SFD.
Download or read book Particle Acceleration and Kinematics in Solar Flares written by Markus Aschwanden and published by Springer Science & Business Media. This book was released on 2002-09-30 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last decade we entered a new exploration phase of solar flare physics, equipped with powerful spacecraft such as Yohkoh, SoHO, and TRACE that pro vide us detail-rich and high-resolution images of solar flares in soft X-rays, hard X -rays, and extreme-ultraviolet wavelengths. Moreover, the large-area and high sensitivity detectors on the Compton GRO spacecraft recorded an unprecedented number of high-energy photons from solar flares that surpasses all detected high energy sources taken together from the rest of the universe, for which CGRO was mainly designed to explore. However, morphological descriptions of these beau tiful pictures and statistical catalogs of these huge archives of solar data would not convey us much understanding of the underlying physics, if we would not set out to quantify physical parameters from these data and would not subject these measurements to theoretical models. Historically, there has always been an unsatisfactory gap between traditional astronomy that dutifully describes the mor phology of observations, and the newer approach of astrophysics, which starts with physical concepts from first principles and analyzes astronomical data with the goal to confirm or disprove theoretical models. In this review we attempt to bridge this yawning gap and aim to present the recent developments in solar flare high-energy physics from a physical point of view, structuring the observations and analysis results according to physical processes, such as particle acceleration, propagation, energy loss, kinematics, and radiation signatures.
Download or read book Solar Flare Magnetic Fields and Plasmas written by Yuhong Fan and published by Springer Science & Business Media. This book was released on 2012-03-28 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is devoted to the dynamics and diagnostics of solar magnetic fields and plasmas in the Sun’s atmosphere. Five broad areas of current research in Solar Physics are presented: (1) New techniques for incorporating radiation transfer effects into three-dimensional magnetohydrodynamic models of the solar interior and atmosphere, (2) The connection between observed radiation processes occurring during flares and the underlying flare energy release and transport mechanisms, (3) The global balance of forces and momenta that occur during flares, (4) The data-analysis and theoretical tools needed to understand and assimilate vector magnetogram observations and (5) Connecting flare and CME phenomena to the topological properties of the magnetic field in the Solar Atmosphere. The role of the Sun’s magnetic field is a major emphasis of this book, which was inspired by a workshop honoring Richard C. (Dick) Canfield. Dick has been making profound contributions to these areas of research over a long and productive scientific career. Many of the articles in this topical issue were first presented as talks during this workshop and represent substantial original work. The workshop was held 9 – 11 August 2010, at the Center Green campus of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. This volume is aimed at researchers and graduate students active in solar physics, solar-terrestrial physics and magneto-hydrodynamics. Previously published in Solar Physics journal, Vol. 277/1, 2012.
Download or read book Energetic Phenomena on the Sun written by Mukul Ranjan Kundu and published by . This book was released on 1987 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combining Hydrodynamic Modeling with Nonthermal Test Particle Tracking to Improve Flare Simulations written by Henry deGraffenried Winter (III.) and published by . This book was released on 2009 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar flares remain a subject of intense study in the solar physics community. These huge releases of energy on the Sun have direct consequences for humans on Earth and in space. The processes that impart tremendous amounts of energy are not well understood. In order to test theoretical models of flare formation and evolution, state of the art, numerical codes must be created that can accurately simulate the wide range of electromagnetic radiation emitted by flares. A direct comparison of simulated radiation to increasingly detailed observations will allow scientists to test the validity of theoretical models. To accomplish this task, numerical codes were developed that can simulate both the thermal and nonthermal components of a flaring plasma, their interactions, and their emissions. The HYLOOP code combines a hydrodynamic equation solver with a nonthermal particle tracking code in order to simulate the thermal and nonthermal aspects of a flare. A solar flare was simulated using this new code with a static atmosphere and with a dynamic atmosphere, to illustrate the importance of considering hydrodynamic effects on nonthermal beam evolution. The importance of density gradients in the evolution of nonthermal electron beams was investigated by studying their effects in isolation. The importance of the initial pitch-angle cosine distribution to flare dynamics was investigated. Emission in XRT filters were calculated and analyzed to see if there were soft X-ray signatures that could give clues to the nonthermal particle distributions. Finally the HXR source motions that appeared in the simulations were compared to real observations of this phenomena.
