Particle Acceleration And Kinematics In Solar Flares

Author : Markus Aschwanden
Publisher : Springer Science & Business Media
Page : 233 pages
File Size : 40,5 Mb
Release : 2013-03-09
Category : Science
ISBN : 9789401725415

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Particle Acceleration and Kinematics in Solar Flares by Markus Aschwanden Pdf

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.

Author : Marina Battaglia
Publisher : Cuvillier Verlag
Page : 162 pages
File Size : 55,5 Mb
Release : 2009-02-05
Category : Science
ISBN : 9783736928800

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Particle kinematics in solar flares: observations and theory by Marina Battaglia Pdf

This thesis is devoted to the study of particle acceleration and propagation processes in solar flares. Solar flares are amongst the most powerful and energetic activity phenomena our Sun exhibits. They release energy of the order of 1032 erg in seconds to minutes. In the process, electrons and protons are accelerated to relativistic energies, making flares very efficient particle accelerators. The most compelling observational signatures of flares can be found in X-rays and extreme ultra-violet wavelengths. Due to atmospheric absorption, those wavelengths can only be studied from space. Since the beginning of the space age, countless flares have been observed by satellites. The present work is largely based on observations by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI), an X-ray satellite which has been observing the Sun since February 2002. It is a NASA mission with substantial Swiss hardware and software contribution. Using RHESSI observations of flares of different intensity, a deeper understanding of the particle transport and energy transport processes in flare loops, as well as the acceleration site and acceleration mechanism is sought. The time evolution of images and spectra is studied along with the quantitative relations between X-ray sources observed in the corona (coronal sources) and from the chromosphere (footpoints). The spectral relations found between coronal sources and footpoints are compared to the so-called ``intermediate thin-thick target model'', which was based on observations by the satellite Yohkoh. We show that the spectral relations between coronal sources and footpoints observed with RHESSI cannot be explained by the intermediate thin-thick target model. In a next step, return currents in the flare loop were considered. With this extension to the existing model, the spectra of the coronal source and the footpoints, as well as the relations between them can be explained, indicating the importance of return currents in flare loops. In a second part, observations of so-called ``pre-flares'' are presented. This earliest phase of a flare cannot be explained by the standard flare model of chromospheric evaporation which involves energy transport and deposition in the chromosphere by beams of accelerated electrons. In pre-flares, an increase in density and emission measure is observed, indicating that chromospheric evaporation is occurring. However, no observational signatures of fast electrons are found. We show that if energy is transported by means of thermal conduction instead of an electron beam, the observations can explained.

Author : B.V. Somov
Publisher : Springer Science & Business Media
Page : 255 pages
File Size : 45,7 Mb
Release : 2012-12-06
Category : Science
ISBN : 9789401123969

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Physical Processes in Solar Flares by B.V. Somov Pdf

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.

Author : Brian R. Dennis,Takeo Kosugi,Robert P. Lin
Publisher : Unknown
Page : 376 pages
File Size : 40,6 Mb
Release : 2003
Category : Particle acceleration
ISBN : UOM:39015057327739

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Energy Release and Particle Acceleration in the Solar Atmosphere by Brian R. Dennis,Takeo Kosugi,Robert P. Lin Pdf

Author : Donald V. Reames
Publisher : Springer
Page : 127 pages
File Size : 52,8 Mb
Release : 2017-03-10
Category : Science
ISBN : 9783319508719

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Solar Energetic Particles by Donald V. Reames Pdf

This concise primer introduces the non-specialist reader to the physics of solar energetic particles (SEP) and systematically reviews the evidence for the two main mechanisms which lead to the so-called impulsive and gradual SEP events. More specifically, the timing of the onsets, the longitude distributions, the high-energy spectral shapes, the correlations with other solar phenomena (e.g. coronal mass ejections), as well as the all-important elemental and isotopic abundances of SEPs are investigated. Impulsive SEP events are related to magnetic reconnection in solar flares and jets. The concept of shock acceleration by scattering on self-amplified Alfvén waves is introduced, as is the evidence of reacceleration of impulsive-SEP material in the seed population accessed by the shocks in gradual events. The text then develops processes of transport of ions out to an observer. Finally, a new technique to determine the source plasma temperature in both impulsive and gradual events is demonstrated. Last but not least the role of SEP events as a radiation hazard in space is mentioned and a short discussion of the nature of the main particle telescope designs that have contributed to most of the SEP measurements is given.

Author : A. Gordon Emslie,Brian R. Dennis,Robert P. Lin,Hugh Hudson
Publisher : Springer
Page : 0 pages
File Size : 54,8 Mb
Release : 2011-08-24
Category : Science
ISBN : 1461430739

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High-Energy Aspects of Solar Flares by A. Gordon Emslie,Brian R. Dennis,Robert P. Lin,Hugh Hudson Pdf

This edited volume describes many aspects of current research on solar flares, emphasizing recent progress in understanding their X-ray and gamma-ray emissions. Several of the chapters deal comprehensively with the problems of particle acceleration, conversion of particle energy into various forms of radiation, and the inference of physical processes from observations. Other chapters deal with the full breadth and richness of flare observations, including microflares and nanoflares. This volume is aimed at graduate students and researchers in solar physics and space science. Previously published in Space Science Reviews journal, Vol. 159/1-4, 2011.

Author : Jun-Ichi Sakai,C. de Jager
Publisher : Springer Science & Business Media
Page : 198 pages
File Size : 45,6 Mb
Release : 2012-12-06
Category : Science
ISBN : 9789400903319

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Solar Flares and Collisions between Current-Carrying Loops by Jun-Ichi Sakai,C. de Jager Pdf

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.

Author : Mukul Ranjan Kundu,Bruce Woodgate
Publisher : Unknown
Page : 450 pages
File Size : 51,6 Mb
Release : 1987
Category : Solar flares
ISBN : UOM:39015015941050

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Energetic Phenomena on the Sun by Mukul Ranjan Kundu,Bruce Woodgate Pdf

Author : Karl-Ludwig Klein
Publisher : Springer
Page : 319 pages
File Size : 44,5 Mb
Release : 2008-01-11
Category : Science
ISBN : 9783540362425

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Energy Conversion and Particle Acceleration in the Solar Corona by Karl-Ludwig Klein Pdf

The conversion of energy generated in the Sun's interior creates its hot corona and a wealth of dynamical phenomena such as flares and mass ejections. Based on recent significant progress in understanding magnetic reconnection and a wealth of new observations of energetic particle signatures from the sun, the present volume reviews the current theoretical and experimental status in the field. Paying attention to both the details and the broader picture, this book addresses both the experienced researcher as well as non-specialist researchers from related areas and postgraduate students.

Author : National Aeronautics and Space Adm Nasa
Publisher : Unknown
Page : 36 pages
File Size : 53,5 Mb
Release : 2018-10-22
Category : Electronic
ISBN : 1729076289

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Acceleration of Electrons and Ions by Strong Lower-Hybrid Turbulence in Solar Flares by National Aeronautics and Space Adm Nasa Pdf

One of the outstanding problems in solar flare theory is how to explain the 10-20 keV and greater hard x-ray emissions by a thick target bremsstrahlung model. The model requires the acceleration mechanism to accelerate approximately 10(exp 35) electrons sec(exp -l) with comparable energies, without producing a large return current which persists for long time scales after the beam ceases to exist due to Lenz's law, thereby, producing a self-magnetic field of order a few mega-Gauss. In this paper, we investigate particle acceleration resulting from the relaxation of unstable ion ring distributions, producing strong wave activity at the lower hybrid frequency. It is shown that strong lower hybrid wave turbulence collapses in configuration space producing density cavities containing intense electrostatic lower hybrid wave activity. The collapse of these intense nonlinear wave packets saturate by particle acceleration producing energetic electron and ion tails. There are several mechanisms whereby unstable ion distributions could be formed in the solar atmosphere, including reflection at perpendicular shocks, tearing modes, and loss cone depletion. Numerical simulations of ion ring relaxation processes, obtained using a 2 1/2-D fully electromagnetic, relativistic particle in cell code are discussed. We apply the results to the problem of explaining energetic particle production in solar flares. The results show the simultaneous acceleration of both electrons and ions to very high energies: electrons are accelerated to energies in the range 10-500 keV, while ions are accelerated to energies of the order of MeVs, giving rise to x-ray emission and gamma-ray emission respectively. Our simulations also show wave generation at the electron cyclotron frequency. We suggest that these waves are the solar millisecond radio spikes. The strong turbulence collapse process leads to a highly filamented plasma producing many localized regions for particle acceleration and resulting in ...

Author : Gérard Trottet,N. Vilmer
Publisher : Unknown
Page : 246 pages
File Size : 54,6 Mb
Release : 2005
Category : Heliosphere
ISBN : UOM:39015062464816

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Energy Release and Particle Acceleration at the Sun and in the Heliosphere by Gérard Trottet,N. Vilmer Pdf

Author : Gang Li
Publisher : American Institute of Physics
Page : 468 pages
File Size : 46,8 Mb
Release : 2008-09-12
Category : Science
ISBN : UCSD:31822037194040

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Particle Acceleration and Transport in the Heliosphere and Beyond by Gang Li Pdf

All papers have been peer-reviewed. Our star is a very effective particle accelerator. Energies up to GeVs have been observed in Solar energetic particle events. These events are often associated with solar flares and/or Coronal Mass Ejections. Understanding how particles are accelerated in these phenomena has been an outstanding problem in space plasma physics for a long time. Part of the reason is its practical (e.g. Space weather) and fundamental (cosmic ray origin) importance. In this conference we review recent progresses on this problem, with a balance between observations, theories and numerical simulations. Specific topics include 1) particle acceleration at flare site, 2) turbulence properties of the solar wind, 3) particle acceleration and transport in the inner heliosphere, 4) particle acceleration at the termination shock and heliosheath, and 5) particle acceleration at supernova remnant shocks.

Author : Karl L. Klein,Alexander L. MacKinnon
Publisher : Springer
Page : 284 pages
File Size : 52,9 Mb
Release : 2007-09-26
Category : Science
ISBN : 9783540715702

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The High Energy Solar Corona: Waves, Eruptions, Particles by Karl L. Klein,Alexander L. MacKinnon Pdf

An outgrow of an earlier workshop held by the community of European Solar Radio Astronomers (CESRA), this topical volume collects reviews on the current multiwavelength findings and perspectives from the space missions RHESSI, TRACE and SOTTO. The aspects of solar physics dealt with are particle acceleration during flares, large-scale disturbances, and coronal plasma physics.

Author : R. Ramaty,Natalie Mandzhavidze,Xin-Min Hua
Publisher : A I P Press
Page : 568 pages
File Size : 55,6 Mb
Release : 1996
Category : Science
ISBN : UOM:39015037842054

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High-Energy Solar Physics by R. Ramaty,Natalie Mandzhavidze,Xin-Min Hua Pdf

Annotation Reports on recent developments in the study of solar flares, emphasizing work at high energies and addressing such persistent problems of the processes of flare energy release, particle acceleration, and accelerated particle transport and interaction. After reviewing the history of understanding about solar flare particle acceleration since 1942, the 53 papers cover energetic charged particles, x-rays, radio emission, and the theory of particle acceleration. Among the specific topics are high energy particle in interplanetary space on 11 June 1991, the spectral evolution of an intense gamma-ray line flare, nonthermal radio emission from coronal x-ray structures, and the formation of the helium-3 spectrum in impulsive solar flares. No subject index. Annotation c. by Book News, Inc., Portland, Or.

Author : Guangli Huang,Victor F. Melnikov,Haisheng Ji,Zongjun Ning
Publisher : Springer
Page : 424 pages
File Size : 51,7 Mb
Release : 2018-01-31
Category : Science
ISBN : 9789811028694

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Solar Flare Loops: Observations and Interpretations by Guangli Huang,Victor F. Melnikov,Haisheng Ji,Zongjun Ning Pdf

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.