Solar Flares As Natural Particle Accelerators
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Solar Flares As Natural Particle Accelerators
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Author : Wei Liu
language : en
Publisher:
Release Date : 2008-07-01
Solar Flares As Natural Particle Accelerators written by Wei Liu and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008-07-01 with Science categories.
Solar flares, which have significant space weather consequences, are natural particle accelerators and one of the most spectacular phenomena of solar activity. RHESSI is the most advanced solar X-ray and gamma-ray mission ever flown and has opened a new era in solar flare research following its launch in 2002. This book offers a glimpse of this active research area from a high-energy perspective and contains a comprehensive guideline for RHESSI data analysis. Its main theme is the investigation of particle acceleration and transport in solar flares. The strength of this book lies in its well-balanced account of the latest X-ray observations and theoretical models. The observational focus is on the morphology and spectra of imaged X-ray sources produced by nonthermal electrons or hot plasma. The modeling takes the novel approach of combining the Fokker-Planck treatment of the accelerated particles with the hydrodynamic treatment of the heated atmosphere. Applications of this modeling technique reach beyond the Sun to other exotic environments in the universe, such as extrasolar planetary auroras, stellar flares, and flares on accretion disks around neutron stars and black holes.
Particle Acceleration And Kinematics In Solar Flares
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Author : Markus Aschwanden
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-03-09
Particle Acceleration And Kinematics In Solar Flares written by Markus Aschwanden and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-03-09 with Science categories.
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.
Observations And Simulations Of Particle Acceleration In Solar Flares
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Author : Peter Messmer
language : en
Publisher:
Release Date : 2001
Observations And Simulations Of Particle Acceleration In Solar Flares written by Peter Messmer and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2001 with Particle acceleration categories.
Particle Kinematics In Solar Flares Observations And Theory
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Author : Marina Battaglia
language : en
Publisher: Cuvillier Verlag
Release Date : 2009-02-05
Particle Kinematics In Solar Flares Observations And Theory written by Marina Battaglia and has been published by Cuvillier Verlag this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009-02-05 with Science categories.
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.
Stochastic Acceleration Of Electrons By Turbulence In Solar Flares
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Author : Qingrong Chen
language : en
Publisher:
Release Date : 2013
Stochastic Acceleration Of Electrons By Turbulence In Solar Flares written by Qingrong Chen and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with categories.
Solar flares are among the most powerful explosions and most efficient particle accelerators in the solar system. The model of stochastic acceleration by plasma turbulence has been very instrumental in explaining the observed high-energy radiations and particles from solar flares. In this thesis, we aim to better constrain the electron acceleration and scattering processes by turbulence from hard X-ray imaging spectroscopic observations of solar flares. By utilizing the leaky box Fokker-Planck equation and the thick target equation describing particle acceleration and transport, we derive analytical formulas for the stochastic acceleration model quantities directly in terms of the accelerated and escaping particle spectra. Based on the hard X-ray radiating electron flux spectral images via regularized inversion, we determine the timescales for electron escape, pitch angle scattering, energy diffusion, and direct acceleration in two intense solar flares with a high-energy loop-top coronal source observed by the RHESSI mission. The existence of distinct coronal hard X-ray sources up to 100-150 keV in the impulsive phase indicates efficient confinement of high-energy electrons in the corona. The results that the electron escape time increases with energy and the acceleration time and scattering time exhibit very different energy dependences contradict existing predictions for stochastic acceleration due to wave-particle resonant interactions. The discrepancy between the observations and the acceleration model could be alleviated if the turbulence spectrum is much steeper than commonly assumed. A more plausible explanation for such events is that the escape of electrons from the loop-top acceleration region is not diffusive in nature due to scattering, but is affected by magnetic mirroring.
Particle Acceleration And Trapping In Solar Flares
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Author : G. Trottet
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Particle Acceleration And Trapping In Solar Flares written by G. Trottet and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
These are the Proceedings of the Second CESRA Workshop on Particle Acceleration and Trapping in Solar Flares. The Workshop was held on June 23-26,1986, at the city hall of Aubigny-sur-Nere (France), near Bourges and near the Nan
Physical Processes In Solar Flares
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Author : B.V. Somov
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Physical Processes In Solar Flares written by B.V. Somov and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
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.
Solar Flares
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Author : Zdenek Svestka
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Solar Flares written by Zdenek Svestka and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
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.
Electron And Proton Kinetics And Dynamics In Flaring Atmospheres
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Author : Valentina Zharkova
language : en
Publisher: John Wiley & Sons
Release Date : 2012-06-25
Electron And Proton Kinetics And Dynamics In Flaring Atmospheres written by Valentina Zharkova and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-06-25 with Science categories.
This timely book presents new research results on high-energy particle physics related to solar flares, covering the theory and applications of the reconnection process in a clear and comprehensible way. It investigates particle kinetics and dynamics in flaring atmospheres and their diagnostics from spectral observations, while providing an analysis of the observation data and techniques and comparing various models. Written by an internationally acclaimed expert, this is vital reading for all solar, astro-, and plasma physicists working in the field.
Solar Flare Loops Observations And Interpretations
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Author : Guangli Huang
language : en
Publisher: Springer
Release Date : 2018-01-31
Solar Flare Loops Observations And Interpretations written by Guangli Huang and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-01-31 with Science categories.
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.