Download or read book Numerical Simulations of Radiation and Heating from Non thermal Electrons in Solar Flares written by Jennifer A. Pollock and published by . This book was released on 2008 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Thermal nonthermal Approach to Solar Flares written by Stephen G. Benka and published by . This book was released on 1991 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Thermal Nonthermal Approach to Solar Flares written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: An approach for modeling solar flare high-energy emissions is developed in which both thermal and nonthermal particles coexist and contribute to the radiation. The thermal/nonthermal distribution function is interpreted physically by postulating the existence of DC sheets in the flare region. The currents then provide both primary plasma heating through Joule dissipation, and runaway electron acceleration. The physics of runaway acceleration is discussed. Several methods are presented for obtaining approximations to the thermal/nonthermal distribution function, both within the current sheets and outside of them. Theoretical hard x ray spectra are calculated, allowing for thermal bremsstrahlung from the heated plasma electrons impinging on the chromosphere. A simple model for hard x ray images of two-ribbon flares is presented. Theoretical microwave gyrosynchrotron spectra are calculated and analyzed, uncovering important new effects caused by the interplay of thermal and nonthermal particles. The theoretical spectra are compared with observed high resolution spectra of solar flares, and excellent agreement is found, in both hard x rays and microwaves. The future detailed application of this approach to solar flares is discussed, as are possible refinements to this theory. Benka, Stephen G. Goddard Space Flight Center CURRENT SHEETS; ELECTRON ACCELERATION; NONTHERMAL RADIATION; PLASMA HEATING; SOLAR FLARES; SOLAR RADIATION; SOLAR SPECTRA; SPACE PLASMAS; THERMAL RADIATION; BREMSSTRAHLUNG; CHROMOSPHERE; DISSIPATION; IMPINGEMENT; MICROWAVE SPECTRA; MICROWAVES; PLASMA CURRENTS; X RAY SPECTRA; X RAYS...
Download or read book Combined Modeling of Acceleration Transport and Hydrodynamic Response in Solar Flares 1 The Numerical Model written by and published by . This book was released on 2009 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acceleration and transport of high-energy particles and fluid dynamics of atmospheric plasma are interrelated aspects of solar flares, but for convenience and simplicity they were artificially separated in the past. We present here self consistently combined Fokker-Planck modeling of particles and hydrodynamic simulation of flare plasma. Energetic electrons are modeled with the Stanford unified code of acceleration, transport, and radiation, while plasma is modeled with the Naval Research Laboratory flux tube code. We calculated the collisional heating rate directly from the particle transport code, which is more accurate than those in previous studies based on approximate analytical solutions. We repeated the simulation of Mariska et al. with an injection of power law, downward-beamed electrons using the new heating rate. For this case, a -10% difference was found from their old result. We also used a more realistic spectrum of injected electrons provided by the stochastic acceleration model, which has a smooth transition from a quasi-thermal background at low energies to a non thermal tail at high energies. The inclusion of low-energy electrons results in relatively more heating in the corona (versus chromosphere) and thus a larger downward heat conduction flux. The interplay of electron heating, conduction, and radiative loss leads to stronger chromospheric evaporation than obtained in previous studies, which had a deficit in low-energy electrons due to an arbitrarily assumed low-energy cutoff. The energy and spatial distributions of energetic electrons and bremsstrahlung photons bear signatures of the changing density distribution caused by chromospheric evaporation. In particular, the density jump at the evaporation front gives rise to enhanced emission, which, in principle, can be imaged by X-ray telescopes. This model can be applied to investigate a variety of high-energy processes in solar, space, and astrophysical plasmas.
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 Recent Advances in the Understanding of Solar Flares written by S.R. Kane and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: These Proceedings result from the papers and discussions of the U.S.-Japan Seminar "Recent Advances in the Understanding of Solar Flares" held in Tokyo October 5-8, 1982. The meeting was sponsored jointly by the Japan Society for the Promotion of Science and the u.S. National Science Foundation. The principal aim of the meeting was to obtain the most up-to-date physical picture of solar flares by bringing together results from the recent observations by the Solar Maximum Mission (SMM) and HINOTORI satellites, together with other satellite data and ground-based data at both optical and radio wavelengths. These data cover the recent maximum of the solar activity cycle. The SMM and HINOTORI introduced a new dimension in flare observations by carrying out the first hard X-ray imaging observations, and the organizers especially felt that an intense discussion of the significance of these results in the context of flare theories would be important. Starting with an introductory presentation of the characteristics of the instruments on board the satellites, the sessions of the first day and the beginning of the second dealt mainly with energy transport in flares and with .the formation process of the hot plasma which is .
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 A Theoretical Investigation of Optical Emission in Solar Flares written by William Paul Abbett and published by . This book was released on 1998 with total page 286 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Energetics and Dynamics of Simple Impulsive Solar Flares written by and published by . This book was released on 1987 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Simplified Method for Computing Radiative Energy Loss Due to Spectral Lines written by Richard C. Canfield and published by . This book was released on 1974 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The paper lists Fortran-IV programs that implement a simplified method for computing radiative loss rates due to spectral lines. As it is planned to apply these techniques to solar flare models, the programs are set up to take into account Lyman alpha, Balmer-alpha and H-, the principal contributors to radiative energy loss in solar flares.
Download or read book Energetics and Dynamics of Simple Impulsive Solar Flares written by R. Starr and published by . This book was released on 1987 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 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 Radiative Processes in Astrophysics written by George B. Rybicki and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiative Processes in Astrophysics: This clear, straightforward, and fundamental introduction is designed to present-from a physicist's point of view-radiation processes and their applications to astrophysical phenomena and space science. It covers such topics as radiative transfer theory, relativistic covariance and kinematics, bremsstrahlung radiation, synchrotron radiation, Compton scattering, some plasma effects, and radiative transitions in atoms. Discussion begins with first principles, physically motivating and deriving all results rather than merely presenting finished formulae. However, a reasonably good physics background (introductory quantum mechanics, intermediate electromagnetic theory, special relativity, and some statistical mechanics) is required. Much of this prerequisite material is provided by brief reviews, making the book a self-contained reference for workers in the field as well as the ideal text for senior or first-year graduate students of astronomy, astrophysics, and related physics courses. Radiative Processes in Astrophysics also contains about 75 problems, with solutions, illustrating applications of the material and methods for calculating results. This important and integral section emphasizes physical intuition by presenting important results that are used throughout the main text; it is here that most of the practical astrophysical applications become apparent.
Download or read book Solar Flares and Collisions between Current Carrying Loops written by Jun-Ichi Sakai and published by Springer. This book was released on 1996-08-31 with total page 0 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.
