Download or read book Rapid Magnetic Energy Release Its Possible Role in Coronal Heating and Solar Wind Acceleration written by George L. Withbroe and published by . This book was released on 1983 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies of the EUV emission from coronal bright points, active regions and apicules suggest taht stochastic mechanisms may plan an important role in heating the solar atmosphere at chromospheric and coronal levels. In small magnetic bipolar regions (spatial extent 1') the observed EUV variations suggest that impulsive heating at chromospheric and coronal levels appears to be very important, possibly the dominant form of heating. The mechanism most likely involves rapid release of magnetic energy, possibly associated with the emergence of magnetic flux from lower levels into the chromosphere and corona. In larger scale ( 1') magnetic bipolar regions, there is evidence for both quasi-steady and impulsive heating, with quasi-steady heating dominating. This heating could be caused by either a mechanism such as steady-state current dissipation, or by a stochastic process whose integrated effect (resulting from the smoothing caused by finite radiative and conductive cooling times) yields a nearly constant radiative output. The widespread variability of the emission in spectral lines formed at transition region temperatures (100000

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1993 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 1344 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Solar and Space Physics written by National Research Council and published by National Academies Press. This book was released on 2014-09-25 with total page 37 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 2010, NASA and the National Science Foundation asked the National Research Council to assemble a committee of experts to develop an integrated national strategy that would guide agency investments in solar and space physics for the years 2013-2022. That strategy, the result of nearly 2 years of effort by the survey committee, which worked with more than 100 scientists and engineers on eight supporting study panels, is presented in the 2013 publication, Solar and Space Physics: A Science for a Technological Society. This booklet, designed to be accessible to a broader audience of policymakers and the interested public, summarizes the content of that report.

Download or read book Physics of the Solar Corona written by Constantin J. Macris and published by . This book was released on 1971 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Magnetic Influences on the Solar Wind written by Lauren Woolsey and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The steady, supersonic outflow from the Sun we call the solar wind was first posited in the 1950s and initial theories rightly linked the acceleration of the wind to the existence of the million-degree solar corona. Still today, the wind acceleration mechanisms and the coronal heating processes remain unsolved challenges in solar physics. In this work, I seek to answer a portion of the mystery by focusing on a particular acceleration process: Alfven waves launched by the motion of magnetic field footpoints in the photosphere. The entire corona is threaded with magnetic loops and flux tubes that open up into the heliosphere. I have sought a better understanding of the role these magnetic fields play in determining solar wind properties in open flux tubes. After an introduction of relevant material, I discuss my parameter study of magnetic field profiles and the statistical understanding we can draw from the resulting steady-state wind. In the chapter following, I describe how I extended this work to consider time dependence in the turbulent heating by Alfven waves in three dimensional simulations. The bursty nature of this heating led to a natural next step that expands my work to include not only the theoretical, but also a project to analyze observations of small network jets in the chromosphere and transition region, and the underlying photospheric magnetic field that forms thresholds in jet production. In summary, this work takes a broad look at the extent to which Alfven-wave-driven turbulent heating can explain measured solar wind properties and other observed phenomena.

Download or read book Exploring the Solar Wind written by Marian Lazar and published by BoD – Books on Demand. This book was released on 2012-03-21 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book consists of a selection of original papers of the leading scientists in the fields of Space and Planetary Physics, Solar and Space Plasma Physics with important contributions to the theory, modeling and experimental techniques of the solar wind exploration. Its purpose is to provide the means for interested readers to become familiar with the current knowledge of the solar wind formation and elemental composition, the interplanetary dynamical evolution and acceleration of the charged plasma particles, and the guiding magnetic field that connects to the magnetospheric field lines and adjusts the effects of the solar wind on Earth. I am convinced that most of the research scientists actively working in these fields will find in this book many new and interesting ideas.

Download or read book Fast Solar Wind Driven by Parametric Decay Instability and Alfv n Wave Turbulence written by Munehito Shoda and published by Springer Nature. This book was released on 2021-04-13 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses key theoretical aspects concerning the formation of the solar wind: the most essential building block in the heliosphere, in which planets orbit. To understand the influence of solar activity on planetary magnetospheres and atmospheres, we need to first understand the origin of the solar wind, which is still under debate. This book presents the outcomes of state-of-the-art numerical simulations of solar wind acceleration, including the first three-dimensional simulation of the turbulence-driven solar wind model. One of the book’s goals is to include compressional effects in the dynamics of solar wind turbulence; accordingly, it discusses parametric decay instability in detail. Several key aspects that are relevant to the Parker Solar Probe observations are also discussed. Given its scope, the book plays a key role in bridging the gap between the theory of magnetohydrodynamic turbulence and current/future in-situ observations of the solar wind. This book is based on the Ph.D. thesis by the author, which won the 2019 International Astronomical Union Division E Ph.D. prize.

Download or read book The Evolution of Modeled Coronal Mass Ejection in the Lower Corona written by Rebekah Minnel Evans Frolov and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coronal mass ejections (CMEs) and their associated shocks are major sources of space weather. In order to forecast their impact at Earth, it is crucial to accurately model their propagation in interplanetary space. The only tool capable of treating the large scales of CME evolution is global magnetohydrodynamics (MHD) modeling. However, this approach cannot resolve the small scales on which important processes occur (such as the acceleration of the solar wind and coronal heating). The solar wind solution depends on which method is utilized to mimic these processes. And because the evolution of a CME depends crucially on its interaction with the solar wind, the CME evolution will also be connected to the heating mechanisms and drivers utilized in an MHD model. In the first part of the thesis, we show that the ad hoc approaches to coronal heating used in global MHD models leads to unphysical conditions for CME-driven shock formation in the lower corona (1-10 solar radii). We present this argument in two steps. First, we present a CME simulation in which the solar wind was accelerated and heated by reducing the value of the polytropic index (to less than the adiabatic value) in the lower corona. As it is not well understood, we do not model the CME initiation process - we utilize an out-of-equilibrium Titov-Demoulin flux rope to begin the eruption. We analyze several aspects of the CME, such as its kinematics and energy evolution, the shock formation and evolution, the plasma flows in the CME-sheath and their connection to the CME magnetic field vector, and the plasma pile-up at the front of the CME. We find that some characteristics are inconsistent with the observed properties of CMEs, and we connect these to the ad hoc treatment of the solar wind heating. Second, we use data of CME shock-accelerated solar energetic particle events to constrain the profile of the Alfven speed in the lower corona. We show that the Alfven speed profile from global MHD models with ad hoc heating is not aligned with these observations, but that local (one dimensional) models with physically-motivated Alfven wave dissipation as a heating mechanism were in agreement. In the second part of the thesis, we study the resonant absorption of surface Alfven waves (SAW), a process which heats the solar wind. It is driven by a transverse gradient in the local Alfven speed (in relation to the magnetic field direction). In the solar corona, we expect this mechanism to occur at the boundaries of open and closed magnetic fields. We make the first estimation of SAW energy dissipation in the solar corona and find that it is comparable to the ad hoc heating a polytropic model at the boundary of open and closed magnetic fields and in subpolar open field regions. Next, we implemented the SAW damping mechanism into the new solar corona component of the Space Weather Modeling Framework, in which Alfven wave energy transport is self-consistently coupled to the MHD equations. The model already included wave dissipation along open magnetic field lines, mimicking turbulence. We demonstrate that including SAW dissipation in the model improved agreement with observations of coronal temperature both near the Sun and in the inner heliosphere by comparing with data from Ulysses and the Solar Terrestrial Relations Observatory (STEREO). Also, the inclusion of SAW dissipation steepened the Alfven speed profile in the lower corona, aligning the Alfven profile better with observational constraints of shock formation. In the final part of the thesis, we modeled a CME in this newly developed solar wind background, and studied the interaction between the CME and the wind. We generate the eruption with a flux rope. We constrain the parameters of the flux rope with data from the 13 May 2005 eruption, including H-alpha images of the pre-eruption magnetic field, coronagraph images of the CME's shape and velocity. Because the flux rope traveled faster than the local magnetosonic speed, it acted as a piston and drove a shock wave ahead of it. The CME-driven shock had a strong impact on the solar wind environment through which it propagates: it altered the wave energy by concentrating it in the sheath through advection, and also increasing its value through momentum transfer. This simulation demonstrated how Alfven waves are focused into the sheaths of ICMEs. The wave energy is then dissipated at the shock due to SAW damping. The shock heating accounted for 10% of the total change in thermal energy of the CME. The resulting temperature distribution of the CME is more aligned with observations than from a CME modeled in a polytropic solar wind. This thesis has improved our understanding of the interaction between a CME and the solar wind through which it propagates. Our picture of CME-evolution in the lower corona will be tested by future missions Solar Probe (which will sample this region directly) and the Solar Orbiter.

Download or read book Lectures on Solar Physics written by H.M. Antia and published by Springer. This book was released on 2008-01-11 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume has grown out of lectures addressing primarily graduate students and researchers working in related areas in both astrophysics and space sciences. All contributions are self-contained and do not require prior in-depth knowledge of solar physics. The result is a unique textbook that fulfills the needs of those wishing to have a pedagogic exposition of solar physics bringing them up-to-date in a field full of vitality and with exciting research.

Download or read book Solar Astrophysics written by Peter V. Foukal and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This revised edition of Solar Astrophysics describes our current understanding of the sun - from its deepest interior, via the layers of the directly observable atmosphere to the solar wind, right out to its farthest extension into interstellar space. It includes a comprehensive account of the history of solar astrophysics, along with an overview of the key instruments throughout the various periods. In contrast to other books on this topic, the choice of material deals evenhandedly with the entire scope of important topics covered in solar research. The authors make the advances in our understanding of the sun accessible to students and non-specialists by way of careful use of relatively simple physical concepts. The book offers an incisive, reliable, and well-planned look at all that is fascinating and new in studies of the sun.

Download or read book Coronal Holes and Solar Wind Acceleration written by John L. Kohl and published by Springer Science & Business Media. This book was released on 2013-11-09 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: The SOHO-7 Workshop was held from 28 September through 1 October 1998 at the Asticou Inn in Northeast Harbor, Maine. The primary topic of this Workshop was the impact of SOHO observations on our understanding of the nature and evolution of coronal holes and the acceleration and composition of the solar wind. The presentations and discussions occasionally went beyond this topic to include the impact of the reported research on other solar structures and the heliosphere. SOHO (the Solar and Heliospheric Observatory), a project of international cooperation between ESA and NASA, was launched in December 1995 and began its science operations during the first few months of 1996. To many solar and space physicists, it was a great advantage that SOHO began itscomprehensive look at the Sun during the 1996 solar minimum. The qualitatively simple two-phase corona, with polar coronal holes expanding into the high-speed solar wind, and a steady equatorial streamer belt related somehow to the stochastic slow-speed solar wind, allowed various SOHO diagnostics to be initiated with a reasonably well understoodcircumsolar geometry. The analysis of subsequentSOHO measurements made during the rising phase of solar cycle 23 will continue to benefit from what has been learned from the first two years of data.

Download or read book Astronomy and Astrophysics Abstracts written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-14 with total page 1180 pages. Available in PDF, EPUB and Kindle. Book excerpt: From the reviews: Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundamental publications in the fields of astronomy, astrophysics and neighbouring sciences. It is the most important English-language abstracting journal in the mentioned branches. ... The abstracts are classified under more than hundred subject categories, thus permitting a quick survey of the whole extended material. The AAA is a valuable and important publication for all students and scientists working in the fields of astronomy and related sciences. As such it represents a necessary ingredient of any astronomical library all over the world." Space Science Reviews #1 "Dividing the whole field plus related subjects into 108 categories, each work is numbered and most are accompanied by brief abstracts. Fairly comprehensive cross-referencing links relevant papers to more than one category, and exhaustive author and subject indices are to be found at the back, making the catalogues easy to use. The series appears to be so complete in its coverage and always less than a year out of date that I shall certainly have to make a little more space on those shelves for future volumes." The Observatory Magazine #1

Download or read book The Problem of Coronal Heating written by Philip Judge and published by Springer Nature. This book was released on with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics of the Solar Corona written by Markus Aschwanden and published by Springer Science & Business Media. This book was released on 2006-01-30 with total page 946 pages. Available in PDF, EPUB and Kindle. Book excerpt: A thorough introduction to solar physics based on recent spacecraft observations. The author introduces the solar corona and sets it in the context of basic plasma physics before moving on to discuss plasma instabilities and plasma heating processes. The latest results on coronal heating and radiation are presented. Spectacular phenomena such as solar flares and coronal mass ejections are described in detail, together with their potential effects on the Earth.

Download or read book Literature 1980 Part 1 written by Siegfried Böhme and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 949 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts, which has appeared in semi-annual volumes since 1969, is de voted to the recording, summarizing and indexing of astronomical publications throughout the world. It is prepared under the auspices of the International Astronomical Union (according to a resolution adopted at the 14th General Assembly in 1970). Astronomy and Astrophysics Abstracts aims to present a comprehensive documentation of literature in all fields of astronomy and astrophysics. Every effort will be made to ensure that the average time interval between the date of receipt of the original literature and publication of the abstracts will not exceed eight months: This time interval is near to that achieved by monthly abstracting journals, com pared to which our system of accumulating abstracts for about six months offers the advantage of greater convenience for the user. I, 1980; some older Volume 27 contains literature published in 1980 and received before August literature which was received late and which is not recorded in earlier volumes is also included. We acknowledge with thanks contributions to this volume by Dr. J. Bouska, Prague, who surveyed journals and publications in Czech and supplied us with abstracts in English.

Download or read book Coronal Magnetometry written by Sarah E. Gibson and published by Frontiers Media SA. This book was released on 2017-07-11 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetism defines the complex and dynamic solar corona. It determines the magnetic loop structure that dominates images of the corona, and stores the energy necessary to drive coronal eruptive phenomena and flare explosions. At great heights the corona transitions into the ever-outflowing solar wind, whose speed and three-dimensional morphology are controlled by the global coronal magnetic field. Coronal magnetism is thus at the heart of any understanding of the nature of the corona, and essential for predictive capability of how the Sun affects the Earth. Coronal magnetometry is a subject that requires a concerted effort to draw together the different strands of research happening around the world. Each method provides some information about the field, but none of them can be used to determine the full 3D field structure in the full volume of the corona. Thus, we need to combine them to understand the full picture. The purpose of this Frontiers Research Topic on Coronal Magnetometry is to provide a forum for comparing and coordinating these research methods, and for discussing future opportunities.