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Author: A. J. Hundhausen
Publisher: Springer Science & Business Media
ISBN: 3642654142
Category : Science
Languages : en
Pages : 250
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Book Description
Little more than ten years have passed since spaceprobe-borne instruments con clusively demonstrated the existence of the solar wind. These observations con firmed the basic validity of a theoretical model, first proposed by E. N. Parker, predicting a continuous, rapid expansion of the solar corona. The subsequent decade has seen a tremendous growth in both the breadth and sophistication of solar wind observations; the properties of the interplanetary plasma near the orbit of the earth are now known in great detail. The theory of the coronal ex pansion has also been highly refilled both in the sense of including additional physical processes, and of treating more realistic (time-dependent and non spheri cally-symmetric) coronal boundary conditions. The present volume is an attempt to synthesize the solar wind observations and coronal expansion models from this decade of rapid development. The ultimate goal is, of course, the interpretation of observed solar wind phenomena as the effects of basic physical processes occurring in the coronal and interplanetary plasma and as the natural manifestations of solar properties and structures. This approach implies an emphasis upon the "large-scale" features revealed by the observations. It requires extensive use of the concepts and methods of fluid mechanics.
Author: A. J. Hundhausen
Publisher: Springer Science & Business Media
ISBN: 3642654142
Category : Science
Languages : en
Pages : 250
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Book Description
Little more than ten years have passed since spaceprobe-borne instruments con clusively demonstrated the existence of the solar wind. These observations con firmed the basic validity of a theoretical model, first proposed by E. N. Parker, predicting a continuous, rapid expansion of the solar corona. The subsequent decade has seen a tremendous growth in both the breadth and sophistication of solar wind observations; the properties of the interplanetary plasma near the orbit of the earth are now known in great detail. The theory of the coronal ex pansion has also been highly refilled both in the sense of including additional physical processes, and of treating more realistic (time-dependent and non spheri cally-symmetric) coronal boundary conditions. The present volume is an attempt to synthesize the solar wind observations and coronal expansion models from this decade of rapid development. The ultimate goal is, of course, the interpretation of observed solar wind phenomena as the effects of basic physical processes occurring in the coronal and interplanetary plasma and as the natural manifestations of solar properties and structures. This approach implies an emphasis upon the "large-scale" features revealed by the observations. It requires extensive use of the concepts and methods of fluid mechanics.
Author: John L. Kohl
Publisher: Springer Science & Business Media
ISBN: 9401591679
Category : Science
Languages : en
Pages : 360
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Book Description
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.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721236251
Category :
Languages : en
Pages : 26
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Book Description
The solar wind not only forms the space environment of Earth and other planets, but is also the cause of many phenomena observed in the Earth's atmosphere, such as aurorae. The expansion of the coronal plasma of the Sun is characteristic to many main sequence stars, and thus provides an example for understanding stellar winds as well. In spite of its importance for both space science and stellar physics, basic solar wind properties remain essentially unresolved. Since its discovery about 50 years ago, the complexity of the Sun corona - solar wind system has complicated the interpretation of observations. Recent progress in remote sensing observations as provided for example by YOHKOH, SOHO, SPARTAN and ULYSSES as well as some ground based techniques such as Interplanetary Scintillation observations, offer a compelling opportunity to unravel the 50 year old puzzle regarding the heat source or sources that cause the expansion of the solar corona. The new era of solar wind observations initiated by SOHO and ULYSSES, have also led to a wealth of new theoretical approaches. The goal of the proposed research was to carry out an integrated study of the coronal and solar wind plasma making use of the opportunities provided by the above spacecraft, as well as plasma emission calculations and new ideas on solar wind expansion theory. Esser, Ruth and Wagner, William J. (Technical Monitor) Goddard Space Flight Center
Author: J. R. Herring
Publisher:
ISBN:
Category : Solar wind
Languages : en
Pages : 24
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Book Description
"Parker's model of a spherically expanding corona, the "solar wind," is compared with D.E. Blackwell's observations of the 1954 minimum equatorial corona. A significant discrepancy is found between the predicted and the observed electron densities at distances from the sun greater than 20 solar radii. Blackwell's data are found to be consistent with a model in which the corona expands mostly within a disk less than 25 solar radii thick, lying within the sun's equatorial plane. The thickness of the disk as a function of distance from the sun is qualitatively explained in terms of magnetic pressure. The solar wind is found to have a considerable effect on the lunar atmosphere. First, the calculated density of the lunar atmosphere is greatly reduced by collisions with protons in the solar wind. If the flux of particles in this wind has the conventional values ranging between 10(exp 10) to 10(exp 11) per sq cm-sec, the calculations yield a lunar pressure of 10(exp -13) atmosphere of argon, in agreement with the value predicted by Elsmore and Whitfield on the basis of observations on the occultation of radio stars. Second, following a suggestion by Gold, it was found that the collisions of solar-wind protons with the lunar surface produce an atmosphere of cold neutral hydrogen with a density of 10(exp 5) per cu cm at the lunar surface. The density falls off at greater distances in accordance with the inverse-square law. Estimates indicate that the interaction of solar particles with the neutral hydrogen will produce an extended lunar ionosphere with a density of the order of 400 protons/cu cm in the vicinity of the moon."
Author: Constantin J. Macris
Publisher:
ISBN:
Category : Sun
Languages : en
Pages : 0
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Book Description
Author: Rainer Schwenn
Publisher: Springer Science & Business Media
ISBN: 3642753647
Category : Science
Languages : en
Pages : 360
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Book Description
Physics of the Inner Heliosphere gives for the first time a comprehensive and complete summary of our knowledge of the inner solar system. Using data collected over more than 11 years by the HELIOS twin solar probes, one of the most successful ventures in unmanned space exploration, the authors have compiled six extensive reviews of the physical processes of the inner heliosphere and their relation to the solar atmosphere. Researchers and advanced students in space and plasma physics, astronomy, and solar physics will be surprised to see just how closely the heliosphere is tied to, and how sensitively it depends on, the sun. Volume 2 deals with particles, waves, and turbulence, with chapters on: - magnetic clouds - interplanetary clouds - the solar wind plasma and MHD turbulence - waves and instabilities - energetic particles in the inner solar system
Author: John M. Wilcox
Publisher:
ISBN:
Category :
Languages : en
Pages : 29
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Book Description
In the last few years it was learned that the solar corona and the solar wind are three-dimensional. That is, the deviations from spherical or even cylindrical symmetry and first-order effects, that are important for our basic description and indeed physical understanding of the coronal expansion. The recognition of this simple fact has been a slow process; perhaps because it complicates the mathematical treatment. Even a quick look at the solar corona reveals a highly structured medium with large density gradients. It has long- almost for a century as a matter of fact (Bigelow, 1889)- been suggested that magnetic fields are the fundamental agent that controls the shape of the corona and determines the inner boundary conditions for the solar wind escape. Only recently have we recognized how dominant is the role of large-scale magnetic fields in determining the global structure of the solar wind. The highly successful 'SKYLAB Workshop on Coronal Holes' that was conducted last year has been important for the general acceptance of the new three-dimensional description of the structure of the corona and the interplanetary magnetic field. Zirker (1977) and Hundhausen (1977) have aptly summarized the insight resulting from this work. The present review will attempt a further synthesis based on a broader database than that available to the Workshop. We will attempt to provide a unified viewpoint recognizing that such an attempt is usually associated with a certain degree of oversimplification.
Author: Leon Golub
Publisher: Cambridge University Press
ISBN: 052188201X
Category : Science
Languages : en
Pages : 405
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Book Description
Second edition graduate level textbook giving an up-to-date treatment of our understanding of the solar corona.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
It is suggested that corpuscular radiation is hydrodynamic expansion of the solar corona which is called solar wind. Arguments are presented for this expansion of the solar corona in terms of motion of the comet tail aurorae production, magnetic storms, and cosmic-ray effects on earth. The corona is taken to be isotherrnal out to an undefined distance (in multiples of the radius of the base of the corona) and from there it expands adiabatically until supersonic velocities are reached at infinity. The solar wind is considered to continue after five astronomical units on the spiralling solar magnetic field. Applications of the solar wind hypothesis to solar sailing are discussed. (C.J.G.).
Author: Henny J. G. L. M. Lamers
Publisher: Cambridge University Press
ISBN: 9780521595650
Category : Nature
Languages : en
Pages : 456
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Book Description
The first comprehensive introduction to the observations and theories of stellar winds; a long-awaited graduate textbook, written by two founders of the field.
