Search results for: the-internal-solar-angular-velocity

The Internal Solar Angular Velocity

Author : B.R. Durney
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It is clear that the discovery of solar eigenmodes and the resulting possibility of probing the solar interior is an event of primary importance for solar physics in general and for theories of the inner solar angular velocity in particular. While these theories are basic for the understanding of the solar spin down, differential rotation, dynamo and activity, they are however, extremely complex, and in all likelihood only limited further progress could have been achieved without the guidance of observations. Until recently and in spite of the scant observational basis the theoretical work has moved forward as the perusal of this book shows. There cannot be any doubt, however, that the present, rapidly expanding, worldwide observational program will lead ultimately to a vigorous theoretical development of the field. It appeared to the organizers that a meeting centered on theories of the inner solar angular velocity, comprising presentations of the main research areas by the involved scientists, would significantly foster this development since it would help to clarify the basic ideas of the subject. The meeting, held at the National Solar Observatory/Sacramento Peak, from August 11 to August 14, was the eighth in a series of summer symposia at Sacramento Peak. The unqualified success of the meeting could not have been possible without the unlim ited devotion of the staff at Sacramento Peak, Ray Smartt, Frank and Pat Hegwer, Ramona Elrod in particular.

The Internal Solar Angular Velocity

Author : Bernard Durney
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A Review of what Numerical Simulations Tell Us about the Internal Rotation of the Sun

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The simulated solar differential rotation from two independent numerical modeling efforts agree with each other and with present solar observations. The models solve the nonlinear, three-dimensional, time-dependent, anelastic equations of motion for thermal convection in a stratified, rotating, spherical shell. The simulated angular velocity in the convection zone is constant on cylinders coaxial with the rotation axis, maximum at the equator and decreasing with depth. The latitudinal variation of this angular velocity at the surface is in agreement with Doppler measurements of the solar surface rotation rate. The radial variation through the convection zone is consistent with the analysis of the rotational frequency splitting of solar oscillations. 15 refs., 5 figs.

The Solar Tachocline

Author : D. W. Hughes
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Helioseismology has enabled us to probe the internal structure and dynamics of the Sun, including how its rotation varies in the solar interior. The unexpected discovery of an abrupt transition - the tachocline - between the differentially rotating convection zone and the uniformly rotating radiative interior has generated considerable interest and raised many fundamental issues. This volume contains invited reviews from distinguished speakers at the first meeting devoted to the tachocline, held at the Isaac Newton Institute. It provides a comprehensive account of the understanding of the properties and dynamics of the tachocline, including both observational results and major theoretical issues, involving both hydrodynamic and magnetohydrodynamic behaviour. The Solar Tachocline is a valuable reference for researchers and graduate students in astrophysics, heliospheric physics and geophysics, and the dynamics of fluids and plasmas.

Literature 1987

Author : S. Böhme
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Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 43 records literature published in 1987 and received before August 15, 1987. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Beate Gobel, Ms. Monika Kohl, Ms. Sylvia Matyssek, Ms. Doris Schmitz-Braunstein, Ms. Utta-Barbara Stegemann. Mr. Jochen Heidt and Mr. Kristopher Polzine supported our task by careful proof reading. It is a pleasure to thank them all for their encouragement. Heidelberg, October 1987 The Editors Contents Introduction . . . . . . . . . . . 1 Concordance Relation: PHYS-AAA 3 Abbreviations 5 Periodicals, Proceedings, Books, Activities 001 Periodicals . . . . . . . . . . . 10 002 Bibliographical Publications, Documentation, Catalogues, Data Bases 50 003 Books ...... .

The Sun

Author : Michael Stix
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A wealth of new experimental and theoretical results has been obtained in solar physics since the first edition of this textbook appeared in 1989. Thus all nine chapters have been thoroughly revised, and about 100 pages and many new illustrations have been added to the text. The additions include element diffusion in the solar interior, the recent neutrino experiments, methods of image restoration, observational devices used for spectroscopy and polarimetry, and new developments in helioseismology and numerical simulation. The book takes particular advantage of the results of several recent space missions, which lead to substantial progress in our understanding of the Sun, from the deep interior to the corona and solar wind.

Flow and Creep in the Solar System Observations Modeling and Theory

Author : David B. Stone
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The NATO ASI held in the Geophysical Institute, University of Alaska Fairbanks, June 17-28, 1991 was, we believe, the first attempt to bring together geoscientists from all the disciplines related to the solar system where fluid flow is a fundamental phenomenon. The various aspects of flow discussed at the meeting ranged from the flow of ice in glaciers, through motion of the solar wind, to the effects of flow in the Earth's mantle as seen in surface phenomena. A major connecting theme is the role played by convection. For a previous attempt to review the various ways in which convection plays an important role in natural phenomena one must go back to an early comprehensive study by 1. Wasiutynski in "Astro physica Norvegica" vo1. 4, 1946. This work, little known now perhaps, was a pioneering study. In understanding the evolution of bodies of the solar system, from accretion to present-day processes, ranging from interplanetary plasma to fluid cores, the understanding of flow hydrodynamics is essentia1. From the large scale in planetary atmospheres to geological processes, such as those seen in magma chambers on the Earth, one is dealing with thermal or chemical convection. Count Rumford, the founder of the Royal Institution, studied thermal convection experimentally and realized its practical importance in domestic contexts.

Solar Interior and Atmosphere

Author : Arthur N. Cox
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Observational data derived from the world's largest solar telescopes are correlated with theoretical discussions in nuclear and atomic physics by contributors representing a wide range of interests in solar research.

Inside the Sun

Author : Gabrielle Berthomieu
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Proceedings of the 121st Colloquium of the International Astronomical Union, held at Versailles, France, May 22-26, 1989

Literature 1989

Author : Astronomisches Rechen-Institut
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From the reviews: "Astronomy and Astrophysics Abstracts has appeared in semi-annual volumes since 1969 and it has already become one of the fundemental 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 a 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 Review# "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#

Energy Research Abstracts

Author :
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Frontiers Of Astronomy In 1990 s Proceedings Of The Workshop

Author : Li Qi Bin
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The workshop on “Frontiers of Astronomy in 1990s” was held to commemorate the 70th anniversary of the founding of the Chinese Astronomical Society.In total this set of proceedings presents 12 invited papers and 15 contributions, covering the many fields and their development within the region. These include astronomy, astronomical instruments, high energy astrophysics and space astronomy, galaxies and large scale structure of the universe, stars, interstellar medium and the Galaxy, the Sun and the solar system and many more interesting topics in astronomy.15 distinguished scientists from 8 countries attended and presented their reports. These include Y Kozai, J Trümper, J P Swings, R E Williams, W Hillebrandt, F N Bash, W Wamsteker, M Créze, M Dennefeld, G Börner, Kaifu, H-Y Chiu, T C Weekes, J-S Shen and C-H Tsai.For those mystified by the stars, the planets and the universe as a whole, this volume promises to intrigue and transport you beyond the frontiers of astronomy.

Angular Momentum Evolution of Young Stars

Author : S Catalano
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This book reports the Proceedings of the NATO Advanced Research Workshop on "An gular Momentum Evolution of Young Stars" held from 17 to 21 September 1990 at Noto, Italy. The workshop had its immediate origin in a discussion about the availability of stel lar rotation data, that took place in 1987 at Viana do Castelo Portugal during the NATO meeting, Formation and Evolution of Low Mass Stars. We recognized that nearly 20 years had passed since the last meeting on stellar rotation and that significant progress in the observation of rotation rates in low mass stars had been made. During the last 20 years, new efficient instrumentation (CCD and photon counting de tectors and echelle spectrographs) and new analysis techniques (profile Fourier analysis) have allowed us to measure rotational velocities as low as 1-2 km/s and to reach low mass stars in young clusters. Even with these advances, rotational velocities of low mass stars would have remained challenging to determine if all single, low mass stars later than GO had rotational velocities of order or less than 10 km/sec. Evidence that this is not always the case was first provided by the photometric variability data obtained by van Leeuwen and Alphenaar for K dwarfs in the Pleiades and more recently by the vsini measurements of low mass stars in several young clusters.

Scientific and Technical Aerospace Reports

Author :
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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Energy Research Abstracts

Author :
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Accretion and Winds

Author : Gerhard Klare
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In order to bring the scientific events of the meetings of the Astronomische Gesellschaft (AG) to the attention of the worldwide astronomical community, an annual publication, Reviews in Modern Astronomy, was established. It is devoted exclusively to . the invited reviews, the Karl Schwarz schild lectures, and the high light contributions from leading scientists reporting on recent progress and scientific achievements at their respective institutes. This third volume continues the yearbook series of publications of the society. It comprises the complete set of contributions presented during the spring meeting of the AG at Berlin in March 1990, which was dedicated to the topic "Accretion and Winds". In addition four latecomers (two review and two highlight papers) delivered at the fall meeting at Graz, Austria in September 1989 close this volume. Heidelberg, September 1990 G: Klare Contents Some New Elements in Accretion Disk Theory By F. Meyer (With 5 Figures) . . . . . . . . . . . . . . . . . . . . . . . 1 Mass Transfer and Evolution in Close Binaries By A. R. King (With 4 Figures) . . . . . . . . . . . . . . . . . . . . . . . 14 Radiation Hydrodynamics of the Boundary Layer of Accretion Disks in Cataclysmic Variables By W. Kley (With 6 Figures) . . . . . . . . . . . . . . . . . . . . . . . . 21 Curious Observations of Cataclysmic Variables By F. V. Hessman (With 10 Figures) . . . . . . . . . . . . . . . . . . . 32 Accretion in AM Herculis Stars 44 By A. D. Schwope (With 12 Figures) X-ray Diagnostics of Accretion Disks By G. Hasinger (With 12 Figures) . . . . . . . . . . . . . . . . . . . . . 60 Accretion Phenomena at Neutron Stars By A. Rebetzky, H. Herold, U. Kraus, H. -P. Nollert, and H. Ruder (With 13 Figures) . . . . . . . . . . . . . . . . . . . . . .

Lectures on Solar and Planetary Dynamos

Author : M. R. E. Proctor
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Comprised of lectures for an intensive course held at the Newton Institute in Cambridge, as part of a NATO Advanced Study Institute, the topics covered within this volume include planetary and solar dynamos, fast dynamos, and the use of symmetry principles to derive evolution equations.

Solar Photosphere Structure Convection and Magnetic Fields

Author : Jan Olof Stenflo
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Solar and stellar photospheres constitute the layers most accessible to observations, forming the interface between the interior and the outside of the stars. The solar atmosphere is a rich physics laboratory, in which the whole spectrum of radiative, dynamical, and magnetic processes that tranfer energy into space can be observed. As the fundamental processes take place on very small spatial scales, we need high· resolution observations to explore them. On the other hand the small-scale processes act together to form global properties of the sun, which have their origins in the solar interior. The rapid advances in observational techniques and theoreticallllodelling over the past decade made it very timely to bring together scientists from east and west to the first lAU Symposium on this topic. The physics of the photosphere involves complicated interactions between magnetic fields, convection, waves, and radiation. During the past decade our understanding of these gener ally small-scale structures and processes has been dramatically advanced. New instrumen tations, on ground and in space, have given us new means to study the granular convection. Diagnostic methods in Stokes polarimetry have allowed us to go beyond the limitations of spatial resolution to explore the structure and dynamics of the subarcsec magnetic struc tures. Extensive numerical simulations of the interaction between convection and magnetic fields using powerful supercomputers are providing deepened physical insight. Granulation, magnetic fields, and dynamo processes are being explored in the photospheres of other stars, guided by our improved understanding of the solar photosphere.

The Cosmic Dynamo

Author : F. Krause
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Proceedings of the 157th Symposium of the International Astronomical Union held in Potsdam, Germany, September 7--11, 1992

Stellar Rotation

Author : Jean-Louis Tassoul
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Like the Earth and planets, stars rotate. Understanding how stars rotate is central to modelling their structure, formation and evolution, and how they interact with their environment and companion stars. This authoritative volume, first published in 2000, provides a lucid introduction to stellar rotation and the definitive reference to the subject. It combines theory and observation in a comprehensive survey of how the rotation of stars affects the structure and evolution of the Sun, single stars and close binaries. This book will be of primary interest to graduate students and researchers studying solar and stellar rotation and close binary systems. It will also appeal to those with a more general interest in solar and stellar physics, star formation, binary stars and the hydrodynamics of rotating fluids - including geophysicists, planetary scientists and plasma physicists.