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Author: L.A. Willson
Publisher: Springer Science & Business Media
ISBN: 9400921055
Category : Science
Languages : en
Pages : 366
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Book Description
Fundamental unsolved problems of stellar astrophysics include the effects of angular momentum on stellar structure and evolution, the nature and efficiency of the processes by which angular momentum is redistributed within and lost from stars, and the role that stellar rotation plays in enhancing or driving stellar mass loss. There appears to be a qualitative change in the nature and efficiency of these mechanisms near spectral type FO: hotter (more massive) stars typically retain more angular momentum at least until they reach the main sequence, while cooler stars typically spin down quickly. For the hotter stars, recent work suggests a strong link between the type of pulsation behavior, the mass loss rates, and the rotation velocity. If the same mechanisms are able to drive mass loss from the main sequence A stars, as has recently been proposed, then the current interpretations of a number of observations will be drastically affected: e. g. the ages of clusters may be incorrect by up to a factor of two, and the surface abundances of isotopes of He, Li and Be may no longer give constraints on cosmological nucleosynthesis. There are also effects on the evolution of the abundances of elements in the interstellar medium and on the general evolution of populations of stars. Thus the questions of the mechanisms of angular momentum and mass loss of stars more massive than the sun is important not only for stellar studies but for the foundations of much of modern astrophysics.
Author: L.A. Willson
Publisher: Springer Science & Business Media
ISBN: 9400921055
Category : Science
Languages : en
Pages : 366
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Book Description
Fundamental unsolved problems of stellar astrophysics include the effects of angular momentum on stellar structure and evolution, the nature and efficiency of the processes by which angular momentum is redistributed within and lost from stars, and the role that stellar rotation plays in enhancing or driving stellar mass loss. There appears to be a qualitative change in the nature and efficiency of these mechanisms near spectral type FO: hotter (more massive) stars typically retain more angular momentum at least until they reach the main sequence, while cooler stars typically spin down quickly. For the hotter stars, recent work suggests a strong link between the type of pulsation behavior, the mass loss rates, and the rotation velocity. If the same mechanisms are able to drive mass loss from the main sequence A stars, as has recently been proposed, then the current interpretations of a number of observations will be drastically affected: e. g. the ages of clusters may be incorrect by up to a factor of two, and the surface abundances of isotopes of He, Li and Be may no longer give constraints on cosmological nucleosynthesis. There are also effects on the evolution of the abundances of elements in the interstellar medium and on the general evolution of populations of stars. Thus the questions of the mechanisms of angular momentum and mass loss of stars more massive than the sun is important not only for stellar studies but for the foundations of much of modern astrophysics.
Author: Wolf-Rainer Hamann
Publisher: Universitätsverlag Potsdam
ISBN: 3940793337
Category : Stellar winds
Languages : en
Pages : 262
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Book Description
Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
ISBN: 9780521889902
Category : Science
Languages : en
Pages : 716
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Book Description
IAU Symposium 259 presents the first interdisciplinary, comprehensive review of the role of cosmic magnetic fields, involving astronomers and physicists from across the community. Offering both theoretical and observational topics ranging from Earth's habitability to the origin of the universe, this is an invaluable summary for researchers and graduate students.
Author: Andre Maeder
Publisher: Springer Science & Business Media
ISBN: 3540769498
Category : Science
Languages : en
Pages : 832
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Book Description
Rotation is ubiquitous at each step of stellar evolution, from star formation to the final stages, and it affects the course of evolution, the timescales and nucleosynthesis. Stellar rotation is also an essential prerequisite for the occurrence of Gamma-Ray Bursts. In this book the author thoroughly examines the basic mechanical and thermal effects of rotation, their influence on mass loss by stellar winds, the effects of differential rotation and its associated instabilities, the relation with magnetic fields and the evolution of the internal and surface rotation. Further, he discusses the numerous observational signatures of rotational effects obtained from spectroscopy and interferometric observations, as well as from chemical abundance determinations, helioseismology and asteroseismology, etc. On an introductory level, this book presents in a didactical way the basic concepts of stellar structure and evolution in "track 1" chapters. The other more specialized chapters form an advanced course on the graduate level and will further serve as a valuable reference work for professional astrophysicists.
Author: International Astronomical Union. Symposium
Publisher: Cambridge University Press
ISBN: 9780521889834
Category : Science
Languages : en
Pages : 506
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Book Description
Stellar models are the very basic building blocks with which we build up our knowledge of the Universe. New numerical experiments are heralding a new level of sophistication in our ability to model, and understand, how stars work. This volume provides an overview and the most recent advances in modeling of stellar structure and evolution. Modeling of stars relies on our understanding of the detailed physical processes happening in stars, and the most recent observations of stars made by modern large telescopes and current high technologies. IAU Symposium 252 presents the most recent developments in five key areas, including: improvements of the physical ingredients of stellar models; the evolution of low and intermediate mass stars; the evolution of massive stars; close binary evolution; and stellar physics in the era of very large telescopes. This overview of stellar research is at a level suitable for research astronomers and graduate students.
Author: Jorge Sahade
Publisher: Elsevier
ISBN: 1483157792
Category : Science
Languages : en
Pages : 199
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Book Description
Interacting Binary Stars deals with the development, ideas, and problems in the study of interacting binary stars. The book consolidates the information that is scattered over many publications and papers and gives an account of important discoveries with relevant historical background. Chapters are devoted to the presentation and discussion of the different facets of the field, such as historical account of the development in the field of study of binary stars; the Roche equipotential surfaces; methods and techniques in space astronomy; and enumeration of binary star systems that are studied meticulously by scientists. Astronomers, astrophysicists, physicists, researchers, and students in related fields will find the book interesting.
Author: Peter V. Foukal
Publisher: John Wiley & Sons
ISBN: 3527618082
Category : Science
Languages : en
Pages : 480
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Book Description
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.
Author: Jean-Pierre Rozelot
Publisher: Springer Science & Business Media
ISBN: 3540878300
Category : Science
Languages : en
Pages : 266
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Book Description
The Sun and stars rotate in di?erent ways and at di?erent velocity rates. The knowledge of how they rotate is important in understanding the formation and evolution of stars and their structure. The closest star to our Earth, the Sun, is a good laboratory to study in detail the rotation of a G star and allows to test new ideas and develop new techniques to study stellar rotation. More or less massive, more or lessevolved objects, however, can have averydi?erent rotation rate, structure and history. In recent years our understanding of the rotation of the Sun has greatly improved. The Sun has a well-known large-scale rotation, which can be m- sured thanks to visible features across the solar disk, such as sunspots, or via spectroscopy. In addition, several studies cast light on di?erential rotation in the convective zone and on meridional circulation in the radiative zone of the Sun. Even the rotation of the core of the Sun can now be studied thanks to various methods, such as dynamics of the gravitational moments and of course, helioseismology, through g-modes analysis. Moreover, the magnetic ?eld is strongly linked to the matter motions in the solar plasma. The solar magnetic ?eld can be measured only at the surface or in theupperlayers.Itistheproductoftheinternaldynamoorofthelocaldynamos if they exist – in any case magnetic ?eld and rotation cannot thus be separated.
Author: C. Aerts
Publisher: Springer Science & Business Media
ISBN: 1402058039
Category : Science
Languages : en
Pages : 872
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Book Description
Understanding the stars is the bedrock of modern astrophysics. Stars are the source of life. The chemical enrichment of our Milky Way and of the Universe withallelementsheavierthanlithiumoriginatesintheinteriorsofstars.Stars arethe tracersofthe dynamics ofthe Universe,gravitationallyimplying much more than meets the eye. Stars ionize the interstellar medium and re-ionized the early intergalactic medium. Understanding stellar structure and evolution is fundamental. While stellar structure and evolution are understood in general terms, we lack important physical ingredients, despite extensive research during recent decades.Classicalspectroscopy,photometry,astrometryandinterferometryof stars have traditionally been used as observational constraints to deduce the internal stellar physics. Unfortunately, these types of observations only allow the tuning of the basic common physics laws under stellar conditions with relatively poor precision. The situation is even more worrisome for unknown aspects of the physics and dynamics in stars. These are usually dealt with by using parameterised descriptions of, e.g., the treatments of convection, rotation,angularmomentumtransport,theequationofstate,atomicdi?usion andsettlingofelements,magneto-hydrodynamicalprocesses,andmore.There is a dearth of observational constraints on these processes, thus solar values areoftenassignedtothem.Yetitishardtoimaginethatonesetofparameters is appropriate for the vast range of stars.
Author: Santi Cassisi
Publisher: John Wiley & Sons
ISBN: 3527665544
Category : Science
Languages : en
Pages : 506
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Book Description
The book discusses the theoretical path to decoding the information gathered from observations of old stellar systems. It focuses on old stellar systems because these are the fossil record of galaxy formation and provide invaluable information ont he evolution of cosmic structures and the universe as a whole. The aim is to present results obtained in the past few years for theoretical developments in low mass star research and in advances in our knowledge of the evolution of old stellar systems. A particularly representative case is the recent discovery of multiple stellar populations in galactic globular clusters that represents one of the hottest topics in stellar and galactic astrophysics and is discussed in detail. Santi Cassisi has authored about 270 scientific papers, 150 of them in peer-reviewed journals, and the title Evolution of Stars and Stellar Populations.
