Author: Luis A. Balona
Publisher: Springer Science & Business Media
ISBN: 9401110301
Category : Science
Languages : en
Pages : 554
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Book Description
In this Symposium, researchers specializing in pulsation, rotation, magnetic fields and stellar winds are brought together for the first time in order to broaden our understanding of O and B stars. Thanks to advances in digital spectroscopy, new types of pulsating B stars have been discovered. The pulsations can be understood in terms of the recent revision of metal opacities, but the effects of rapid rotation and magnetic fields need further study. Observations in the UV and X-ray regions demonstrate that many B and Be stars show other activity, besides pulsation which is not yet understood. The reason for the enhanced mass loss in Be stars is a question which dominates the Symposium and which remains unanswered, although it is surely to be found in activity at or near the photosphere coupled with rotation. It is shown that the geometry of the circumstellar envelopes around Be stars is indeed a flattened disk as they can now be optically resolved. The variability of radiatively-driven winds from O and B stars are likely related to the rotation of the star. This underlines the central theme of the book: that the various phenomena seen in these stars cannot be studied in isolation.
Author: R. Stalio
Publisher: Springer Science & Business Media
ISBN: 9400930291
Category : Science
Languages : en
Pages : 332
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Book Description
Stellar mass loss is an essential part of the cycling of material from the interstellar medium into stars and back, and must be understood if we are to model processes on galactic to cosmological scales. The study of stellar winds and the effects of stellar mass loss has reached a particularly exciting stage where observational capabilities are increasingly able to provide interesting constraints on models and theories. Recent resu1ts from theoretical and observational work for both hot and cool stars with substantial winds have led to the suggestion that a combination of pulsation with other mechanisms makes for particularly efficient mass loss from stars. This provided the original motivation for the organization of this workshop. The conference was organized along relatively conventional lines according to the types of objects being scrutinized. However the true unity of the proceedings comes from the interplay of the mechanisms involved. For example, for the cool, luminous Mira variables, pulsation leads to shock waves that extend the atmosphere, enhancing dust formation; radiation pressure on dust drives the wind, cooling the atmosphere and in some cases suppressing the shocks. Similarly for the Be stars, both pulsation (in this case, non-radial) and radiation pressure (due to UV resonance lines) are expected to be important, and this expectation is at least qualitatively borne out by the observations.
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: J.C. Suárez
Publisher: Springer Science & Business Media
ISBN: 3642296300
Category : Science
Languages : en
Pages : 285
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Book Description
Analyses of photometric time series obtained from the MOST, CoRoT and Kepler space missions were presented at the 20th conference on Stellar Pulsations (Granada, September 2011). These results are leading to a re-appraisal of our views on stellar pulsation in some stars and posing some new and unexpected challenges. The very important and exciting role played by innovative ground-based observational techniques, such as interferometric measurements of giant pulsating stars and high-resolution spectroscopy in the near infrared, is also discussed. These Proceedings are distinguished by the format of the conference, which brings together a variety of related but different topics not found in other meetings of this nature.
Author: A.J. Willis
Publisher: Springer Science & Business Media
ISBN: 9401708037
Category : Science
Languages : en
Pages : 394
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Book Description
Throughout his career Sir Robert Wilson has demonstrated that advances in a wide variety of fields in astrophysics and laboratory physics are achievable through the application of fundamental plasma spectroscopy. His work has included: optical studies that probed the nature of interstellar dust and first revealed the existence of O star winds; vacuum ultraviolet and X-ray diagnosis of fusion plasmas; rocket ultraviolet and X-ray observations of the Sun; and the conception, development and use of the International Ultraviolet Explorer (IUE) satellite which has contributed greatly to stellar, interstellar and extragalactic astrophysics. This volume contains reviews honouring Sir Robert and reflecting his interests.
Author: Lex Kaper
Publisher: Springer Science & Business Media
ISBN: 3540685979
Category : Science
Languages : en
Pages : 426
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Book Description
It is well known that stellar winds are variable, and the fluctuations are often cyclical in nature. This property seems to be shared by the winds of cool and hot stars, even though their outflows are driven by fundamentally different physical mechanisms. Since very similar models have been proposed to explain the cyclical wind variations observed in a wide variety of stars, the time was ripe for astrophysicists from many different sub-disciplines to present the state of the art in a concise form. The proceedings will provide a useful, up-to-date overview of the observations, interpretation, and modelling of the time-dependent mass outflows from all sorts of stars.
Author: Mariejo Goupil
Publisher: Springer
ISBN: 364233380X
Category : Science
Languages : en
Pages : 265
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Book Description
This volume synthesizes the results of work carried out by several international teams of the SIROCO (Seismology for Rotation and Convection) collaboration. It provides the theoretical background required to interpret the huge quantity of high-quality observational data recently provided by space experiments such as CoRoT and Kepler. Asteroseismology allows astrophysicists to test, to model and to understand stellar structure and evolution as never before. The chapters in this book address the two groups of topics summarized as "Stellar Rotation and Associated Seismology" as well as "Stellar Convection and Associated Seismology". The book offers the reader solid theoretical background knowledge and adapted seismic diagnostic techniques.
Author: Tomokazu Kogure
Publisher: Springer Science & Business Media
ISBN: 0387689958
Category : Science
Languages : en
Pages : 544
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Book Description
Emission line stars are attractive to many people because of their spectacular phenomena and their amazing varieties and variability. This book offers general information on emission line stars, starting from a brief introduction to stellar astrophysics and then moving to a broad overview of emission line stars including early and late type stars as well as pre-main sequence stars.
Author: Clabon Walter Allen
Publisher: Springer Science & Business Media
ISBN: 9780387951898
Category : Science
Languages : en
Pages : 746
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Book Description
This new fourth edition of Allen's classic Astrophysical Quantities belongs on every astronomer's bookshelf. It has been thoroughly revised and brought up to date by a team of more than ninety internationally renowned astronomers and astrophysicists. While it follows the basic format of the original, this indispensable reference has grown to more than twice the size of the earlier editions to accommodate the great strides made in astronomy and astrophysics. It includes detailed tables of the most recent data on: - General constants and units - Atoms, molecules, and spectra - Observational astronomy at all wavelengths from radio to gamma-rays, and neutrinos - Planetary astronomy: Earth, planets and satellites, and solar system small bodies - The Sun, normal stars, and stars with special characteristics - Stellar populations - Cataclysmic and symbiotic variables, supernovae - Theoretical stellar evolution - Circumstellar and interstellar material - Star clusters, galaxies, quasars, and active galactic nuclei - Clusters and groups of galaxies - Cosmology. As well as much explanatory material and extensive and up-to-date bibliographies.
Author: D. Vanbeveren
Publisher: Springer Science & Business Media
ISBN: 9781402003769
Category : Science
Languages : en
Pages : 360
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Book Description
The evolution of galaxies is governed mainly by the evolution of massive stars whereas the evolution of a massive star depends primarily on its mass, chemical composition and on whether or not the star is a Single object or a binary component. To study the evolution of galaxies, it is therefore essential to know how stellar masses are distributed at birth, how many stars are formed in binaries, and what the mass ratio and orbital period distribution of binaries look like. Massive stars are intrinsically the brightest stars, so that it may be possible to discover their properties in distant groups prOvided that large telescopes can be used for basic stellar observations. However, until now the observations of massive stars have been reasonably complete only for a small region of our own Galaxy (~ 3 kpc from the Sun). One hopes that the conclusions resulting from these observations hold for the whole Galaxy, for the whole cosmos. With 'The Brightest Stars' of De Jager (1980) in mind, the present monograph is an addendum and an update in which we discuss the observations of 'The Brightest Binaries' in the framework of stellar evolution. A small or intermediate mass star close to the Sun may look brighter than a massive one far away. However, within volume limited star samples, the massive stars are on average also the brightest ones. In the present monograph (similarly as in the work of De Jager), bright means massive. The book consists of four main chapters.
