Instability and Variability of Hot-Star Winds

Instability and Variability of Hot-Star Winds PDF Author: Anthony F.J. Moffat
Publisher: Springer Science & Business Media
ISBN: 9401103151
Category : Science
Languages : en
Pages : 475

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Book Description
This specialized workshop was conceived during the workshop on "Non isotropic and Variable Outflows from Stars", which was held at the Space Telescope Science Institute in October, 1991. At that meeting, the four of us collectively decided that the time was ripe for an even more focussed discussion of the basic issues in the area of hot-star wind instability and its observable manifestations. Not that the big problems have been solved! Rather, we are currently in a phase of rapid development, both with regard to the models and to the observations. The key issue at this new workshop would be to decide how the time-dependent structures observed in hot-star winds (e. g. , NACs, DACs, blobs, clumps, filaments, shells, puffs, jets, etc. ) relate to radiative and other instabilities. Further questions concern the role of turbulence and the nature of its driver, and the effect of stellar rotation, pulsation, and magnetic fields on time-dependent phenomena in hot-star winds. Of no less importance is the impact of stellar wind variability on the derivation of mass-loss rates, on stellar evolution, and on momentum/energy deposition in the interstellar medium. To attain our goal of maximum confrontation (in the positive sense!) we decided: (1) to limit the workshop to the observers and theoreticians most active in this field in the world; (2) to insist that virtually all participants present a talk, thereby avoiding the distraction of poster sessions; and (3) to allocate approximately half of the allotted time to discussion.

Instability and Variability of Hot-Star Winds

Instability and Variability of Hot-Star Winds PDF Author: Anthony F.J. Moffat
Publisher: Springer Science & Business Media
ISBN: 9401103151
Category : Science
Languages : en
Pages : 475

Get Book Here

Book Description
This specialized workshop was conceived during the workshop on "Non isotropic and Variable Outflows from Stars", which was held at the Space Telescope Science Institute in October, 1991. At that meeting, the four of us collectively decided that the time was ripe for an even more focussed discussion of the basic issues in the area of hot-star wind instability and its observable manifestations. Not that the big problems have been solved! Rather, we are currently in a phase of rapid development, both with regard to the models and to the observations. The key issue at this new workshop would be to decide how the time-dependent structures observed in hot-star winds (e. g. , NACs, DACs, blobs, clumps, filaments, shells, puffs, jets, etc. ) relate to radiative and other instabilities. Further questions concern the role of turbulence and the nature of its driver, and the effect of stellar rotation, pulsation, and magnetic fields on time-dependent phenomena in hot-star winds. Of no less importance is the impact of stellar wind variability on the derivation of mass-loss rates, on stellar evolution, and on momentum/energy deposition in the interstellar medium. To attain our goal of maximum confrontation (in the positive sense!) we decided: (1) to limit the workshop to the observers and theoreticians most active in this field in the world; (2) to insist that virtually all participants present a talk, thereby avoiding the distraction of poster sessions; and (3) to allocate approximately half of the allotted time to discussion.

Astrophysical and Laboratory Plasmas

Astrophysical and Laboratory Plasmas PDF 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.

The Impact of Long-Term Monitoring on Variable Star Research

The Impact of Long-Term Monitoring on Variable Star Research PDF Author: C. Sterken
Publisher: Springer Science & Business Media
ISBN: 9401111642
Category : Science
Languages : en
Pages : 471

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Book Description
Long-term monitoring is of fundamental significance in solving many important problems in astrophysics and, furthermore, has unequalled value in extending observational runs with small telescopes for the education of young astronomers in order to teach them how to secure high-quality observational data over many years. The Impact of Long-Term Monitoring on Variable Star Research contains reports based on the analysis of data collected in the visible, IR and radio measurement ranges, as well as the design and history of well known photometric systems. Though the reporting of novel results forms an important part of the book, there are also reports of eight discussion sessions covering more general areas, such as extinction monitoring, the problems of archival storage of astronomical data, service observation, the role played by long-term monitoring in graduate teaching and thesis supervision, the interplay between the great observational effort and theory, the contribution of LTM to new knowledge of fundamental data, and the increasing decommissioning of telescopes of modest aperture.

Encyclopedia of Astronomy & Astrophysics

Encyclopedia of Astronomy & Astrophysics PDF Author: P Murdin
Publisher: CRC Press
ISBN: 1000523039
Category : Science
Languages : en
Pages : 5610

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Book Description
In a unique collaboration, Nature Publishing Group and Institute of Physics Publishing have published the most extensive and comprehensive reference work in astronomy and astrophysics. This unique resource covers the entire field of astronomy and astrophysics and this online version includes the full text of over 2,750 articles, plus sophisticated search and retrieval functionality and links to the primary literature. The Encyclopaedia's authority is assured by editorial and advisory boards drawn from the world's foremost astronomers and astrophysicists. This first class resource is an essential source of information for undergraduates, graduate students, researchers and seasoned professionals, as well as for committed amateurs, librarians and lay people wishing to consult the definitive astronomy and astrophysics reference work.

Pulsation, Rotation and Mass Loss in Early-Type Stars

Pulsation, Rotation and Mass Loss in Early-Type Stars PDF 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.

The Century of Space Science

The Century of Space Science PDF Author: J.A. Bleeker
Publisher: Springer Science & Business Media
ISBN: 9401003203
Category : Science
Languages : en
Pages : 1819

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Book Description
One of the most attractive features of the young discipline of Space Science is that many of the original pioneers and key players involved are still available to describe their field. Hence, at this point in history we are in a unique position to gain first-hand insight into the field and its development. To this end, The Century of Space Science, a scholarly, authoritative, reference book presents a chapter-by-chapter retrospective of space science as studied in the 20th century. The level is academic and focuses on key discoveries, how these were arrived at, their scientific consequences and how these discoveries advanced the thoughts of the key players involved. With over 90 world-class contributors, such as James Van Allen, Cornelis de Jager, Eugene Parker, Reimar Lüst, and Ernst Stuhlinger, and with a Foreword by Lodewijk Woltjer (past ESO Director General), this book will be immensely useful to readers in the fields of space science, astronomy, and the history of science. Both academic institutions and researchers will find that this major reference work makes an invaluable addition to their collection.

Wolf-Rayet Stars

Wolf-Rayet Stars PDF Author: Karel A. van der Hucht
Publisher: Springer Science & Business Media
ISBN: 9401102058
Category : Science
Languages : en
Pages : 598

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Book Description
In this IAU Symposium on Wolf--Rayet stars, binary aspects received ample attention, notably because of the recognition that many observations of spectral and photometric variability at all accessible wavelengths are related to colliding winds or other forms of wind interaction. The basic structure of the conference and its proceedings is basic parameters and general properties of WR stars; state of the art model atmospheres for WR stars, anisotropic mass loss and disk formation of WR stars, properties of WR binaries; influence of stellar winds on mass transfer in hot massive binary evolution; dust formation near WR stars and other circumstellar phenomena; and hydrodynamics and high-energy physics of colliding winds in WR+O binaries and of WR winds interacting with compact objects. Within this framework 20 invited reviews, 38 invited oral contributions, and 76 poster papers were presented at the Symposium, entertaining 111 astronomers from 24 countries. These proceedings provide up-to-date information on all aspects of Wolf--Rayet atmospheres, binaries, and colliding winds.

Shocks in Astrophysics

Shocks in Astrophysics PDF Author: T.J. Millar
Publisher: Springer Science & Business Media
ISBN: 9400916248
Category : Science
Languages : en
Pages : 328

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Book Description
This volume contains the proceedings of an international conference on Shocks in Astrophysics held at UMIST, Manchester, England from January 9-12, 1995. The study of interstellar and circumstellar gas dynamics has a long and distinguished history in Manchester and has been almost entirely concentrated in the school founded by Franz Kahn in the Astronomy Department, University of Manchester. In January 1993, one of us (AR) was appointed to the faculty of the Astrophysics Group in the Department of Mathematics at UMIST and astrophysical gas dynam ics became a major interest of the Group. The subject of this conference was chosen partly for the topicality of the subject matter and partly to help synthesise this expertise with the expertise in interstellar chemistry already present in the Group. The first fruits of this synthesis are contained in this volume. As it happened, this conference celebrated, not so much the beginnings of a long and fruitful collabo ration, but rather gave many of Alex's friends the chance to say a fond farewell as he departed UMIST at the end of January 1995 to take up a chair at UNAM, Mexico City. The core of this volume consists of twelve review articles, marked (R) in the list of contents, incorporating observational and theoretical studies of shock waves in a variety of situations from Herbig-Haro objects to Supernova Remnants to Active Galactic Nuclei. We have also included the contributed (C) and poster (P) papers.

Dust and Molecules in Evolved Stars

Dust and Molecules in Evolved Stars PDF Author: I. Cherchneff
Publisher: Springer Science & Business Media
ISBN: 9401713073
Category : Science
Languages : en
Pages : 392

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Book Description
Dust and molecules are found in a large variety of astrophysical environments, in particular in the circumstellar material ejected by evolved stars. This book brings together the leading astronomers and astrophysicists in the field of molecular astrophysics and stellar physics to discuss the important issues of dust and molecular formation, the role of solids in circumstellar environments, molecules as probes of circumstellar parameters, the stellar contribution to the enrichment of the Galaxy, and the latest observational data in various wavelength domains, in partiular in the infrared with results from the Infrared Space Observatory. The astrophysical senarios include late-type stars, novae, Wolf-Rayet stars, Luminous Blue Variables and supernovae. Audience: Researchers and graduate students in the fields of stellar physics, stellar evolution and astrochemistry.

Introduction to Stellar Winds

Introduction to Stellar Winds PDF 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.