Hydrogen Deficient Stars and Related Objects
Hydrogen Deficient Stars and Related Objects

Author: K. Hunger

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 472

ISBN-13: 9400947445

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The first helium star was discovered in 1942, the first scientific meeting on the subject, however, took place in 1985. The meeting was hence long overdue for, in the meantime, a substantial amount of material had been accumulated by a rather small, but active scientific community. Hence, it appeared necessary to review the field in order to define the subject, assess its present status and discuss future developments. Hydrogen deficiency is a widespread phenomenon, occurring in a large variety of stellar and nonstellar objects. It can be readily detected in B stars as these exhibit both hydrogen and helium lines, if the elements are present in appreciable amounts. It becomes less manifest in cool stars, where the temperature is too low to excite helium and where one has to devise indirect methods for proving hydrogen deficiency. Clearly, it was not possible to discuss the whole complex of hydrogen deficiency, i.e. in both stars and diffuse matter, but rather to concentrate on the issue of helium stars.

Hydrogen-deficient Stars
Hydrogen-deficient Stars

Author: Klaus Werner

Publisher:

Published: 2008

Total Pages: 424

ISBN-13:

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"These are the proceedings of a conference on Hydrogen-Deficient Stars held at the University of Tübingen, Germany, from September 17-21 2007. This conference was the third in a series of international colloquia on this topic. The first one took place in Mysore, India in 1985, and the second one a decade alter, 1995 in Bamberg, Germany. Twelve years later it was considered useful to gather again to discuss the progress and the future directions in this field. At the conference 68 participants from 20 countries presented 25 invited talks, 27 contributed talks, and 16 posters. Hydrogen-deficiency is exhibited by many evolved high-and low-mass stars. Therefore research on hydrogen-deficient stars is quite diverse since such stars are found in almost every region of the Hertzsprung-Russell diagram. The stellar classes discussed in detail at the conference were: R Coronae Borealis stars, extreme helium stars, Wolf-Rayet central stars of planetary nebulae, PG 1159 stars and related objects, white dwarfs of spectral type DO, DB, and DQ, and helium-rich subdwarf O and B stars. Also highlighted were hydrogen-deficient stars in close binary systems (AM Cvn and ultracompact low-mass X-ray binaries), massive Wolf-Rayet Stars and their relation to Type I supernovae and Gamma-ray bursts. The different classes of objects discussed in this volume are grouped by spectral and pulsational characteristics, by evolutionary scenarios such as late helium flashes and double-degenerate mergers, and by links among the classes."--Publisher's website.

The Analysis of Starlight
The Analysis of Starlight

Author: John B. Hearnshaw

Publisher: Cambridge University Press

Published: 2014-03-17

Total Pages: 385

ISBN-13: 1107782910

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First published in 1986, this is the story of the analysis of starlight by astronomical spectroscopy. Beginning with Joseph Fraunhofer's discovery of spectral lines in the early nineteenth century, this new edition continues the story through to the year 2000. In addition to the key discoveries, it presents the cultural and social history of stellar astrophysics by introducing the leading astronomers and their struggles, triumphs and disagreements. Basic concepts in spectroscopy and spectral analysis are included, so both observational and theoretical aspects are described, in a non-mathematical framework. This new edition covers the final decades of the twentieth century, with its major advances in stellar astrophysics: the discovery of extrasolar planets, new classes of stars and the observation of the ultraviolet spectra of stars from satellites. The in-depth coverage makes it essential reading for graduate students working in stellar spectroscopy, professional and amateur astronomers, and historians of science.

Principles and Perspectives in Cosmochemistry
Principles and Perspectives in Cosmochemistry

Author: Aruna Goswami

Publisher: Springer Science & Business Media

Published: 2010-03-19

Total Pages: 427

ISBN-13: 3642103529

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A fundamental question in contemporary astrophysics is the origin of the elements. Cosmochemistry seeks to answer when, how and where the chemical elements arose. Quantitative answers to these fundamental questions require a multi-disciplinary approach involving stellar evolution, explosive nucleosynthesis and nuclear reactions in different astrophysical environments. There remain, however, many outstanding problems and cosmochemistry remains a fertile area of research. This book is among the first in recent times to put together the essentials of cosmochemistry, combining contributions from leading astrophysicists in the field. The chapters have been organized to provide a clear description of the fundamentals, an introduction to modern techniques such as computational modelling, and glimpses of outstanding issues.

Transactions of the International Astronomical Union: Reports on Astronomy
Transactions of the International Astronomical Union: Reports on Astronomy

Author: C. de Jager

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 745

ISBN-13: 9401025878

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This volume contains the fifteenth tri-annual reports of the Presidents of the forty Commissions of the International Astronomical Union; it refers to the progress in our discipline during the three years 1970, 1971 and 1972. As compared to earlier volumes a gradual change in character is unmistakable. The ever increasing flow of publications, combined with the obvious necessity to keep the Reports at a reasonable size and price level has gradually forced the Commission Presidents to be more selective than before in drafting their Reports. I have certainly stimulated them into that direction - in order that Reports like these be valuable and lasting, it seems imperative that the individual contributions have the character of a critical overall review, where a fairly complete summary is given of the major develop ments and discoveries of the past three years, and in which the broad developments and new trends be clearly outlined, while at the same time essential problems for future research are identified. With respect to the latter item I have suggested the Commission Presidents to add to their reports a brief section on scientific priorities for future research in the field of their Commissions. In order to save space I have suggested to Commission Presidents that references to published papers are given on the basis of their number in the published issues of Astronomy and Astrophysics Abstracts. For instance, the indication (06. 078. 019) or (AAA 06. 078.

Planetary Nebulae
Planetary Nebulae

Author: Harm J. Habing

Publisher: Springer Science & Business Media

Published: 2012-12-06

Total Pages: 543

ISBN-13: 9401152446

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Planetary nebulae present a fascinating range of shapes and morphologies. They are ideal laboratories for the study of different astrophysical processes: atomic physics, radiative transfer, stellar winds, shocks, wind-wind interaction, and the interaction between stellar winds and the interstellar medium. In addition, planetary nebulae provide information about the late stages of stellar evolution. In the last five years studies of planetary nebulae have progressed very rapidly and new phenomena and insights have been gained. This is partly due to new observations (e.g. from the Hubble Space Telescope, the ISO satellite and new infrared and millimeter spectrographs) and partly to the advancement of hydrodynamic simulations of the structures of planetary nebulae (PN). Many of these new results were reported at IAU Symposium 180 in Groningen, the Netherlands, on August 26 to 30, 1996. This symposium was dedicated to one of the pioneers of PN research: Stuart Pottasch. These proceedings contain chapters on: Introduction to PN with the basic parameters Distances of PN The central stars of PN The envelopes of PN The evolution from AGB to PN The evolution from PN to white dwarfs PN in the galactic context PN in extragalactic systems The future of PN research . The book contains 29 reviews and more than 200 shorter contributions.

Asteroseismology
Asteroseismology

Author: C. Aerts

Publisher: Springer Science & Business Media

Published: 2010-01-19

Total Pages: 872

ISBN-13: 1402058039

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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.