Download or read book On the Formation of Hydrogen deficient Post AGB Stars written by F. Herwig and published by . This book was released on 1999 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Post AGB Objects as a Phase of Stellar Evolution written by R. Szczerba and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: The term proto-planetary nebulae (PPNe) in the context of the late stages of stellar evolution was created only slightly more than 20 years ago to express the belief that in the near future these objects will become planetary nebulae (PNe). The first proto-planetary nebulae (called also post-Asymptotic Giant Branch, or shortly post-AGB objects) AFGL 2688 and AFGL 618 were discovered in mid seventies in course of the Air Force Sky Survey. Investigation of this phase of stellar evolution developed very rapidly in 1980's after the IRAS mission when it became clear that proto-planetary nebulae emit a significant part of their energy in the mid-and far-infrared. Hundreds of new candidates have been proposed but the recognition of the real proto-planetary nebulae is not a simple task and needs a substantial effort to exclude cases that represent different evolutionary stages. High resolution spectroscopy of stellar atmospheres is of much importance in this respect. Surprisingly, only a small group of central stars, the so called 21 11m emitters, show chemical signatures of the 3 rd dredge up process. Very recently, a more detailed studies of mid-infrared spectra from the Infrared Space Observatory (ISO) allow for a better understanding of chemical composition and evolution of circumstellar material around these stars. A new impetus in the field of proto-planetary nebulae research was started in the 1990's with high spatial resolution imaging in mid-infrared and optical wavelength ranges.
Download or read book Hydrogen deficient Stars written by Klaus Werner and published by . This book was released on 2008 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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.
Download or read book Hydrogen Deficient Stars and Related Objects written by K. Hunger and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 472 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Old Stellar Populations written by Santi Cassisi and published by John Wiley & Sons. This book was released on 2013-08-29 with total page 506 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Hydrogen Deficient Stars written by C. Simon Jeffery and published by . This book was released on 1996 with total page 530 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Light on the Composition of the Dust Surrounding Carbon Rich Stars written by S. Hony and published by Amsterdam University Press. This book was released on 2003-12-01 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt: Door middel van gedetailleerde studies aan de infrarood gegevens van oude sterren is het stof rond koolstofrijke Rode Reuzen onderzocht. De aanwezigheid van een aantal nieuwe materialen in de ruimte is ontdekt. Daarmee is een completer beeld van de samenstelling, locatie en het lot van het stof rond koolstofrijke oude sterren verkregen. Daarmee verschaffen de in dit proefschrift gepresenteerde studies een rijker inzicht in het stof rond oude sterren en deze sterren zelf.
Download or read book How are Hydrogen Deficient Stars Formed written by Detlef Schönberner and published by . This book was released on 1995 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astronomy with Radioactivities written by Roland Diehl and published by Springer Science & Business Media. This book was released on 2010-10-02 with total page 577 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the reader to the field of nuclear astrophysics, i.e. the acquisition and reading of measurements on unstable isotopes in different parts of the universe. The authors explain the role of radioactivities in astrophysics, discuss specific sources of cosmic isotopes and in which special regions they can be observed. More specifically, the authors address stars of different types, stellar explosions which terminate stellar evolutions, and other explosions triggered by mass transfers and instabilities in binary stars. They also address nuclear reactions and transport processes in interstellar space, in the contexts of cosmic rays and of chemical evolution. A special chapter is dedicated to the solar system which even provides material samples. The book also contains a description of key tools which astrophysicists employ in those particular studies and a glossary of key terms in astronomy with radioactivities.
Download or read book Allen s Astrophysical Quantities written by Clabon Walter Allen and published by Springer Science & Business Media. This book was released on 2000 with total page 748 pages. Available in PDF, EPUB and Kindle. Book excerpt: This new edition of Allen's classic "Astrophysical Quantities" belongs on every astronomer's bookshelf. It has been thoroughly revised and updated by a team of internationally renowned team of astronomers and astrophysicists. Topics covered include: * 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 * 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
Download or read book Astrophysics with Radioactive Isotopes written by Roland Diehl and published by Springer. This book was released on 2018-10-11 with total page 674 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dealing with astrophysics derived from the radiation emitted by radioactive atomic nuclei, this book describes the different methods used to measure cosmic radio-isotopes. It demonstrates how this astronomical window has contributed to the understanding of the sources and the chemical evolution of cosmic gas. Reference materials and explanations are included for students in advanced stages of their education. Nuclear reactions in different sites across the universe lead to the production of stable and unstable nuclei. Their abundances can be measured through different methods, allowing to study the various nuclear processes taking place in cosmic environments. Nucleosynthesis is the cosmic formation of new nuclear species, starting from hydrogen and helium resulting from the big bang origins. Stars create and eject synthesized nuclei during their evolution and explosions. Incorporation of the new interstellar composition into next-generation stars characterises the compositional (chemical) evolution of cosmic gas in and between galaxies. Radioactive species have unique messages about how this occurs. Since the first Edition of this book published in 2011 with the title Astronomy with Radioactivities, long-awaited new direct observations of supernova radioactivity have been made and are now addressed in two updated chapters dealing with supernovae. In this second Edition, the advances of recent years beyond one-dimensional treatments of stellar structure and stellar explosions towards 3-dimensional models have been included, and led to significant re-writings in Chapters 3-5. The sections on the Solar System origins have been re-written to account for new insights into the evolution of giant molecular clouds. The chapter on diffuse radioactivities now also includes material measurements of radioactivities in the current solar system, and their interpretations for recent nucleosynthesis activity in our Galaxy. Significant new results on gamma-rays from positron annihilations have been accounted for in that chapter, and led to new links with nucleosynthesis sources as well as interstellar transport processes. A new chapter now provides a description of interstellar processes often called 'chemical evolution', thus linking the creation of new nuclei to their abundance observations in gas and stars. The experimental / instrumental chapters on nuclear reaction measurements, on gamma-ray telescopes, and pre-solar grain laboratories have been updated. Moreover, new windows of astronomy that have been opened up in recent years have been included in the discussions of the multi-messenger approach that broadens the basis for astrophysical insights.
Download or read book Literature 1997 Part 1 written by Astronomisches Rechen-InstitutARI and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 1746 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts is devoted to the recording, summarizing and indexing of astronomical publications throughout the world. Two volumes are scheduled to appear per year. Volume 67 records 10,903 papers covering besides the classical fields of astronomy and astrophysics such matters as space flights related to astronomy, lunar and planetary probes and satellites, meteorites and interplanetary matter, X rays and cosmic rays, quasars and pulsars. The abstracts are classified under more than one hundred subject categories thus permitting quick surveying of the bulk of material published on the same topic within six months. For instance, this volume records 119 papers on minor planets, 155 papers on supernovae, and 554 papers on cosmology.
Download or read book White Dwarf Atmospheres and Circumstellar Environments written by Donald W. Hoard and published by John Wiley & Sons. This book was released on 2012-09-19 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by selected astronomers at the forefront of their fields, this timely and novel book compiles the latest results from research on white dwarf stars, complementing existing literature by focusing on fascinating new developments in our understanding of the atmospheric and circumstellar environments of these stellar remnants. Complete with a thorough refresher on the observational characteristics and physical basis for white dwarf classification, this is a must-have resource for researchers interested in the late stages of stellar evolution, circumstellar dust and nebulae, and the future of our own Solar System.
Download or read book Planetary Nebulae written by Harm J. Habing and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 543 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Asymptotic Giant Branch Stars written by Harm J. Habing and published by Springer Science & Business Media. This book was released on 2004 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with stars during a short episode before they undergo a ma jor, and fatal, transition. Soon the star will stop releasing nudear energy, it will become a planetary nebula for abrief but poetic moment, and then it will turn into a white dwarf and slowly fade out of sight. Just before this dramatic change begins the star has reached the highest luminosity and the largest diameter in its existence, and while it is a star detectable in galaxies beyond the Local Group, its structure contains already the inconspicuous white dwarf it will become. It is called an "asymptotic giant branch star" or "AGB star". Over the last 30 odd years AGB stars have become a topic of their own although individual members of this dass had already been studied for cen turies without realizing what they were. In the early evolution, so called "E-AGB"-phase, the stars are a bit bluer than, but otherwise very similar to, what are now called red giant branch stars (RGB stars). It is only in the sec ond half of their anyhow brief existence that AGB stars differ fundamentally from RGB stars.
Download or read book Interacting Winds from Massive Stars written by A. F. J. Moffat and published by . This book was released on 2002 with total page 720 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Angular Momentum and Mass Loss for Hot Stars written by L.A. Willson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
