Download or read book Accuracy of Element Abundances from Stellar Atmospheres written by Rainer Wehrse and published by . This book was released on 1990 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Accuracy of Element Abundances from Stellar Atmospheres written by Rainer Wehrse and published by Springer. This book was released on 2014-10-09 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: To get a reasonably realistic picture of the structure and evolution of stars one needs to know accurately the abundances of chemical elements and their isotopes in the stellar atmosphere and in the galactic environment of the stars. The articles collected in this volume give a modern review of the abundance accuracies for main-sequence stars. After a general introduction in the first part the accuracies of atomic transition probabilities, ionization and excitation cross-sections, and line broad- ening data are discussed. In the second part the specific problems and results for different stellar types are presented, and, finally, an overview on the possibilities of abundance determinations for stars outside the Galaxy is given.
Download or read book Accuracy of Element Abundances from Stellar Atmospheres written by International Astronomical Union. General Assembly and published by Springer. This book was released on 1990-03-21 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: To get a reasonably realistic picture of the structure and evolution of stars one needs to know accurately the abundances of chemical elements and their isotopes in the stellar atmosphere and in the galactic environment of the stars. The articles collected in this volume give a modern review of the abundance accuracies for main-sequence stars. After a general introduction in the first part the accuracies of atomic transition probabilities, ionization and excitation cross-sections, and line broad- ening data are discussed. In the second part the specific problems and results for different stellar types are presented, and, finally, an overview on the possibilities of abundance determinations for stars outside the Galaxy is given.
Download or read book Setting the Scene for Gaia and LAMOST IAU S298 written by Sofia Feltzing and published by Cambridge University Press. This book was released on 2014-01-30 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gaia is an ambitious satellite mission to chart a three-dimensional map of the Milky Way. By measuring the proper motions and parallaxes for a billion stars, Gaia is set to transform the way we study the composition, formation and evolution of our galaxy. Concurrently the LAMOST survey facility in China will make a complementary spectral survey of millions of objects in much of the northern sky. This volume, comprising the reviews and contributed talks presented at IAU Symposium 298, is an up-to-date review of what we know about the Milky Way as a galaxy prior to the launch of Gaia. It covers many topics including the status of dynamical simulations, photometric and spectroscopic surveys, and interstellar matter in the Milky Way, as well as detailed studies of stellar atmospheres. The expert reviews will interest all those working on Milky Way astronomy as well as galaxy formation and evolution.
Download or read book Determination of Atmospheric Parameters of B A F and G Type Stars written by Ewa Niemczura and published by Springer. This book was released on 2014-07-10 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the theory of stellar atmospheres. Almost everything we know about stars is by analysis of the radiation coming from their atmospheres. Several aspects of astrophysics require accurate atmospheric parameters and abundances. Spectroscopy is one of the most powerful tools at an astronomer’s disposal, allowing the determination of the fundamental parameters of stars: surface temperature, gravity, chemical composition, magnetic field, rotation and turbulence. These can be supplemented by distance measurements or pulsation parameters providing information about stellar interior and stellar evolution, otherwise unavailable. The volume is based on lectures presented at the Wrocław's Spectroscopic School aimed at training young researchers in performing quantitative spectral analysis of low-, mid-, and high-resolution spectra of B, A, and F-type stars.
Download or read book Stellar Atmospheres written by Cecilia Helena Payne Gaposchkin and published by . This book was released on 1925 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Original thesis submitted to Radcliffe College. The typescript is a summary of the thesis with handwritten ink insertions. The galley proof contains the full text and bears blue and graphite pencil markings. A library thesis use form is affixed to the bottom of the first page of the galley.
Download or read book Theory of Stellar Atmospheres written by Ivan Hubeny and published by Princeton University Press. This book was released on 2014-10-26 with total page 944 pages. Available in PDF, EPUB and Kindle. Book excerpt: The most authoritative synthesis of the quantitative spectroscopic analysis of stellar atmospheres This book provides an in-depth and self-contained treatment of the latest advances achieved in quantitative spectroscopic analyses of the observable outer layers of stars and similar objects. Written by two leading researchers in the field, it presents a comprehensive account of both the physical foundations and numerical methods of such analyses. The book is ideal for astronomers who want to acquire deeper insight into the physical foundations of the theory of stellar atmospheres, or who want to learn about modern computational techniques for treating radiative transfer in non-equilibrium situations. It can also serve as a rigorous yet accessible introduction to the discipline for graduate students. Provides a comprehensive, up-to-date account of the field Covers computational methods as well as the underlying physics Serves as an ideal reference book for researchers and a rigorous yet accessible textbook for graduate students An online illustration package is available to professors at press.princeton.edu
Download or read book Elements and the Cosmos written by Bernard Ephraim Julius Pagel and published by Cambridge University Press. This book was released on 1992-10-15 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: While there have been many books on cosmology and galactic and stellar evolution in which abundance analysis of astrophysical objects has played some part, this book is the first one for several years where specialists in the various relevant fields discuss the basis and implications of the subject as a whole. The major aim of the book is to bring together the results from high redshift studies and galactic studies in a coherent way and to cover relevant aspects of nuclear and atomic physics.
Download or read book The Light Element Abundances written by Philippe Crane and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first volume of a series on a regular up-to-date coverage of important developments in astronomy and astrophysics jointly published by ESO and Springer-Verlag. Here the reader finds a thorough review of the abundances of the elements up to Boron. Special emphasis is laid on primordial abundances of interest to cosmologists in particular, and on stellar production or destruction respectively. The articles written for researchers and graduate students cover theory and most recent data from telescope observations.
Download or read book Fundamental Stellar Properties The Interaction Between Observation and Theory written by Timothy R. Bedding and published by Springer Science & Business Media. This book was released on 2013-12-01 with total page 488 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Symposium began with a proposal for a meeting to honour Emer itus Professor Robert Hanbury Brown on the occasion of his 80th birthday. He requested that any such meeting should be on a topic that would be of benefit to the Sydney University Stellar Interferometer (SUSI) program. With SUSI and several other high angular resolution instruments either in operation or coming on line within the next decade, and with advances in astrometry, spectroscopy and in theoretical models of stellar atmospheres and interiors, it appeared to be both appropriate and timely to hold a symposium on "Fundamental Stellar Properties: the Interaction between Observation and Theory. " The emphasis of the meeting was on the critical assessment of the qual ity, accuracy, and prospects for improvement of the observational data and theoretical models, on the outstanding problems in stellar astrophysics, and on the feasibility of achieving the observational and theoretical advances required for their solution. Invited papers comprised the major part of the oral program and the speakers responded to the challenge issued by the Scientific Organising Committee to critically review the current status and prospects for their area of expertise. The Symposium was opened by the Chancellor of the University of Sydney, Emeritus Professor Dame Leonie Kramer, who welcomed the 126 participants from 22 countries on behalf of the University. The oral program included . 52 invited reviews and papers and 10 contributed papers.
Download or read book The Abundance of the Elements written by Lawrence Hugh Aller and published by . This book was released on 1961 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Three dimensional Non local Thermodynamic Equilibrium Radiative Transfer and Oxygen Abundances in Late type Stars written by Anish Mayur Amarsi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemical compositions of the atmospheres of late-type stars, as inferred from stellar spectroscopic analyses, provide vital clues to unravelling the history of stars, galaxies, and the cosmos as a whole. However, the vast majority of stellar spectroscopic analyses make at least two assumptions that severely limit their accuracy: that stellar atmospheres are one-dimensional (1D) and hydrostatic; and that the material in the line-forming regions is in local thermodynamic equilibrium (LTE). Real atmospheres of late-type stars have convective envelopes that require a 3D time-evolving hydrodynamical treatment, and also real atmospheres are generally not in LTE. In this thesis I develop tools for 3D non-LTE radiative transfer calculations in late-type stars, and use them to address two outstanding problems that are pertinent to oxygen, which is one of the most important elements in astronomy. First is the so-called solar mod- elling problem, wherein inferences about the structure of the Sun based on helioseismology are in significant disagreement with those inferences based on the current best estimate of the solar chemical composition (as deduced from spectroscopy) and standard solar interior models. It has been strongly argued in the literature that a higher solar oxygen abundance is needed to resolve this problem. Second is the so-called oxygen problem in metal-poor stars, wherein different oxygen abundance diagnostics give different oxygen abundances in metal-poor Milky Way disk and halo stars. In particular, this has meant that the Galactic [O/Fe] versus [Fe/H] trend, a key tracer of chemical evolution, is poorly constrained in the metal-poor regime. I present new 3D non-LTE analyses of oxygen and silicon lines in the solar spectrum. The inferred solar oxygen and silicon abundances, 8.70 ± 0.03 dex and 7.51 ± 0.03 dex respectively, are consistent with the current canonical values to within errors, so maintaining the status quo on the solar modelling problem. I also present 3D non-LTE spectra for atomic oxygen lines across a grid of 3D hydrodynamic model atmospheres. Such a grid facilitates 3D non-LTE analyses of stars other than the Sun. With this grid I present analyses of the [O/Fe] versus [Fe/H] trend from Galactic disk and halo stars, and I demonstrate that with accurate stellar parameters and 3D non-LTE modelling, concordant results can be achieved between the two key atomic oxygen diagnostics: the [Oi]630nm line, and the Oi 777 nm lines. Lastly, I present a 3D non-LTE analysis of Fe i and Fe ii lines in four metal- poor benchmark stars: HD84937, HD122563, HD140283, and G64-12. I demonstrate that the 3D non-LTE iron abundances are typically 0.1 dex higher than the corresponding 1D non-LTE iron abundances. 3D effects of this order need to be accounted for if the Galactic [O/Fe] versus [Fe/H] relationship is to be properly constrained.
Download or read book Spectral Line Formation written by John T. Jefferies and published by . This book was released on 1968 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to discuss certain aspects of the theory of the formation and analysis of the line spectrum of a hot gas. The underlying motivation for most of the studies discussed here lies in a desire to develop a physically sound procedure for interpreting the line spectrum of a stellar atmosphere ; correspondingly, the major emphasis is given to problems encountered in astrophysics.
Download or read book The Behavior of Chemical Elements in Stars written by Carlos Jaschek and published by Cambridge University Press. This book was released on 1995-06-08 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite more than one century of observational stellar spectroscopy, the resulting data are not available in an easily accessible format. The necessity of such basic information is greater than ever, because new wavelength regions (ultraviolet, infrared) are now accessible and because modern receivers can only analyze short stretches of spectra, so that a careful pre-selection of strategic elements is mandatory. This book presents a summary of our knowledge of the behavior of all chemical elements identified in stars, based on observations rather than on their interpretations. Whenever possible the behavior is described quantitatively, with the help of equivalent widths in different types of stars, or different ionization stages, for both absorption and emission features. It will be essential to the spectroscopist when confronted with questions like the following: . What is the behavior of europium in metallic line stars or in S-type stars? Are the neutral lines of this element visible, are they strengthened or weakened with regard to normal dwarfs? A huge amount of data has been gathered by experts in the field and presented in a way that will be invaluable to professional astrophysicists, cosmochemists and their students.
Download or read book Nucleosynthesis and Chemical Evolution of Galaxies written by Bernard Ephraim Julius Pagel and published by Cambridge University Press. This book was released on 2009-01-15 with total page 485 pages. Available in PDF, EPUB and Kindle. Book excerpt: A lucid introduction for advanced undergraduates and graduate students, and an authoritative overview for researchers and professional scientists.
Download or read book Precision Spectroscopy in Astrophysics written by Nuno C. Santos and published by Springer Science & Business Media. This book was released on 2008-01-28 with total page 664 pages. Available in PDF, EPUB and Kindle. Book excerpt: High-accuracy Doppler shift measurements and high-precision spectroscopy are primary techniques in the search for exo-planets. Further extremely interesting applications include the analysis of QSO absorption lines to determine the variability of physical constants and the analysis of the isotopic ratios of absorption lines both in stars and in QSOs, and the determination of stellar oscillations through radial velocity measurements. Since the use of high-precision/resolution spectroscopy is closely connected to the ability to collect a large number of photons, the scientific domains using this technique benefit tremendously from the use of 8-meter class telescopes and will fully exploit the tremendous gain provided by future Extremely Large Telescopes (ELTs). IR high-resolution spectroscopy should soon approach the same accuracy regime achieved in the optical range. This volume comprehensively covers the astrophysical and technical aspects of high-precision spectroscopy with an outlook to future developments, and represents a useful reference work for researchers in those fields.
Download or read book Stellar Atmospheres Beyond Classical Models written by L. Crivellari and published by Springer Science & Business Media. This book was released on 1991-07-31 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: The theory of stellar atmospheres is one of the most important branches of modern astrophysics. It is first of all a major tool for understanding all aspects of stars. As the physical properties of their outer layers can now be found with high precision, firm conclusions can be drawn about the internal structure and evolution of stars. Moreover, improvements in our knowledge of the chemical composition of stars is shedding new light on the chemical evolution of galaxies and of the Universe as a whole. Because the outer layers of stars are among the best-understood astrophysical objects, the theory of stellar atmospheres plays an important role in the study of many other types of objects. These include planetary nebulae, H II regions, interstellar matter, and objects of interest in high-energy astrophysics, such as accretion disks (close binaries, dwarf novae, cataclysmic variables, quasars, active galactic nuclei), pulsar magnetospheres, and Seyfert galaxies. Finally, as stars provide a laboratory in which plasmas can be studied under more extreme conditions than on earth, the study of stellar atmospheres has strong connections with modern physics. Astronomical observations provided a vital stimulus in the early stages of quantum theory and atomic physics; even today topics such as low-temperature dielectronic recombination develop hand in hand with the interpretation of stellar and nebular spectra. Early work on MHD was similiarly motivated. Many such connections remain to be explored.
