Download or read book Progress in Stellar Spectral Line Formation Theory written by J.E. Beckman and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spectral line formation theory is at the heart of astrophysical diagnostic. Our knowledge of abundances, in both stellar and interstellar contexts, comes almost enti rely from line analysis, as does a major fraction of our ability to model stellar atmospheres. As new facets of the universe become observable so the techniques of high reso lution spectroscopy are brought to bear, with great reward. Improved instruments, such as echelle spectrographs, employ ing detectors of high quantum efficiency, have revolutioned our ability to observe high quality line profiles, although until now this ability has been confined to the brightest stars. Fabry-Perot interferometers and their modern deriva tives are bringing new ranges of resolving power to studies of atomic and ionic interstellar lines, and of course radio techniques imply exceedingly high resolution for the cool interstellar medium of molecules and radicals. Telescopes in space are extending the spectral range of these types of observations. Already the Copernicus and IUE high resolution spectrographs have given us a tantalizing glimmer of what it will be like to obtain ultraviolet spectra with resolution and signal to noise ratio approaching those obtainable on the ground. Fairly soon Space Telescope will be producing high resolution spectroscopic data of unparal leled quali ty and distance range. As often happens in astro physics the challenge is now coming from the observers to the theorists to provide interpretational tools which are adequate to the state of the data.

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 Contribution to Spectral Type Theory written by and published by . This book was released on 1963 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Evolution of Peculiar Red Giant Stars written by International Astronomical Union. Colloquium and published by Cambridge University Press. This book was released on 1989-06-22 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Red giant stars are evolutionarily advanced objects in the closing stages of their nuclear burning lifetime. Observed with increasing spectral coverage they display a variety of unusual phenomena. Many are characterized by peculiar (non-solar) surface chemical compositions which provide otherwise unobtainable clues to interior nucleosynthesis, mixing and evolution. Others may have received their chemical peculiarities by mass transfer from a companion. This book reports on the proceedings of the International Astronomical Union Colloquium 106. It contains discussions on many aspects of these stars, combining theory and observation to interpret these objects in terms of their evolutionary history. There are 20 review papers, 69 abstracts and short contributed papers and a complete transcript of the valuable summary panel discussion. Professional astronomers will find this book useful as a reference work which incorporates current research on the modelling and evolution of these unstable stars.

Download or read book The Carbon Star Phenomenon written by International Astronomical Union. Symposium and published by Springer Science & Business Media. This book was released on 2000-07-31 with total page 672 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 177th Symposium of the International Astronomical Union, held in Antalya, Turkey, May 27-31, 1996

Download or read book Literature 1985 Part 1 written by S. Böhme and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 1157 pages. Available in PDF, EPUB and Kindle. Book excerpt: Astronomy and Astrophysics Abstracts aims to present a comprehensive documen tation of the literature concerning all aspects of astronomy, astrophysics, and their border fields. It is devoted to the recording, summarizing, and indexing of the relevant publications throughout the world. Astronomy and Astrophysics Abstracts is prepared by a special department of the Astronomisches Rechen-Institut under the auspices of the International Astronomical Union. Volume 39 records literature published in 1985 and received before August 15, 1985. Some older documents which we received late and which are not surveyed in earlier volumes are included too. We acknowledge with thanks contributions of our colleagues all over the world. We also express our gratitude to all organiza tions, observatories, and publishers which provide us with complimentary copies of their publications. On account of the introduction of an object index the scope of index information will be considerably enlarged beginning with this volume. In connection with the subject index an additional source to satisfy the needs of retrieval is opened up. Starting with Volume 33, all the recording, correction, and data processing work was done by means of computers. The recording was done by our technical staff members Ms. Helga Ballmann, Ms. Mona El-Choura, Ms. Monika Kohl, Ms. Sylvia Matyssek. Ms. Karin Burkhardt, Ms. Susanne Schlotelburg, and Mr. Stefan Wagner supported our task by careful proofreading. It is a pleasure to thank them all for their encouragement. Heidelberg, September 1985 The Editors Contents Introduction . . . . . . . . . . . .

Download or read book New Windows to the Universe written by International Astronomical Union and published by Cambridge University Press. This book was released on 1990-12-13 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Radiation Trapping in Atomic Vapours written by Andreas F. Molisch and published by Oxford University Press. This book was released on 1998 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation can be absorbed and re-emitted many times in atomic vapors before it reaches the boundaries of the container encasing the vapor. This effect is known as radiation trapping. It plays an important role practically everywhere atomic vapors occur, whether in spectroscopy, gas lasers, atomic line filters, the determination of atomic lifetimes, measurements of atomic interaction potentials, or electric discharge lamps. This book is the first to assemble all of the information necessary to handle practical problems related to radiation trapping, and it emphasizes both physical insights and mathematical methods. The introduction reviews resonance radiation and collision processes in atomic vapors. This is followed by detailed explanations of the physical effects and mathematical methods for various types of problems (e.g., with or without saturation, particle diffusion, reflecting cell walls). The last part of the book describes the applications of these methods to a variety of practical problems, such as cross-section measurements and the design of discharge lamps.

Download or read book Solar Photosphere Structure Convection and Magnetic Fields written by Jan Olof Stenflo and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solar and stellar photospheres constitute the layers most accessible to observations, forming the interface between the interior and the outside of the stars. The solar atmosphere is a rich physics laboratory, in which the whole spectrum of radiative, dynamical, and magnetic processes that tranfer energy into space can be observed. As the fundamental processes take place on very small spatial scales, we need high· resolution observations to explore them. On the other hand the small-scale processes act together to form global properties of the sun, which have their origins in the solar interior. The rapid advances in observational techniques and theoreticallllodelling over the past decade made it very timely to bring together scientists from east and west to the first lAU Symposium on this topic. The physics of the photosphere involves complicated interactions between magnetic fields, convection, waves, and radiation. During the past decade our understanding of these gener ally small-scale structures and processes has been dramatically advanced. New instrumen tations, on ground and in space, have given us new means to study the granular convection. Diagnostic methods in Stokes polarimetry have allowed us to go beyond the limitations of spatial resolution to explore the structure and dynamics of the subarcsec magnetic struc tures. Extensive numerical simulations of the interaction between convection and magnetic fields using powerful supercomputers are providing deepened physical insight. Granulation, magnetic fields, and dynamo processes are being explored in the photospheres of other stars, guided by our improved understanding of the solar photosphere.

Download or read book Solar Variability and Climate written by E. Friis-Christensen and published by Springer Science & Business Media. This book was released on 2000-12-31 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of an ISSI Workshop, 28 June - 2 July 1999, Bern, Switzerland

Download or read book International Aerospace Abstracts written by and published by . This book was released on 1993 with total page 938 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mechanisms of Chromospheric and Coronal Heating written by Peter Ulmschneider and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 663 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the great problems of astrophysics is the unanswered question about the origin and mechanism of chromospheric and coronal heating. Just how these outer stellar envelopes are heated is of fundamental importance, since all stars have hot chromospheric and coronal shells where the temperature rises to millions of degrees, comparable to the temperatures in the stars' cores. Here for the first time is a comprehensive inventory of the proposed chromospheric and coronal heating theories. The proposed heating processes are critically compared, and the observational evidence for the various mechanisms is reviewed. This is essential reading for all those working in such fields as stellar activity, radio and XUV emission, rotation, and mass loss, for whom a detailed and consistent presentation of our knowledge of chromospheric and coronal heating mechanisms is urgently needed.

Download or read book Physics of Highly Ionized Atoms written by Richard Marrus and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 474 pages. Available in PDF, EPUB and Kindle. Book excerpt: The progress in the physics of highly-ionized atoms since the last NATO sponsored ASI on this subject in 1982 has been enormous. New accelerator facilities capable of extending the range of highly-ionized ions to very high-Z have come on line or are about to be completed. We note particularly the GANIL accelerator in Caen, France, the Michigan State Superconducting Cyclotrons in East Lansing both of which are currently operating and the SIS Accelerator in Darmstadt, FRG which is scheduled to accelerate beam in late 1989. Progress i~ low-energy ion production has been equally dramatic. The Lawrence Livermore Lab EBIT device has produced neon-like gold and there has been continued improvement in ECR and EBIS sources. The scientific developments in this field have kept pace with the technical developments. New theoretical methods for evaluating relativistic and QED effects have made possible highly-precise calcula tions of energy levels in one-and two-electron ions at high-Z. The calculations are based on the MCDF method and the variational method and will be subject to rigorous experimental tests. On the experimental side, precision x-ray and UV measurements have probed the Lamb shift in the one and two electron ions up to Z=36 with increasing precision.

Download or read book Solar Polarization written by K.N. Nagendra and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 553 pages. Available in PDF, EPUB and Kindle. Book excerpt: Novel instruments for high-precision imaging polarimetry have opened new possibilities, including for exploring effects in radiative scattering, atomic physics, spectral line formation, and radiative transfer. This volume gives a comprehensive and up-to-date account of this rapidly evolving and interdisciplinary field of science.

Download or read book Circumstellar Matter written by International Astronomical Union. Symposium and published by Springer. This book was released on 1987-06-30 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the 122nd Symposium of the International Astronomical Union, Heidelberg, Germany, June 23-27, 1986

Download or read book The Theory of Stellar Spectra written by Charles R. Cowley and published by Routledge. This book was released on 1970 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Introduction to Star Formation written by Derek Ward-Thompson and published by Cambridge University Press. This book was released on 2011-02-10 with total page 229 pages. Available in PDF, EPUB and Kindle. Book excerpt: Guiding the reader through all the stages that lead to the formation of a star such as our Sun, this advanced textbook provides students with a complete overview of star formation. It examines the underlying physical processes that govern the evolution from a molecular cloud core to a main-sequence star, and focuses on the formation of solar-mass stars. Each chapter combines theory and observation, helping readers to connect with and understand the theory behind star formation. Beginning with an explanation of the interstellar medium and molecular clouds as sites of star formation, subsequent chapters address the building of typical stars and the formation of high-mass stars, concluding with a discussion of the by-products and consequences of star formation. This is a unique, self-contained text with sufficient background information for self-study, and is ideal for students and professional researchers alike.