Radio Recombination Lines

Author: Mark Gordon
Publisher: Springer Science & Business Media
ISBN: 9401002614
Format: PDF, ePub
Download Now
Recombination lines at radio wavelengths have been - and still are - a pow erful tool for modern astronomy. For more than thirty years they have allowed astronomers to probe the gases from which stars form. They have even been detected in the Sun. In addition, observations of these spectral lines facilitate basic research into the atom, in forms and environments that can only exist in the huge dimensions and extreme conditions of cosmic laboratories. We intend this book to serve as a tourist's guide to the world of Radio Recombination Lines. It contains three divisions: a history of their discovery, the physics of how they form and how their voyage to us influences their spectral profiles, and a description of their many astronomical contributions to date. The appendix includes supplementary calculations that may be useful to some astronomers. This material also includes tables of line frequencies from 12 MHz to 30THz (AlOJLm) as well as FORTRAN computer code to calculate the fine structure components of the lines, to evaluate radial matrix integrals, and to calculate the departure coefficients of hydrogen in a cosmic environment. It also describes how to convert observational to astrophysical units. The text includes extensive references to the literature to assist readers who want more details.

Tools of Radio Astronomy

Author: Kristen Rohlfs
Publisher: Springer Science & Business Media
ISBN: 3662053942
Format: PDF, ePub, Docs
Download Now
1. Most authoritative and established of graduate-level textbooks and references in the field. 2. Provides not only specialists with the details they need but also non-specialists with access to the jargon and basics of this vital field. 3. New edition offers completely rewritten chaptes on interferometry and aperture synthsis, as well as thoroughly revised chapters on receiver technology and interstellar molecules. 4. From the reviews of previous editions: "Nowadays Rohlfs and Wilson`s Tools of Radio Astronomy is the inevitable reference book. This is the one book you should buy if you want to become a radio astronomer. " The Observatory, 2001 "An excellent survey of the tools a radio astronomer needs to pursue the trade... The neatly encapsulated derivations of many classical relations will make the book useful to lecturer and student and practicing astronomer alike." American Scientist "People use this book so much because it describes what one needs in order to actually do radio astronomy... This book is an excellent graduate level text - the best available by far. It is also the best reference book for practicing astronomers who want to do radio astronomy properly, to interpret jargon or to understand some of the details of the literature." Physics Today

On the Formation of the Most Massive Stars in the Galaxy

Author: Roberto J. Galván-Madrid
Publisher: Springer Science & Business Media
ISBN: 1461433088
Format: PDF, Docs
Download Now
The most massive stars in the galaxy - those with more than 15 to 20 solar masses - are lilkely to ionize their surroundings before they reach their final mass. How can they accrete in spite of the presence of over-pressurized gas? This thesis presents results of Submillimeter Array (SMA) and Very Large Array (VLA) studies of massive star formation regions in the early stages of ionization, as well as an analysis of numerical simulations of the evolution of these young HII regions. The results favor a picture in which very massive stars form in accretion flows that are partially ionized and that keep accreting material from their environment.

Secular Evolution of Galaxies

Author: Jesús Falcón-Barroso
Publisher: Cambridge University Press
ISBN: 1107035279
Format: PDF, ePub, Mobi
Download Now
Graduate-level text on galaxy evolution, one of the most popular research topics in astrophysics, with chapters contributed by leading astronomers.

Radio Recombination Lines

Author: P.A. Shaver
Publisher: Springer
ISBN: 9027711038
Format: PDF, Mobi
Download Now
Since their first detection 15 years ago, radio recombination lines from several elements have been observed in a wide variety of objects including HII regions, planetary nebulae, molecular clouds, the diffuse interstellar medium, and recently, other galaxies. The observations span almost the entire range from 0.1 to 100 GHz, and employ both single djsh and aperture synthesis techniques. The theory of radio recombination lines has also advanced strongly, to the point where it is perhaps one of the best-understood in astro physics. In a parallel development, it has become possible over the last decade to study these same highly-excited atoms in the laboratory; this work provides further confirmation of the theoretical framework. However there has been continuing controversy over the astrophysical interpre tation of radio recombination line observations, especially regarding the role of stimulated emission. A workshop was held in Ottawa on 24-25 August, 1979, bringing together many of the active scientists to review the field and discuss these questions of interpretation. A broad concensus has emerged: the subtleties of the line-formation process are understood, and the conditions under which reliable in formation can easily be extracted from the line measurements are known. It thus appears likely that the emphasis will shift increasingly from the study of the line phenomenon itself to further application in other areas of astrophysics, ranging from physical processes in plasmas (temperatures, densities, ionization structure), to the large-scale properties of our galaxy (abundances, kinematics, structure), and studies of extragalactic systems.