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Quasars and active galaxies are the most powerful emitters of radiation in the universe. Modern radio telescope arrays have shown that the ultimate energy source resides in the central few parsecs of the galactic nucleus, and powers the emitting regions by way of two oppositely-directed relativistic jets of energy. This volume presents the latest observations and theories of these remarkable objects. Topics discussed include superluminal motions, the physics of jets and shock fronts in jets, related optical observations, and cosmic evolution. Particular attention is given to the "unified theories," which attempt to show that many of the phenomena in powerful extragalactic objects are different aspects of a single, basic mechanism; the main difference in their appearance is a result of their different orientation with respect to the observer.
A masterly survey of the last 13 years of Very Long Baseline Interferometry, reviewed in light of the most advanced astronomical observations. Topics covered include: Nonthermal emission from extragalactic radio sources; Principles of synchrotron emission in relation to astrophysics; Theory of relativistic jets; Young, powerful radio sources and their evolution; Scintillation in extragalactic radio sources; Radio and optical interferometry; Radio polarimetry; Unified schemes; Deep fields; Tropospheric and ionospheric phase calibration; Supernovae; VLBI for geodesy and geodynamics.
337 F(e) = (z) where the angle between the directions III and 112 is equal to 8. r is the angular diameter effective distance of the epoch for recombination. F (8) ~ve have F(e) : f (e) ~ (S" ) e. . ~ is a Bessel function. It is assumed here that the spectrum of gravitational waves takes the form 1\ hI'::: hoK for all relevant wavelengths, a is beam width of the radio antenna, d\= d~, and ~ is the duration of the process of recombinations in \-time. The results for different beam widths are shown in Fig. 1. 338 I. D. NOVIKOV 1-. . . -__ 0. 5 1 1. 5 2 e' 0. 5 o and for a l' (solid line) and Fig. 1. The function f(8) for n for a = 2' (dotted line). These formula should be used in analysing the implications of future observations. Comparison with the observational data now available enables us to establish an upper limit for the energy density of long gravitational waves. This method is most sensitive for gravitational waves with A ~ ct The fluctuations ~; due to these waves have scale ~ 0. 03 GW rec 4 radian. If, according to modern observations, we take ~;
Professor Zdenek Kopal is sixty-seven this year even though his scientific activity, enthusiasm and springy step hardly betray the ad vancement in years. He carne to Manchester as Professor of Astronomy thirty years ago after a very fruitful association of fourteen years with the Harvard Observatory. Much impressed with the young man, Harlow Shapley, who with characteristic insight had recognised in Kopal the qualities that have since made him an outstanding leader in ec1ipsing binary research, had invited him over as a Research Associate. In the subsequent decade Kopal set about the task of introducing analytical rigour in the solution of orbit al elements that hitherto had depended ex c1us...
I.A.U. symposium No. 110 on VLBI and Compact Radio Sources was held in Bologna, Italy from June 27 to July 1, 1983. 166 participants from 19 countries were registered and 106 invited and contributed papers were registered. The scientific presentations and discussion concentrated on VLBI observation and interpretation of galactic and extragalactic radio sour ces, including topics as diverse as quasars and galactic nuclei, inter stellar masers, pulsars, and astrometry. Geodetic applications and tech nical development were treated only briefly, as these topics have been the subject of other recent international symposia. Since the first VLBI observations in 1967, sensitivity, resolution, and im...
IAU Symposium 97, Extragalactic Radio Sources, was held at Albuquerque, New Mexico August 3-7, 1981. It was co-sponsored by IAU Commissions 28, 40, 47 and 48 and by URSI Commission J. Financial and organizational support were provided by the National Radio Astronomy Observatory, the University of New Mexico, and the National Science Foundation. A wide variety of interesting objects and phenomena can be covered under the heading "Extragalactic Radio Sources", and a diverse set of topics was in fact discussed at the symposium. Radio galaxies, quasars, Seyfert galaxies and BL Lacertids received the most attention, but normal galaxies, the galactic center, and even SS433 were also discussed. While the unifying theme of the symposium was radio emission, studies at all wavelengths--X-ray, UV, optical, IR, and radio--were included. In general, the emphasis was on individual objects and the physical processes associated with them, but there were also papers on statistical studies and cosmology. The symposium was attended by 209 scientists from 18 countries.
Attilio Ferrari I want to recall here the basic points I raised at the beginning of the Workshop as the main targets of discussion (in the name of the Scientific Committee). I attempted to focus the attention of participants on the fact that, in many instances, we tend to discuss jets in terms of simple physics, more or less as one did at the time extragalactic radio sources were discovered: for instance, we still use equipartition arguments. However, we must realize that processes in jets, leading to their morphologies and energetics clearly depend on complex plasma phenomena. Therefore, the same standard arguments used to derive characteristic parameters should be questioned; some of the s...
This book provides a comprehensive survey of modern molecular astrophysics. It includes an introduction to molecular spectroscopy and then addresses the main areas of current molecular astrophysics, including galaxy formation, star forming regions, mass loss from young as well as highly evolved stars and supernovae, starburst galaxies plus the tori and discs near the central engines of active galactic nuclei. All chapters have been written by invited authors who are acknowledged experts in their fields. The thorough editorial process has ensured a uniformly high standard of exposition and a coherent style. The book is unique in giving a detailed view of its wide-ranging subject. It will provide the standard introduction for research students in molecular astrophysics. The book will be read by research astronomers and astrophysicists who wish to broaden the basis of their knowledge or are moving their activities into this burgeoning field. It will enable chemists to learn the astrophysics most related to chemistry as well as instruct physicists about the molecular processes most important in astronomy.