Geophysics and Astrophysics Monographs – serie

From the reviews:".....The book is a very good balance between theory and applications, of analysis and synthesis, keeping always the focus on the comprehension of the physics ruling our planetary system.In summary, this represents both an excellent textbook for students and a fundamental reference, and encyclopedic summary current knowledge, for researchers in the Solar System field." (Alessandro Rossi, Celestial Mechanics and Dynamical Astronomy, 2005)

The usual book on the theory of spectral line formation begins with an in-depth dis­ cussion of radiation transfer, including the elegant methods of obtaining analytical solutions for special cases, and of the physics of line broadening. Neither of those features will be found in this book. It is assumed that the reader is already familiar with the essentials of transport theory and of line broadening and is ready to investi­ gate some of the particular applications of the theory to the flow of line photons through the outer layers of a star, or other tenuous media. The main thrust of this book is toward the compilation and presentation of a vast quantity of computational material available to the author in the form of computer output. The material presented represents a highly filtered sample of the published work in this subject plus an extensive set of previously unpublished results. To present large quantities of computer output in an intelligible and efficient way is a difficult task, for which I have found no really satisfactory solution. Chapters III and IV, in particular, contain almost exclusively this type of presentation. The reader may find these chapters somewhat tedious because of the level of condensation of the material. I have tried to reach a reasonable balance between over condensation and excessive detail, which in the long run may be irrelevant.

Studies of the magnetic anomalies paralleling ocean ridges have furnished partisans of continental drift with decisive arguments. To take stock of this important question, my colleague Thellier and I decided in the early summer of 1967 to make it the subject of the annual seminar on Earth physics for the school year 1967-68. Although research was still developing rapidly, the General Assembly of the International Union of Geodesy and Geophysics held in Switzerland in September, particularly some of the meetings in Zurich under the auspices of the International Committee for the Upper Mantle, appeared to confirm that we had made no important omissions. At the con­ clusion of the seminar, where I had been responsible for most of the lectures, I resolved to write the present volume for the non-specialized scientific reader. The project turned out to be a good deal more ambitious than I had thought. It is quite an undertaking nowadays to try to survey a rapidly growing subject, first of all because of the difficulty of gathering material; publication delays are now nearing one year, with the result that specialists communicate largely through a selective distribution of reports, as well as verbally in frequent colloquia. I warmly thank those who helped me in getting unpublished literature, especially Xavier Le Pichon. Even so, some essential work came to my knowledge only lately.

Studies of the magnetic anomalies paralleling ocean ridges have furnished partisans of continental drift with decisive arguments. To take stock of this important question, my colleague Thellier and I decided in the early summer of 1967 to make it the subject of the annual seminar on Earth physics for the school year 1967-68. Although research was still developing rapidly, the General Assembly of the International Union of Geodesy and Geophysics held in Switzerland in September, particularly some of the meetings in Zurich under the auspices of the International Committee for the Upper Mantle, appeared to confirm that we had made no important omissions. At the con­ clusion of the seminar, where I had been responsible for most of the lectures, I resolved to write the present volume for the non-specialized scientific reader. The project turned out to be a good deal more ambitious than I had thought. It is quite an undertaking nowadays to try to survey a rapidly growing subject, first of all because of the difficulty of gathering material; publication delays are now nearing one year, with the result that specialists communicate largely through a selective distribution of reports, as well as verbally in frequent colloquia. I warmly thank those who helped me in getting unpublished literature, especially Xavier Le Pichon. Even so, some essential work came to my knowledge only lately.

The usual book on the theory of spectral line formation begins with an in-depth dis­ cussion of radiation transfer, including the elegant methods of obtaining analytical solutions for special cases, and of the physics of line broadening. Neither of those features will be found in this book. It is assumed that the reader is already familiar with the essentials of transport theory and of line broadening and is ready to investi­ gate some of the particular applications of the theory to the flow of line photons through the outer layers of a star, or other tenuous media. The main thrust of this book is toward the compilation and presentation of a vast quantity of computational material available to the author in the form of computer output. The material presented represents a highly filtered sample of the published work in this subject plus an extensive set of previously unpublished results. To present large quantities of computer output in an intelligible and efficient way is a difficult task, for which I have found no really satisfactory solution. Chapters III and IV, in particular, contain almost exclusively this type of presentation. The reader may find these chapters somewhat tedious because of the level of condensation of the material. I have tried to reach a reasonable balance between over condensation and excessive detail, which in the long run may be irrelevant.

The rather excessive public preoccupation of the immediate past with what has been labeled the 'environmental crisis' is now fortunately being replaced by a more sus­ tained and rational concern with pollution problems by public administrators, engineers, and scientists. It is to be expected that members of the engineering profes­ sion will in the future widely be called upon to design disposal systems for gaseous and liquid wastes which meet strict pollution control regulations and to advise on possible improvements to existing systems of this kind. The engineering decisions involved will have to be based on reasonably accurate quantitative predictions of the effects of pollutants introduced into the atmosphere, ocean, lakes and rivers. A key input for such calculations comes from the theory of turbulent diffusion, which enables the prediction of the concentrations in which pollutants may be found in the neighborhood of a release duct, such as a chimney or a sewage outfall. Indeed the role of diffusion theory in pollution prediction may be likened to the role of applied mechanics (,strength of materials') in the design of structures for adequate strength. At least a certain group of engineers will have to be proficient in applying this particular branch of science to practical problems. At present, training in the theory of turbulent diffusion is available only at the gra­ duate level and then only in a very few places.

Over the past two decades auroral science has developed from a somewhat mysterious and imprecise specialty into a discipline central in the study of the ionosphere and magnetosphere. The investigation of aurora unites scientists with very different backgrounds and interests so that it is difficult to write a self-contained account of the field in a book of reasonable length. In this work I have attempted to include those aspects of theory which I have found valuable in predicting the effects on the atmosphere of auroral particle precipitation. In addition I have attempted to describe the techniques of observation with particular emphasis on optical methods which have been useful. While the aeronomy of aurora has been regarded as central, the mechanisms by which particles are accelerated and precipitated into the atmosphere is of no less interest. This aspect of the subject has however been treated in a briefer fashion since it is a part of the immense and rapidly developing field of magnetospheric science. Generally I have attempted to provide a coherent introduction to auroral science with an emphasis on relatively simple physical interpretations and models. References are given to enable the reader to find more extensive or rigorous discussions of particular topics. A fairly complete, quantitative atlas of the auroral spectrum is included.

Over the past two decades auroral science has developed from a somewhat mysterious and imprecise specialty into a discipline central in the study of the ionosphere and magnetosphere. The investigation of aurora unites scientists with very different backgrounds and interests so that it is difficult to write a self-contained account of the field in a book of reasonable length. In this work I have attempted to include those aspects of theory which I have found valuable in predicting the effects on the atmosphere of auroral particle precipitation. In addition I have attempted to describe the techniques of observation with particular emphasis on optical methods which have been useful. While the aeronomy of aurora has been regarded as central, the mechanisms by which particles are accelerated and precipitated into the atmosphere is of no less interest. This aspect of the subject has however been treated in a briefer fashion since it is a part of the immense and rapidly developing field of magnetospheric science. Generally I have attempted to provide a coherent introduction to auroral science with an emphasis on relatively simple physical interpretations and models. References are given to enable the reader to find more extensive or rigorous discussions of particular topics. A fairly complete, quantitative atlas of the auroral spectrum is included.

The aim of the present book will be to summarize the results of the space exploration of the Moon in the past fifteen years -culminating in the manned Apollo missions of 1969-1972 -on the background of our previous acquaintance with our satellite made in the past by astronomical observations at a distance. Astronomy is one of the oldest branches of science conceived by the inquisitive human mind; though until quite recently it had been debarred from the status of a genuine experimental science by the remoteness of the objects of its study. With the sole exception of meteoritic matter which occasionally finds its way into our labora­ tories, all celestial bodies could be investigated only at a distance: namely, from the effects of attraction exerted by their mass, or from the ciphered messages of their light carried by nimble-footed photons across the intervening gaps of space. A dramatic emergence oflong-range spacecraft -capable of carrying men with their instruments not only outside the confines of our atmosphere, but to the actual surface of our nearest celestial neighbour - has since 1957 thoroughly changed this time­ honoured picture. In particular (as we shall detail in Chapter 1 of this book) space astronomy ofthe Moon is barely 15 years old. But relative infant as it is by age, it has already provided us with such a tremendous amount of new and previously inacces­ sible scientific data as to virtually revolutionalize our subject.

o beaute sans seconde SeuIe sembIabIe Ii toi SOLEIL pour tout Ie monde ... JEAN-FRANc;OIS SARASIN (1615-1654) The last decade has seen the publication of monographs covering most areas of solar activity: flares (Smith and Smith, 1963), sunspots (Bray and Loughhead, 1964) and the corona (Billings, 1966). Consequently, of all the major manifestations of solar activity only prominences are without a comprehensive and unified treatment in the current literature. The present book is written in an attempt to remedy this situation, and to furnish an account of some of the most spectacular and most beautiful aspects of solar activity. Our ultimate aim is an understanding of the physical processes involved. I hope that this book may provide if only a small step toward this goal. After an historical introduction and some general definitions Chapter I proceeds with an account of several classification schemes for prominences. Most of the observational material is presented in Chapter II and forms the basis on which different models of prominences are built in Chapter III. Chapters IV and V give most of the physics of prominences, treating, as they do, the formation and stability of these objects. The interaction of prominences with other manifestations of solar activity is the subject of Chapter VI, and the final Chapter VII considers prominences in the larger context: as an integral part of the corona.

TO GEOCHEMISTRY by CLAUDE-JEAN ALLEGRE Department of Earth Sciences, University of Paris 7 and GIL MICHARD Department of Chemistry, University of Paris 7 D, REIDEL PUBLISHING COMPANY DORDRECHT-HOLLAND / BOSTON-U. S. A. INTRODUCTION A LA GEOCHIMIE First published by Presses Universitaires de France, Paris, 1973 Translated/rom the French by Robert N. Varney Library of Congress Catalog Card Number 74-83871 e-ISBN -13: 978-94 -010-2261-3 ISBN -13: 978-90-277-0498-6 DOl: 10. 1007/978-94-010-2261-3 Published by D. Reidel Publishing Company, P. O. Box 17, Dordrecht, Holland Sold and distributed in the U. S. A. , Canada, and Mexico by D. Reidel Publishing Company, Inc. 306 Dartmouth Street, Boston, Mass. 02116, U. S. A. All Rights Reserved Copyright © 1974 by D. Reidel Publishing Company, Dordrecht, Holland No part of this book may be reproduced in any form, by print, photoprint, microfilm, or any other means, without written permission from the publisher TABLE OF CONTENTS PREFACE IX PREFACE BY THE TRANSLATOR XI CHAPTER 1 / THE EARTH AS A CHEMICAL SYSTEM 1 1. 1. The Earth within the Solar System 1 1. 2. The Scale of Time 1 1. 3. The Overall Chemical Composition of the Earth, the Solar System, and the Universe 2 1. 4. Chemical Compounds in the Solar System: Cosmological Minerals 5 1. 4. 1. Simple Molecules 6 1. 4. 2. Simple Solids 6 1. 4. 3. Silicates 6 1. 4. 4. Carbon Polymers 6 1. 4. 5. Fe-Ni Alloys 6 1. 5.

TO GEOCHEMISTRY by CLAUDE-JEAN ALLEGRE Department of Earth Sciences, University of Paris 7 and GIL MICHARD Department of Chemistry, University of Paris 7 D, REIDEL PUBLISHING COMPANY DORDRECHT-HOLLAND / BOSTON-U. S. A. INTRODUCTION A LA GEOCHIMIE First published by Presses Universitaires de France, Paris, 1973 Translated/rom the French by Robert N. Varney Library of Congress Catalog Card Number 74-83871 e-ISBN -13: 978-94 -010-2261-3 ISBN -13: 978-90-277-0498-6 DOl: 10. 1007/978-94-010-2261-3 Published by D. Reidel Publishing Company, P. O. Box 17, Dordrecht, Holland Sold and distributed in the U. S. A. , Canada, and Mexico by D. Reidel Publishing Company, Inc. 306 Dartmouth Street, Boston, Mass. 02116, U. S. A. All Rights Reserved Copyright © 1974 by D. Reidel Publishing Company, Dordrecht, Holland No part of this book may be reproduced in any form, by print, photoprint, microfilm, or any other means, without written permission from the publisher TABLE OF CONTENTS PREFACE IX PREFACE BY THE TRANSLATOR XI CHAPTER 1 / THE EARTH AS A CHEMICAL SYSTEM 1 1. 1. The Earth within the Solar System 1 1. 2. The Scale of Time 1 1. 3. The Overall Chemical Composition of the Earth, the Solar System, and the Universe 2 1. 4. Chemical Compounds in the Solar System: Cosmological Minerals 5 1. 4. 1. Simple Molecules 6 1. 4. 2. Simple Solids 6 1. 4. 3. Silicates 6 1. 4. 4. Carbon Polymers 6 1. 4. 5. Fe-Ni Alloys 6 1. 5.

If our eyes were radio rather than optical wide-band detectors it is well known that for us the brightest object in the sky would still be the Sun; that planets, stars and the Milky Way would still shine feebly (and that we would still occasionally be blinded by man-made sources). What is less well known is that quite a different earthbound overcast would hover about us, with its climatic zones, its seasonal changes, its unpredictable storms and scintillating transparence. To be sure, we can get a sort of glimpse of this peculiar type of weather when we tune our receiver to radio broad­ casting from some remote spot, or photograph the Earth from space at certain specific wavelengths. Nevertheless no one has ever looked at the ionized shroud of the Earth without the help of sophisticated apparatus, and this is one of the reasons why in this domain the phenomena are not easily abstracted from the use of specific techniques. For generations, the study of the ionosphere has been deeply interwoven with the practice of radio communication and detection. Today however, ionospheric physics is best thought of as a branch of space physics; that part of physics which deals with processes at work in the solar system and methods developed for its exploration.

This monograph is based on four papers which have been published in Astrophysics and Space Sciences 1970--1974. They contain the results of our joint work started in 1968 at the University of California, San Diego, in La Jolla. The work was based on the belief that the complicated processes by which our solar system was formed can only be clarified by close collaboration between representatives of the physical and chemical sciences. Our investigations have also been strongly supported by work at other institu­ tions, especially by a group at the Royal Institute of Technology, Stockholm, where a number of plasma experiments have been made in order to clarify basic processes which are relevant to cosmogonic problems. These experiments were, in their turn inspired by theoretical work on primordial processes carried out during the last thirty-five years. We especially want to acknowledge the contributions by Drs N. Herlofson, B. Lehnert, C.-G. Fiilthammar, and Lars Danielsson in Stockholm and by Drs J.

This book is the first part of the originally planned publication by Z. Svestka and L. D. de Feiter 'Solar High Energy Photon and Particle Emission'. The second part, with the original title, was to be published by de Feiter in about one year from now. However, to the deep sorrow of all of us, Dr de Feiter died suddenly and unexpectedly when the present book was in print. Thus, unfortunately, de Feiter's second part may not appear. Due to the fact that the originally planned publication was divided into two parts, the present book is mainly descriptive and concerned with the flare morphology. It was expected that theoretical interpretations would be extensively developed in the second part, prepared by de Feiter. In particular, this refers to the theoretical back­ grounds of radio emissions, particle acceleration and particle propagation in space. Only in Chapter II, concerning the 'low-temperature' flare, do we go deeper into the theoretical interpretations, anticipating that de Feiter would have been concerned mainly with the 'high-energy' physics. Still, the book includes discussions on all important aspects of flares and thus can present the reader with a complete picture of the complex flare phenomenon. It is clear that many observed data on flares can be interpreted in different ways.

Only a few positive experimental results have been reported, in spite of an expenditure of considerable effort by many people: in particular, the possible Galactic Center emission line (473 to 530keV) and 'Y-ray lines at several energies (e.

Double and multiple stars are the rule in the stellar population, and single stars the minority, as the abundance of binary systems in the space surrounding the sun shows beyond doubt.

Double and multiple stars are the rule in the stellar population, and single stars the minority, as the abundance of binary systems in the space surrounding the sun shows beyond doubt. Numerous stellar features, and methods of their exploration, ensue specifically from the one but widespread property, the binary nature. Stellar masses are basic quantities for the theory of stellar structure and evolution, and they are ob­ tained from binary-star orbits where they depend on the cube of observed parameters; this fact illustrates the significance of orbits as well as the accuracy requirements. Useful in dating stellar history is the knowledge that components of a system, different though they may appear, are of the same origin and age. Between star formation and the genesis of binaries a direct connection can be traced. The later stages of stellar life branch into a great variety as mutual influence between the components of a close binary pair develops. Transfer and exchange of mass and the presence of angular momentum in the orbit give rise to special tracks of evolution, not found for single stars, and to peculiar spectral groups. This is not a new story but it has a new ending: The patterns of evolution involving mass transfer appear to lead ultimately to single objects.

Short History of Solar Radio Astronomy Since its birth in the forties of our century, solar radio astronomy has grown into an extensive scientific branch comprising a number of quite different topics covering technical sciences, astrophysics, plasma physics, solar-terrestrial physics, and other disciplines.

1. 1. Short History of Solar Radio Astronomy Since its birth in the forties of our century, solar radio astronomy has grown into an extensive scientific branch comprising a number of quite different topics covering technical sciences, astrophysics, plasma physics, solar-terrestrial physics, and other disciplines. Historically, the story of radio astronomy goes back to the times of James Clerk Maxwell, whose well known phenomenological electromagnetic field equations have become the basis of present-time radio physics. As a direct consequence of these equations, Maxwell was able to prognosticate the existence of radio waves which fifteen years later were experimentally detected by the famous work of Heinrich Hertz (1887/88). However, all attempts to detect radio waves from cosmic objects failed until 1932, which was mainly due to the early stage of development of receiving techniques and the as yet missing knowledge of the existence of a screening ionosphere (which was detected in 1925). Therefore, famous inventors like Thomas Edison and A. E. Kennelly, as well as Sir Oliver Lodge, were unsuccessful in receiving any radio emission from the Sun or other extraterrestrial sources. Another hindering point was that nobody could a priori expect that solar radio emission should have something to do with solar activity so that unfortunately by chance some experiments were carried out just at periods of low solar activity. This was also why Karl Guthe Jansky at the birth of radio astronomy detected galactic radio waves but no emission from the Sun.

The purpose of this textbook is to provide a basic knowledge of the main parts of modern astrophysics for all those starting their studies in this field at the undergraduate level. The reader is supposed to have only a high school training in physics and mathematics. In many respects this Introduction to Advanced Astrophysics could represent a volume of the Berkeley Physics Course. Thus, the primary audience for this work is composed of students in astronomy, physics, mathematics, physical chemistry and engineering. It also includes high school teachers of physics and mathematics. Many amateur astronomers will fmd it quite accessible. In the frame of approximations proper to an introductory textbook, the treatment is quite rigorous. Therefore, it is also expected to provide a firm background for a study of advanced astrophysics on a postgraduate level. A rather severe selection is made here among various aspects of the Universe accessible to modern astronomy. This allows us to go beyond simple information on astronomical phenomena - to be found in popular books - and to insist upon explanations based on modern general physical theories. More precisely, our selection of topics is determined by the following considerations: The study of the solar system (the Moon and the planets) has recently progressed at a tremendous rate. However, the very rich harvest of observations provided by space research is mainly purely descriptive and is perfectly presented in review papers of Scien­ tific American, Science, Physics Today and similar magazines.

TO NUCLEAR ASTROPHYSICS The Formation and the Evolution of Matter in the Universe JEAN AUDOUZE lnstitut d'Astrophysique de Paris, France and SYLVIE VA UCLAI R DAPHE, Ohservatoire de Meudon, France and lnstitut d'Astrophysique, Paris D, REIDEL PUBLISHING COMPANY DORDRECHT: HOLLAND/BOSTON: U. S. A. LONDON: ENGLAND Library of Congre~ Cataloging in Publication Data Audouzc. Jean An introduction to nuclear astrophysics. (Geophysics and astrophysics monographs; v. 18) En!. and updated translation of L'Astrophysique nuclt\aire. Includes bibliographies and index. \. Nuclear astrophysics. I. Vauclair, Sylvie, joint author. II. Title. III. Series. QB464. A9313 1979 523. 01'9'7 79-20752 ISBN-13: 978-90-277-1053-6 e-ISBN-13: 978-94-009-9477-5 DO I: 10. 1007/978-94-009-9477-5 Published by D. Reidel Publishing Company, P. O. Box 17. Dordrecht, Holland Sold and distributed in the U. S. A. , Canada, and Mexico by D. Reidel Publishing Company, Inc. Lincoln Building. 160 Old Derby Street, Hingham, Mass. 02043, U. S. A. All Rights Reserved Copyright © 1980 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint of the hardcover 1st edition 1980 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner TABLE OF CONTENTS IX FOREWORD INTRODUCTION xi XXI ACKNOWLEDGEMENTS CHAPTER I / THE OBSERVATIONAL BASIS OF NUCLEAR ASTROPHYSICS 1. 1. The Importance of the Four Fundamental Interactions 1 1. 2.

TO NUCLEAR ASTROPHYSICS The Formation and the Evolution of Matter in the Universe JEAN AUDOUZE lnstitut d'Astrophysique de Paris, France and SYLVIE VA UCLAI R DAPHE, Ohservatoire de Meudon, France and lnstitut d'Astrophysique, Paris D, REIDEL PUBLISHING COMPANY DORDRECHT: HOLLAND/BOSTON: U. S. A. LONDON: ENGLAND Library of Congre~ Cataloging in Publication Data Audouzc. Jean An introduction to nuclear astrophysics. (Geophysics and astrophysics monographs; v. 18) En!. and updated translation of L'Astrophysique nuclt\aire. Includes bibliographies and index. \. Nuclear astrophysics. I. Vauclair, Sylvie, joint author. II. Title. III. Series. QB464. A9313 1979 523. 01'9'7 79-20752 ISBN-13: 978-90-277-1053-6 e-ISBN-13: 978-94-009-9477-5 DO I: 10. 1007/978-94-009-9477-5 Published by D. Reidel Publishing Company, P. O. Box 17. Dordrecht, Holland Sold and distributed in the U. S. A. , Canada, and Mexico by D. Reidel Publishing Company, Inc. Lincoln Building. 160 Old Derby Street, Hingham, Mass. 02043, U. S. A. All Rights Reserved Copyright © 1980 by D. Reidel Publishing Company, Dordrecht, Holland Softcover reprint of the hardcover 1st edition 1980 No part of the material protected by this copyright notice may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording or by any informational storage and retrieval system, without written permission from the copyright owner TABLE OF CONTENTS IX FOREWORD INTRODUCTION xi XXI ACKNOWLEDGEMENTS CHAPTER I / THE OBSERVATIONAL BASIS OF NUCLEAR ASTROPHYSICS 1. 1. The Importance of the Four Fundamental Interactions 1 1. 2.

No part of the Hertzsprung-Russell diagram shows a more pronounced diversity of stellar types than the upper part, which contains the most luminous stars. Can one visualize a larger difference than between a luminous, young and extremely hot Of star, and a cool, evolved pulsating giant of the Mira type, or an S-type supergiant, or - again at the other side of the diagram - the compact nucleus of a planetary nebula? But there is order and unity in this apparent disorder! Virtually all types of bright stars are evolutionally related, in one way or the other. Evolution links bright stars. In many cases the evolution is speeded up by, or at least intimately related to various signs of stellar instability. Bright stars lose mass, either continuously or in dramatic sudden events, they vibrate or pulsate - and with these tenuous, gigantic objects this often happens in a most bizarre fashion. Sometimes the evolution goes so fast that fundamental changes are observable in the time span of a human's life - several of such cases have now been identified.

The thermodynamics of the atmosphere is the subject of severai chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fiII this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can play a role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the urst four chapters), they are only briefly discussed, and emphasis is laid on those topics that wilI be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics ofirreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a rigorous formulation of the thermodynamic functions of c10uds (exclusive of any consideration of microphysical effects) and a better understanding of the approx­ imations usually implicit in practical applications.

The thermodynamics of the atmosphere is the subject of severai chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fiII this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can play a role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the urst four chapters), they are only briefly discussed, and emphasis is laid on those topics that wilI be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics ofirreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a rigorous formulation of the thermodynamic functions of c10uds (exclusive of any consideration of microphysical effects) and a better understanding of the approx­ imations usually implicit in practical applications.

This book is an outgrowth of the notes made for the semester lectures on 'Problems of Extragalactic Astronomy' given almost annually during two decades at the Ob- servatorio Astronomico of the Universidad de Cordoba. Shorter versions were also given at La Plata, Santiago de Chile, Sao Paulo, Rio de Janeiro and Paraiba. E. Scalise made a Portuguese language version of the notes and encouraged me to publish them; although my friend J. Kleczek is to be blamed for the idea of this book. Not every subject on Extragalactic Astronomy has been touched in this book: instead I have followed those which interested me during 25 years of professional practice in this part of the world. I acknowledge helpful suggestions from M. Pastoriza and G. Carranza, the com- prehension of Director L. Milone, and the collaboration of the staff of the Observa- tory in Cordoba. R. Tschamler's humor and wit made light the task of producing the English version and M. Pizarro's devotedness produced the edited MS. To both of them I am in deep gratitude. "A book is published out of necessity, otherwise the author would spend his entire life polishing the originals" was the answer given by J. L.Borges to an inquisi- tive journalist. These words explain why this book is so different from the lecture notes, and also from the book I was hoping for. I thank B. McCormac and the D. Reidel Publ. Co. for my salvation from Borges' inferno.