Fundamental Astronomy. Springer-Verlag Berlin Heidelberg GmbH

Transcription

1 Fundamental Astronomy Springer-Verlag Berlin Heidelberg GmbH

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3 H. Karttunen P. Kroger H. Oja M. Poutanen K. J. Donner (Eds.) Fundamental Astronomy Third Revised and Enlarged Edition With 402 Illustrations Including 36 Colour Plates Springer

4 Dr. Hannu Karttunen Tuorla Observatory, University of Turku, FIN Piikko, Finland Dr. Pekka Kroger Isonniitynkatu 9 C9, FIN Helsinki, Finland Dr. Markku Poutanen Finnish Geodetic Institute, Geodeetinrinne 2, FIN Masala, Finland Dr. Karl Johan Donner Observatory, P.O. Box 14, FIN University of Helsinki, Finland Dr. Heikki Oja Observatory, P.O. Box 14, FIN University of Helsinki, Finland Cover photograph: The 15-m SEST (Swedish-ESO Submillimetre Telescope) at La Silla, Chile. (Photograph European Southern Observatory) Frontispiece: The 1/ Carinae nebula, NGC3372, is a giant HII region in the Carina spiral arm of our galaxy at a distance of 8000 light-years. (Photograph European Southern Observatory) Title of the original Finnish edition: Tiihtitieteen perusteet (Ursan julkaisuja 56) Tăhtitieteellinen yhdistys Ursa, Helsinki 1984, 1995 Sources for the illustrations are given in the captions and more fully at the end of the book. Most of the uncredited illustrations are Ursa Astronomical Association, Raatimiehenkatu 3A2, FIN Helsinki, Finland ISBN ISBN (ebook) DOI / Library of Congress Cataloging-in-Publication Data. Tăhtitieteen perusteet. English. Fundamental astronomy 1 H. Karttunen... [et al.] eds. - 3rd rev. and enl. ed. p. cm. Includes bibliographical references and index. ISBN (softcover :alk. paper) 1. Astronomy.1. Karttunen, Hannu. II. Title QB43.2. T This work is subject to copyright. AII rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9,1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. Springer-Verlag Berlin Heidelberg 1987, 1994, 1996 OriginaIly published by Springer-Verlag Berlin Heidelberg New York in1996 The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence 01 a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for generaf use. Production editor: A. Kiibler, Heidelberg Cover design: E. Kirchner, Heidelberg Typesetting: K + V Fotosatz GmbH, D Beerfelden SPIN: / Printed on acid-free paper

5 Preface to the Third Edition In addition to small corrections and notes on new results this third edition includes two major revisions. Development of telescopes and instruments has been fast, and the chapter on observations and instruments was getting out of date. Material on the CCD camera has been added; the text in the section on future telescopes has been updated and included in other sections, since most of the telescopes have already been built. The chapter on galaxies has been reorganized to reflect the physical properties instead of morphological classification. We are grateful to our keen readers who have sent us comments even on minute typographical errors found in the previous edition. Helsinki, June 1996 The Editors

6 Preface to the Second Edition For this second English edition, the text was brought up to date to correspond to the situation as of April Small revisions were made throughout the book, and some sections in Chapters 3 (Observations and Instruments), 8 (The Solar System), 13 (The Sun), and 18 (The Milky Way) were rewritten. Many new photographs were added, some of them as replacements for older ones. In many reviews of this book's English as well as German first editions, more exercises were expected at the ends of the chapters. We have added worked-out examples to nearly all chapters that didn't have them before, and we added some homework problems to the chapters too. The answers to these problems are to be found at the end of the Appendices. We hope the new examples and problems facilitate the work of the instructor who may choose to use this book. We want to thank Dr. Christian Naundorf of Bonn, Drs. Erik Heyn Olsen and J. O. Petersen of Copenhagen, Dr. Bjorn Sundelius of Goteborg, and an anonymous German book buyer, who pointed out many typographical errors and inaccuracies in our book. For financial support in modifying the second English edition, we thank Suomalaisen kirjallisuuden edisuimisvarojen valtuuskunta. Helsinki, October 1993 The Editors

7 Preface to the First Edition The main purpose of this book is to serve as a university textbook for a first course in astronomy. However, we believe that the audience will also include many serious amateurs, who often find the popular texts too trivial. The lack of a good handbook for amateurs has become a problem lately, as more and more people are buying personal computers and need exact, but comprehensible, mathematical formalism for their programs. The reader of this book is assumed to have only a standard high-school knowledge of mathematics and physics (as they are taught in Finland); everything more advanced is usually derived step by step from simple basic principles. The mathematical background needed includes plane trigonometry, basic differential and integral calculus, and (only in the chapter dealing with celestial mechanics) some vector calculus. Some mathematical concepts the reader may not be familiar with are briefly explained in the appendices or can be understood by studying the numerous exercises and examples. However, most of the book can be read with very little knowledge of mathematics, and even if the reader skips the mathematically more involved sections, (s)he should get a good overview of the field of astronomy. This book has evolved in the course of many years and through the work of several authors and editors. The first version consisted of lecture notes by one of the editors (Oja). These were later modified and augmented by the other editors and authors. Hannu Karttunen wrote the chapters on spherical astronomy and celestial mechanics; Vilppu Piirola added parts to the chapter on observational instruments, and Goran Sandell wrote the part about radio astronomy; chapters on magnitudes, radiation mechanisms and temperature were rewritten by the editors; Markku Poutanen wrote the chapter on the solar system; luhani Kyrolainen expanded the chapter on stellar spectra; Timo Rahunen rewrote most of the chapters on stellar structure and evolution; Ilkka Tuominen revised the chapter on the Sun; Kalevi Mattila wrote the chapter on interstellar matter; Tapio Markkanen wrote the chapters on star clusters and the Milky Way; Karl lohan Donner wrote the major part of the chapter on galaxies; Mauri Valtonen wrote parts of the galaxy chapter, and, in collaboration with Pekka Teerikorpi, the chapter on cosmology. Finally, the resulting, somewhat inhomogeneous, material was made consistent by the editors. The English text was written by the editors, who translated parts of the original Finnish text, and rewrote other parts, updating the text and correcting errors found in the original edition. The parts of text set in smaller print are less important material that may still be of interest to the reader. For the illustrations, we received help from Veikko Sink konen, Mirva Vuori and several observatories and individuals mentioned in the figure captions. In the practical work, we were assisted by Arja Kyrolainen and Merja Karsma. A part of the translation was read and corrected by Brian Skiff. We want to express our warmest thanks to all of them. Financial support was given by the Finnish Ministry of Education and Suomalaisen kirjallisuuden edistamisvarojen valtuuskunta (a foundation promoting Finnish literature), to whom we express our gratitude. Helsinki, June 1987 The Editors

8 Contents 1. Introduction The Role of Astronomy Astronomical Objects of Research The Scale of the Universe Spherical Astronomy Spherical Trigonometry The Earth The Celestial Sphere The Horizontal System The Equatorial System The Ecliptic System The Galactic Coordinates Perturbations of Coordinates Constellations Star Catalogues and Maps Positional Astronomy Time Reckoning Astronomical Time Systems Calendars Examples Exercises Observations and Instruments Observing Through the Atmosphere Optical Telescopes Detectors and Instruments Radio Telescopes Other Wavelength Regions Other Forms of Energy Examples Exercises Photometric Concepts and Magnitudes Intensity, Flux Density and Luminosity Apparent Magnitudes Magnitude Systems Absolute Magnitudes Extinction and Optical Thickness Examples Exercises

9 x Contents 5. Radiation Mechanisms Radiation of Atoms and Molecules The Hydrogen Atom Quantum Numbers, Selection Rules, Population Numbers Molecular Spectra Continuous Spectra Blackbody Radiation Other Radiation Mechanisms Radiative Transfer Examples Exercises Temperatures Examples Exercises Celestial Mechanics Equations of Motion Solution of the Equation of Motion Equation of the Orbit and Kepler's First Law Orbital Elements Kepler's Second and Third Law Orbit Determination Position in the Orbit Escape Velocity Virial Theorem The Jeans Limit Examples Exercises The Solar System An Overview Planetary Configurations Orbit of the Earth Orbit of the Moon Eclipses and Occultations Albedos Planetary Photometry, Polarimetry and Spectroscopy Thermal Radiation of the Planets The Structure of Planets Planetary Surfaces Atmospheres and Magnetospheres Mercury Venus The Earth and the Moon Mars Asteroids Jupiter Saturn Uranus, Neptune and Pluto

10 Contents XI 8.20 Minor Bodies of the Solar System Cosmogony Other Solar Systems Examples Exercises Stellar Spectra Measuring Spectra The Harvard Spectral Classification The Yerkes Spectral Classification Peculiar Spectra The Hertzsprung-Russell Diagram Model Atmospheres What Do the Observations Tell Us? Exercises Binary Stars and Stellar Masses Visual Binaries Astrometric Binary Stars Spectroscopic Binaries Photometric Binary Stars Examples Exercises Stellar Structure Internal Equilibrium Conditions Physical State of the Gas Stellar Energy Sources Stellar Models Examples Exercises Stellar Evolution Evolutionary Time Scales The Contraction of Stars Towards the Main Sequence The Main Sequence Phase The Giant Phase The Final Stages of Evolution The Evolution of Close Binary Stars Comparison with Observations The Origin of the Elements Examples Exercises The Sun Internal Structure The Atmosphere Solar Activity Examples Exercises

11 XII Contents 14. Variable Stars Classification Pulsating Variables Eruptive Variables Examples Exercises Compact Stars White Dwarfs Neutron Stars Black Holes Examples Exercises The Interstellar Medium Interstellar Dust Interstellar Gas Interstellar Molecules The Formation of Proto stars Planetary Nebulae Supernova Remnants The Hot Corona of the Milky Way Cosmic Rays and the Interstellar Magnetic Field Examples Exercises Star Clusters and Associations Associations Open Star Clusters Globular Star Clusters Examples Exercises The Milky Way Methods of Distance Measurement Stellar Statistics The Rotation of the Milky Way The Structure and Evolution of the Milky Way Examples Exercises Galaxies The Classification of Galaxies Luminosities and Masses Galactic Structures Dynamics of Galaxies Stellar Ages and Element Abundances in Galaxies Systems of Galaxies Active Galaxies and Quasars The Origin and Evolution of Galaxies Exercises

12 Contents XIII 20. Cosmology Cosmological Observations The Cosmological Principle Homogeneous and Isotropic Universes The Friedmann Models Cosmological Tests History of the Universe The Future of the Universe Examples Exercises Appendices A. Mathematics A.1 Geometry A.2 Taylor Series... " 465 A.3 Vector Calculus A.4 Conic Sections A.5 Multiple Integrals A.6 Numerical Solution of an Equation B. Quantum Mechanics... " 473 B.l Quantum Mechanical Model of Atoms. Quantum Numbers B.2 Selection Rules and Transition Probabilities B.3 Heisenberg's Uncertainty Principle... " 474 B.4 Exclusion Principle C. Theory of Relativity... " 475 C.l Basic Concepts C.2 Lorentz Transformation. Minkowski Space C.3 General Relativity... " 478 C.4 Tests of General Relativity... " 479 D. Radio Astronomy Fundamentals D.1 Antenna Definitions... " 480 D.2 Antenna Temperature and Flux Density E. Tables Answers to Exercises Further Reading Photograph Credits Name and Subject Index Colour Supplement.... " 523

13 The Virgo cluster of galaxies. Each galaxy conta ins hundreds of billions of stars (Photograph National Optical Astronomy Observatories)