Astronomers Observing Guides

Astronomers Observing Guides

Other titles in this series The Moon and How to Observe It Peter Grego Related titles Field Guide to the Deep Sky Objects Mike Inglis Deep Sky Observing Steven R. Coe The Deep-Sky Observer s Year Grant Privett and Paul Parsons The Practical Astronomer s Deep-Sky Companion Jess K. Gilmour Observing the Caldwell Objects David Ratledge Choosing and Using a Schmitt-Cassegrain Telescope Rod Mollise

James Mullaney Double and Multiple Stars and How to Observe Them With 45 Figures

Series Editor: Dr. Mike Inglis, FRAS Cover illustration: A red dwarf, shown in the background, is at the mercy of its highly magnetic white dwarf companion in this depiction of a so-called intermediate polar binary system. Gas lost from the red star is channelled toward the white dwarf s poles along magnetic field lines, where it emits the X-rays that make these systems so powerful. All illustrations noted Courtesy of Sky & Telescope in the captions are copyright Sky & Telescope and Sky Publishing Corporation, and are used with their kind permission. British Library Cataloguing in Publication Data Mullaney, James Double and multiple stars and how to observe them. (Astronomers observing guides) 1. Double stars-observers manuals 2. Double stars- Observations 3. Multiple stars-observers manuals 4. Multiple stars-observations I.Title 523.8 41 ISBN 1852337516 Library of Congress Cataloging-in-Publication Data Mullaney, James. Double and multiple stars and how to observe them / James Mullaney. p. cm (Astronomers observing guides) Includes bibliographical references and index. ISBN 1-85233-751-6 (acid-free paper) 1. Multiple stars Observations. I. Title. II. Series. QB821.M83 2005 523.8 41 dc22 2004065359 Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copyright Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. Astronomers Observing Guides Series ISSN 1611-7360 ISBN 1-85233-751-6 Springer Science+Business Media springeronline.com Springer-Verlag London Limited 2005 Printed in the Singapore The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Observing the Sun, along with a few other aspects of astronomy, can be dangerous. Neither the publisher nor the author accept any legal responsibility or liability for personal loss or injury caused, or alleged to have been caused, by any information or recommendation contained in this book. Typeset by EXPO Holdings, Malaysia 58/3830-543210 Printed on acid-free paper SPIN 10930076

Preface Preface You are holding in your hands, dear Reader, your passport to an exciting cosmic adventure exploring the universe of double and multiple stars! These are the sky s tinted jewels and waltzing couples, and they are waiting patiently in the darkness of night to dazzle and delight you. This is actually two books in one. The first part surveys the current state of knowledge about double stars how they are born, evolve and interact, their significance in the cosmic scheme of things, and the valuable insights they provide into such fundamental matters as stellar masses and the ultimate fate of stars. The more we know about these fascinating objects, the more enjoyment we will ultimately derive from actually viewing them firsthand with binoculars and telescopes from our gardens or backyards or fields. As Charles Edward Barns stated in his long out-of-print classic 1001 Celestial Wonders, Let me learn all that is known of them, Love them for the joy of loving. For, as a traveler in far countries Brings back only what he takes, So shall the scope of my foreknowledge Measure the depth of their profit and charm to me. The second part of this book is an observing guide that tells the reader how and what to look for, examines the use of various types of telescopes and accessories (including such modern ones as video and CCD imaging devices), and offers a selection of fascinating projects suitable for novice stargazers as well as advanced amateurs. These projects range from those intended for the reader s own pleasure and edification to those that actually have the potential of contributing to the science of double star astronomy itself. The highlight of the second section (and, indeed, perhaps of the entire book!) are two carefully compiled observing rosters one showcasing 100 of the sky s finest double and multiple stars for viewing with telescopes from 2 to 14 inches in aperture, and the other a more extensive tabulation of 400 additional pairs for further exploration and study. Together, these two lists offer 500 selected stellar wonders for your enjoyment. The material in this book is based on decades of studying double stars by the author as a professional observer and more than half a century as a passionate stargazer surveying the heavens for its visual treasures especially striking double and multiple stars! These observations were made using everything from 7 50 and 10 50 binoculars to refracting telescopes from 2 to 30 inches (!) in v

Preface aperture, reflecting telescopes from 3 to 36 inches, and catadioptric telescopes from 3.5 to 22 inches in size. It is my sincere wish that you, the reader, will find the same joy and satisfaction in becoming personally acquainted with these fascinating objects as I continue to do even after all those years and all those telescopes! In closing, we again quote from Barns: Lo, the Star-lords are assembling, And the banquet-board is set; We approach with fear and trembling. But we leave them with regret. James Mullaney Rehoboth Beach, Delaware vi

Acknowledgments There are many people in the astronomical and publishing community who have helped to make this book a reality. In particular, my many friends at Sky & Telescope and its parent company Sky Publishing Corporation have been especially helpful in supplying information and illustrations that have appeared in the magazine. Special thanks in this regard is due to Sally MacGillivray, Rights & Permissions Manager at Sky. Dr. Nicholas Wagman, deceased director of the University of Pittsburgh s Allegheny Observatory, was both kind friend and mentor while I served on the staff there. He gave me unlimited use of its superb 13-inch Fitz-Clark refractor (and occasionally its 30-inch Brashear refractor as well!) for my early visual sky surveys and work on double stars. The late Dr. Charles Worley long one of the world s leading double star observers with the 26-inch Clark refractor at the United States Naval Observatory and the astronomer primarily responsible for maintaining the monumentalwashington Double Star Catalog (the WDS) was also a valued source of information and inspiration to me. Since his passing, Dr. Brian Mason and his staff have taken over the task of keeping the WDS updated, and special thanks must be given them on behalf of the entire astronomical community for this vital service. Dr. John Watson, FRAS, and Dr. Michael Inglis, FRAS my editors at Springer-Verlag London have patiently guided me throughout this project and have been a sincere pleasure to work with. So too has been Louise Farkas, Senior Production Editor, at Springer New York. Finally, I wish to acknowledge my dear wife, Sharon McDonald Mullaney, who has been a constant source of help and encouragement during the long process of writing this book. Acknowledgments vii

Contents Part I All About Double and Multiple Stars 1 Introduction..................................... 3 Series and Book Objectives............................. 3 Double and Multiple Stars Defined......................... 3 The Joys of Seeing Double............................. 3 Demise of a Once-Vital Field of Astronomy.................... 6 2 Types of Double Stars................................ 9 Optical versus Physical Doubles.......................... 9 Common Proper Motion (CPM) Pairs...................... 11 Visual Binaries................................... 12 Interferometric Binaries.............................. 14 Astrometric Binaries................................ 14 Spectroscopic Binaries............................... 16 Eclipsing Binaries................................. 17 Multiple Star Systems............................... 19 Cataclysmic Binaries................................ 21 Contents 3 Astrophysics of Double Stars........................... 23 Frequency and Distribution of Double Stars................... 23 The Genesis of Binary Stars............................ 24 Determination of Stellar Masses......................... 25 Distances of Double Stars............................. 25 Double Stars and The Mass Luminosity Relation................ 27 Mass Exchange in Contact Binaries........................ 28 Stellar Mergers................................... 29 A Two-Minute Binary?............................... 30 Planetary Systems................................. 31 Part II Observing Double and Multiple Stars 4 Observing Techniques............................... 35 Training the Eye.................................. 35 ix

Sky Conditions................................... 37 Star Testing and Collimation........................... 39 Record Keeping................................... 41 Personal Matters.................................. 42 5 Tools of the Trade................................. 43 Refracting Telescopes............................... 43 Reflecting Telescopes................................ 44 Catadioptric Telescopes.............................. 46 Eyepieces...................................... 47 Star Diagonals................................... 48 Barlow Lenses................................... 49 Micrometers..................................... 50 Photographic, Video and CCD Imaging Systems................ 53 Star Atlases and Catalogues............................ 55 Miscellaneous Items................................ 56 Contents 6 Observing Projects................................. 60 Sightseeing Tour.................................. 61 Color Studies.................................... 61 Resolution Studies................................. 64 Micrometer Measurements............................ 67 Orbit Calculation and Plotting.......................... 71 New Pair Survey.................................. 73 Founding a Double Star Observers Society................... 74 7 Double and Multiple Star Observing Lists.................... 75 One Hundred Showpiece Double and Multiple Stars.............. 76 8 Conclusion..................................... 85 Reporting and Sharing Observations....................... 85 Pleasure versus Serious Observing........................ 87 Aesthetic and Philosophical Considerations................... 88 Appendices 1 Constellation Names and Abbreviations..................... 91 2 Double Star Designations............................. 94 3 Double and Multiple Star Working List.................... 101 4 Telescope Limiting Magnitude and Resolution................ 121 5 The Measurement of Visual Double Stars................... 123 About the Author.................................. 127 Index......................................... 129 x

Part I All About Double and Multiple Stars