Eclipsing Binary Stars Springer Science+Business Media, LLC Josef Kallrath Eugene F. Milone Eclipsing Binary Stars Modeling and Analysis Foreword by R.E. Wilson With 131 Illustrations , Springer Josef Kallrath Eugene F. Milone BASF-AG Department of Physics and Astronomy ZOIfZC-C13 University of Calgary D-67056 Ludwigshafen 2500 University Drive NW Gennany Calgary, Alberta T2N IN4 and Canada Department of Astronomy University of Florida Gainesville, FL 32611 USA Library of Congress Cataloging-in-Publication Data Kallrath, losef. Eclipsing binary stars: modeling and analysis / loser Kallrath, Eugene F. Milone. p. cm. Includes bibliographical references and index. I. Eclipsing binaries-Light curves. I. Milone, E.F., 1939- 11. Title. m. Series. QB82l.K36 1998 523.8'444-dc21 98-30562 Printed on acid-free paper. ISBN 978-1-4757-3130-9 ISBN 978-1-4757-3128-6 (eBook) DOI 10.1007/978-1-4757-3128-6 © 1999 Springer Science+Business Media New York Originally published by Springer-Verlag New York, Inc. in 1999. Softcover reprint ofthe hardcover 1st edition 1999 All rights reserved. This work may not be translated or copied in whole or in part without the written permission of the publisher Springer Science+Business Media, LLC except for brief excerpts in connection with reviews or scholarly analysis. Use in connection with any form of information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed is forbidden. The use of general descriptive names, trade names, trademarks, etc., in this publication, even if the former are not especially identified, is not to be laken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act, may accordingly be used freely by anyone. Production managed by Timothy Taylor; manufacturing supervised by Nancy Wu. Photocomposed copy prepared from the authors' u,'IEX files. 987654321 SPIN 10691992 Professori Dr. Hans Schmidt, magisto doctissimo ac clarissimo, patri et amico hoc opus votis optimis D.D.D. J. Kallrath To Harlan Smith and Adriaan Wesselink, teachers extraordinaire, and to my great fortune, my graduate advisors. E.F. Milone Foreword Have you ever stopped at a construction project on the way to your office and the day's astrophysics? Remember the other onlookers-folks just en joying the spectade, as we all do in following developments away from our areas of active work? We are excited and thrilled when the Hubble Space Telescope discovers an Einstein Cross, when the marvelous pulsars enter our lives, and when computer scientists put a little box on our desk that out-performs yesterday's giant machines. We are free to make use of such achievements and we respect the imagination and discipline needed to bring them about, just as onlookers respect the abilities and planning needed to create a building they may later use. After all, each of us contributes in our own areas as best we can. In addition to the serious onlookers there will be passers-by who take only a casual look at the site. They may use the building later, but have little or no interest in its construction, and give no thought to the resources needed to bring it to completion. Upon arriving at work, those persons write astronomy and astrophysics books at various levels, in which they must say something about dose binary stars. Usually a page or two will do, and the emphasis is on the MLR (mass, luminosity, radius) data obtained only from binaries. The role of binaries in stellar evolution also may be awarded a page or so, perhaps meshed with binaries being hornes of black-holes and neutron stars. We live in an era of ever more applied research, with national priorities set by the interests and judgments of select committees. Consequently, most authors tell us the answer to one central quest ion: What have binaries done for us lately? Well, of course, binaries are alive and well as sources of fundamental information on many fronts. But what of the fun, intrigue, and beauty of dose binaries? viii Foreword However I do not want to be hard on the generic text authors because I remember my initial reaction to binaries. A fellow graduate student (later a very accomplished researcher) was doing a binary star project and I could not imagine why he was so interested. He tried to explain it all, but it just was not working: subject = nonexciting. However I soon was into binaries anyway, just due to being surrounded by binary star work (yes, with ap palling conformity). Time went by and then something happened to turn the view around - it was Su Shu Huang's work on f Aurigae and also on ß Lyrae. Here was pure distilled cleverness and insight. Huang looked at problems that had been examined exhaustively by several of the most cele brated astrophysicists and saw things that had eluded everyone. Suddenly binaries were locales where mystery could transform into understanding if one looked in the right way. But where does one learn to do this sort of thing, in a course? Not at most schools. Can one learn from a book? WeIl, there are books on binary stars, but they mainly serve as repositories of formulas, derivations, and diagrams, and some follow the ideas of only one person or "school." A few books give recipes for procedures developed by their authors, usually without providing insight. There has long been a need for a book that takes a wide view of binary star models and their interface with observations, and that is the goal set by Josef Kallrath and Eugene F. Milone, who together have broad experience in binary star models and observations. Their creation has conscientious coverage throughout most of the "models versus observations" field. It can guide interested persons into the overall field and be a helpful companion as they explore new ex amples, such as in the initial approach (what is going on?), a settling-in stage (is it a standard situation or are their complications?), getting up to speed (developing intuition and extracting maximum information), and finally evaluation of results. Examine the Contents to see a variety of topics not found in the few preceding books in this general area. Here we find extensive treatment of history, terminology, observational methods, accuracy, binary models from the ground up, system morphology, a sense of where things are going, per spectives for long-range development, guides to exploration ofthe literature, and even philosophy. Although not all important categories of binaries are covered, nor are all individual binaries of special interest, the coverage in this first edition is remarkable. Protest marches for inclusion of symbiotics, ultra-compact X-ray binaries, etc., in future editions may weIl be successful. For now the emphasis is on more general considerations. We see a balance between hands-on and automated analysis. Extreme hands-on advocates typically get things roughly right and can recognize novel features but fail to extract all available information. Extreme advocates of the automated school can reach optimal solutions for standard cases but miss anything new (there is more to astrophysics than parameter adjustment). We need to navigate between these extremes. The names of same luminaries of the binary star field may seem to be Foreword ix under-represented, for example, those in structure and evolution. Should we not be reading more about Eggleton, Kippenhahn, Lucy, Ostriker, Paczyn ski, Plavec, Taam, van den Heuvel, Webbink, etc.? But remember that it is a book about direct representation of observations through models and must be kept to a reasonable size, and there are excellent books on structure and evolution. Although the scope is limited to models, observations, and related math ematics, there is something here for everyone. Thus we leam that the Kolmogorov-Smimoff test is not, after all, a way to distinguish vodkas. And there are binaries for everyone. Game players will like the one that stays in eclipse 90% of the time and comes out for only 10% (PK Boa). Gadget afficianados prefer the remote paging device, b Per. We have a thing to play in TV Cet and a place to stay in HO Tel. And then there is the only star with a quest ion mark in its name (Y Sex?). So peruse thc book, leam from it, and enjoy close binaries. If you happen to find some MLR data along the way, so much the better. Gainesville, Florida February 17 1998 R.E. Wilson Preface Di, coepits ... adspirate meis (Gods, aid my undertaking) -Ovid (43 B.C.-A.D. 17), Metamorphoses 1,2-4 This book arose from the realization that light curve modeling has not had a full expository treatment in 40 years. The last major exposition was that of Russell and Merrill (1952), and that treatment dealt exclusively with the Russell-Merrill spherical star model, and with the process of light curve rectification. The present work may be the first comprehensive exposition of the merits of the major modern light curve analysis methods, notwith standing the pioneer efforts of many investigators beginning with Kopal (1950), who again described mainly his own efforts. The need for a source book and didactic presentation on the subject was recognized in the course of planning a conference on light curve modeling which was held in Buenos Aires and Cordoba in July-August, 1991. The proceedings of the Argentina meetings (Milone, 1993) review the current state of light curve modeling methods and focus on special topics but do not give a general review. The only previous meeting devoted exclusively to the topic of comparative light curve modeling methods was lAU Colloquium No. 16 in Philadelphia in September 1971. Although there is an extensive literat ure on eclipsing binary research, the paucity of instructional materials in the area of light curve analysis is striking. The graduate student, the researcher, or the advanced amateur astronomer must struggle through journal articles or conference proceed ings and must read between the lines to glean the details of the modeling process. Most of the didactic books on light curve modeling date to the