ESO ASTROPHYSICS SYMPOSIA European Southern Observatory ——————————————————— Series Editor: Bruno Leibundgut S. Hubrig M. Petr-Gotzens A. Tokovinin (Eds.) Multiple Stars Across the H-R Diagram Proceedings of the ESO Workshop held in Garching, Germany, 12-15 July 2005 Volume Editors Swetlana Hubrig Andrei Tokovinin European Southern Observatory Inter-American Observatory 3107 Alonso de Cordova Cerro Tololo (CTIO ) Santiago, Vitacura La Serena Chile Chile Monika Petr-Gotzens European Southern Observatory Karl-Schwar schild-Str. 2 85748 Garching Germany Series Editor Bruno Leibundgut European Southern Observatory Karl-Schwarzschild-Str. 2 85748 Garching Germany Library of Congress Control Number: 2007936287 ISBN 978-3-540-74744-4 Springer Berlin Heidelberg New York This work is subject to copyright. 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Cover design: WMXDesign, Heidelberg Typesetting: by the authors Production: Integra Software Services Pvt. Ltd., Puducherry, India Printed on acid-free paper 55/3180/Integra 543210 Preface The ESO workshop “Multiple Stars across the H-R Diagram” was held in Garching on 12–15, July 2005. The topics included observations of multiple stars from ground and space, dynamical and stellar evolution in multiple systems, effects of the environment on multiplicity, formation and early evo- lution of multiple stars, and special components of multiple stars (chemically peculiar stars, blue stragglers, brown dwarfs, etc.). Stars show a marked tendency to be in systems of different multiplicity, ranging from simple binaries and triples to globular clusters with N≈107. Modern observations give a frequency of binary and multiple stars in the Galactic field of up to 70%, and between 5% and 20% of these systems are at least triple. There is evidence that the degree of multiplicity increases with primary mass. Many known multiple systems are too wide to have sig- nificant physical interaction between their components. However, tidal and N-body dynamical interactions are important even in relatively wide sys- tems and probably lead to the shrinkage of inner orbits. This sets the stage for spectacular evolutionary processes such as Roche-lobe overflow, merg- ers, supernovae, formation of special components, etc. Only recently did we realize that some of these processes require at least three stars. The formation of multiple systems remains a difficult and challenging part of astrophysics, although it has been addressed at the Workshop only briefly. Instead, we concentrated on the subsequent stages, more precisely, on how the components, evolution may affect multiple systems and whether there is a difference in comparison to binary stars. The growing information on triple and higher-multiplicity systems with a variety of characteristics has been used to examine critically the assumptions underlying stellar evolutionary models. The purpose of this meeting was to bring together teams interested in studies of X-ray, UV, visual, near-IR and far-IR properties of stars of all types which are members of multiple systems, and covering stars of high, intermediate and low mass, thus combining specialists with complementary expertise. The Workshop was well timed, since major developments hap- pened in this field of research during recent years due to the availability of large-aperture telescopes equipped with highly sophisticated instruments for multi-wavelength observations, modern interferometers (VLTI, Keck interfer- ometer, CHARA array, etc.) and new satellites such as Chandra, Fuse and VI Preface the Spitzer Space Telescope. The combination of results from satellites and ground-based facilities resulted in vivid interaction between the experts of all stellar type. The current state of observational and theoretical knowledge has been reviewed, and priorities for future studies have been discussed, so as to provide the necessary input for further progress in the understanding of the genesis of multiple stars, their structure and their role for the study of stellar evolution. Altogether, 47 people from 16 countries attended this meeting, showing that it was fulfilling a real need. Indeed, the reader will realize that significant progress has been made in the last years, especially in the studies of dynamical evolution in multiple stars, the effects of the environment on multiple system parameters, stellar evolution within multiple stars, multiplicity of massive stars, pre-Main-Sequence multiple systems of intermediate mass, multiplicity of low-mass stars from embedded protostars to open clusters, and brown dwarfs and planets in multiples. We look forward to the future progress which will be presented in a few special sessions at the IAU Symposium 240 “Binary Stars as Critical Tools and Tests in Contemporary Astrophysics” during the XXVI-th IAU General Assembly in Prague this year. We are grateful to all participants for stimulating presentations and dis- cussions. We thank the local organizing committee chaired by Monika Petr- Gotzens and the European Southern Observatory which fully sponsored this conference. Santiago and La Serena, Chile Swetlana Hubrig May 2006 Andrei Tokovinin Contents Evolutionary Processes in Multiple Systems P.P. Eggleton and L. Kisseleva-Eggleton ........................... 1 Dynamics and Stability of Triple Stars Seppo Mikkola .................................................. 11 Multiple Stars: Physics vs. Dynamics R. Zhuchkov, V. Orlov and A. Rubinov ............................ 21 Gliese 225.2: An Old (Stable?) Quadruplet V. Orlov, A. Tokovinin, O. Kiyaeva, M. Sterzik, A. Rubinov and R. Zhuchkov .................................................... 31 Multiple Stars: Designation, Catalogues, Statistics A. Tokovinin ................................................... 37 Radial-velocity Studies of Certain Multiple Systems R.F. Griffin .................................................... 43 Spectral Disentangling Applied to Triple Systems: RV Crt H. Hensberge, L.P.R. Vaz, K.B.V. Torres and T. Armond............ 47 Evidence for Rapid Variability in the Multiple System 68 u Her K. Uytterhoeven, P. Koubsk´y, P. Harmanec, J.H. Telting, S. Yang, M.T. Richards and I. Ilyin ....................................... 53 DG Leo: A Triple System with a Surprising Variety of Physical Phenomena P. Lampens, Y. Fr´emat, H. Hensberge, V. Tamazian, J.A. Docobo and Y. Balega ...................................................... 59 A Spectroscopic Study of HD 208905 Pavel Koubsk´y, Simone Daflon, Petr Hadrava, Katia Cunha,, Jiˇr´ı Kub´at, Dana Korˇc´akov´a, Petr Skoda,ˇ Miroslav Slechta,ˇ Viktor Votruba, Verne V. Smith and Dimitri Bizyaev ................ 67 The Suspected Binarity of the Nearby Flare Star Gl 424 V.S. Tamazian, J.A. Docobo and Y.Y. Balega ...................... 71 VIII Contents The Ecology of Dense Star Clusters with Binaries Simon F. Portegies Zwart ........................................ 75 The Formation of Multiple Stars Eduardo J. Delgado-Donate and Cathie J. Clarke ................... 87 Population of Dynamically Formed Triples in Dense Stellar Systems Natalia Ivanova ................................................. 101 Interferometric Studies of Multiple Stars Christian A. Hummel ............................................ 107 Interferometric Orbits of New Hipparcos Binaries I.I. Balega, Y.Y. Balega, K.-H. Hofmann, E.V. Malogolovets, D. Schertl, Z.U. Shkhagosheva and G. Weigelt ...................... 113 New Facts about δ Velorum: Fewer but Larger Components A. Kellerer, M.G. Petr-Gotzens, P. Kervella and V. Coud´e du Foresto . 119 Speckle Interferometry of Two Low-mass Triple Systems in the Solar Neighbourhood E.V. Malogolovets, Y.Y. Balega, K.-H. Hofmann, D.A. Rastegaev and G. Weigelt ..................................................... 125 Tertiary Companions to Close Spectroscopic Binaries A. Tokovinin, S. Thomas, M. Sterzik and S. Udry .................. 129 Spectroscopic Subcomponents in Visual Double Stars: The Most Probable Values of their Physical and Orbital Parameters. Application to the System WDS 14404+2159 Jos´e A. Docobo and Manuel Andrade .............................. 137 Multiple Stars in the Field Brian D. Mason and William I. Hartkopf .......................... 141 Multiplicity of Chemically Peculiar Stars Swetlana Hubrig, Nancy Ageorges and Markus Sch¨oller .............. 155 Multiplicity of Contact Binary Stars T. Pribulla and S.M. Rucinski .................................... 163 Extrasolar Planets in Double and Multiple Stellar Systems A. Eggenberger, S. Udry, M. Mayor, G. Chauvin, B. Markus, J.-L. Beuzit, A.-M. Lagrange, T. Mazeh, S. Zucker and D. S´egransan . 169 Homogeneous Comparison of Directly Detected Planet