DYNAMICS OF STAR CLUSTERS - Springer978-94-009-5335-2/1.pdf · I.A.D. Symposium to discuss the...
Transcript of DYNAMICS OF STAR CLUSTERS - Springer978-94-009-5335-2/1.pdf · I.A.D. Symposium to discuss the...
DYNAMICS OF STAR CLUSTERS
INTERNATIONAL ASTRONOMICAL UNION
UNION ASTRONOMIQUE INTERNA TIONALE
DYNAMICS OF STAR CLUSTERS
PROCEEDINGS OF THE 113th SYMPOSIUM OF THE INTERNA TIONAL ASTRONOMICAL UNION, HELD IN PRINCETON, NEW JERSEY, U.S.A,
29 MAY - 1 JUNE, 1984
EDITED BY
JEREMY GOODMAN California Institute of Technology,
Pasadena, California, U.S.A.
and
PIET HUT The Institute for Advanced Study,
Princeton, New Jersey, U.S.A.
D. REIDEL PUBLISHING COMPANY
A MEMBER OF THE KLUWER ACADEMIC PUBLISHERS GROUP
DORDRECHT/BOSTON/LANCASTER
Library of Congress Cataloging in Publication Data
International Astronomical Union. Symposium (1 13th: 1984: Princeton, N.J.) Dynamics of star clusters.
Includes index. 1. Stars-Clusters-Congresses. 2. Stars-Globular clusters-Congresses.
3. Stars-Open clusters-Congresses. I. Goodman, Jeremy, 1956-II. Hut, Piet, 1952- III. Title. QB853.I58 1984 523.8'5 85-1870
ISBN-13: 978-90-277-1965-2 e-ISBN-13: 978-94-009-5335-2 DOl: 10.1007/978-94-009-5335-2
Published on behalf of the International Astronomical Union
by D. Reidel Publishing Company, P. 0. Box 17, 3300 AA Dordrecht, Holland
All Rights Reserved © 1985 by the International Astronomical Union
Softcover reprint of the hardcover 1 st edition 1985
Sold and distributed in the U.S.A. and Canada by Kluwer Academic Publishers,
190 Old Derby Street, Hingham, MA 02043, U.S.A.
In all other countries, sold and distributed by Kluwer Academic Publishers Group,
p. 0. Box 322, 3300 AH Dordrecht, Holland
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 information storage and retrieval system, without written permission from
the publisher
TABLE OF CONTENTS
Preface Conference Photograph (Frontispiece) List of Participants
MAY 29 OBSERVATIONS OF GLOBULAR CLUSTERS
Ivan R. King OBSERVED SURFACE DENSITIES IN GLOBULAR CLUSTERS
Robert Lupton, James E. Gunn & Roger F. Griffin RADIAL VELOCITIES AND PROPER MOTIONS OF GLOBULAR CLUSTER STARS
Ie C. Freeman CHEMICAL GRADIENTS IN GLOBULAR CLUSTERS
Jonathan E. Grindlay X-RAYING THE DYNAMICS OF GLOBULAR CLUSTERS
M.. Auriere, J. P. Cordoni, O. Le Fevre, A. Terzan A HIGH SPATIAL RESOLUTION INVESTIGATION OF THE CORE OF SOME DYNfu~ICALLY EVOLVED GLOBULAR CLUSTERS
Kyle Cudworth, D.N.C. Lin&K.-S. Oh DYNAMICAL MODELING OF M13 PROPER MOTIONS
G.S. Da Costa & K.C. Freeman THE DYNAMICS OF 47 TUCANAE
S. Djorgovs'ki & H. Penner A SEARCH FOR POST-COLLAPSE CORES
P.J. Godwin CORE AND TIDAL RADI I OF THE CARINA mJAl-a·' SPHEROIDAL GALAXY FROM UK SCHMIDT TELESCOPE PLATES
William E. Harris & James E. Hesser A DEEP LUMINOSITY FUNCTION FOR 47 TUCANAE
E. Kontizas & M. Kontizas OBSERVED DYNAMICAL PARAMETERS OF STAR CLUSTERS IN THE SMC
xi xvi ixx
1
19
33
43
63
65
69
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81
85
vi TABLE OF CONTENTS
P.M. Lugger, H. Cohn and J.E. Grindlay WHERE'S THE CUSP? (OR CCD PHOTOMETRY OF GLOBULAR CLUSTER CORES) 89
G. Meylan & M. Mayor ROTATIONAL FIELD AND VELOCITY DISPERSION IN GLOBULAR CLUSTERS: 93 w CEN AND 47 TUC
Charles J. Peterson BV CONCENTRIC APERTURE PHOTOMETRY OF GLOBULAR CLUSTERS 97
C.P. Pryor, David W. Latham & Martha L. Hazen-Liller AN EXTENSION OF THE SEARCH FOR SPECTROSCOPIC BINARIES IN M3 99
M.M. Shara, A.F.J. Moffat & D.A. Hanes A SEARCH FOR CATACLYSMIC BINARIES IN THE GLOBULAR CLUSTER M3 103
Graeme H. Smith POSSIBLE CHARACTERISTICS OF SUPERNOVA INDUCED ENRICHMENT OF 105 GLOBULAR CLUSTERS
DYNAMICAL EVOLUTION OF GLOBULAR CLUSTERS
Lyman Spitzer, Jr. PRE COLLAPSE EVOLUTION OF GLOBULAR CLUSTERS 109
Douglas C. Heggie DYNAMICAL EVOLUTION OF GLOBULAR CLUSTERS AFTER CORE COLLAPSE 139
MAY 30 MODEL SYSTEM IN THE POINT-MASS APPROXIMATION
Haldan Cohn DIRECT FOKKER-PLANCK CALCULATIONS
Jeremy Goodman CLOSE ENCOUNTERS
Shogo Inagaki DYNAMICAL EVOLUTION OF MULTI-COMPONENT CLUSTERS
Daiichiro Sugimoto GASEOUS MODELS
Erich Bettwieser GRAVOTHERMAL OSCILLATIONS
Piet Hut BINARY FORMATION AND INTERACTIONS WITH FIELD STARS
Sverre J. Aarseth DIRECT N-BODY CALCULATIONS
161
179
189
207
219
231
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TABLE OF CONTENTS
Alan P. Lightman & Stephen L. W. McMillan A UNIFIED N-BODY AND STATISTICAL TREATMENT OF STELLAR DYNAMICS
J.G. Jernigan DIRECT N-BODY SIMULATIONS WITH A RECURSIVE CENTER OF MASS REDUCTION AND REGULARIZATION
S. Michael Fall & Carlos S. Frenk ROTATION AND FLATTENING OF GLOBULAR CLUSTERS
Joshua Barnes DYNAMICAL INSTABILITIES IN SPHERICAL STELLAR SYSTEMS
E. Bettwieser, K.J. Fricke, R. Spurzem WHY ARE STELLAR SYSTEMS ANISOTROPIC?
Stefano Casertano A STATISTICAL TREATMENT OF LOW-N SYSTEMS
Jacques Colin MINIMUM OF THE ECCENTRICITY OF THE GALACTIC GLOBULAR CLUSTER ORBITS
Eldad Dagan FUNCTIONAL INTEGRALS IN STELLAR DYNAMICS
Emmanuel Davoust MULTI-COMPONENT MODELS FOR THE STRUCTURE AND EVOLUTION OF SPHERICAL STELLAR SYSTEMS
G.Giannone & D. Molteni THE ROLE OF HARD BINARIES IN CLUSTER EVOLUTION
Henry E. Kandrup COLLISIONAL STELLAR DYNAMICS IN GENERAL RELATIVITY: AN OVERVIEW
Robert Lupton 3-INTEGRAL MODELS FOR GLOBULAR CLUSTERS
Stephen L.W. McMillan THE EARLY STAGES OF POST-COLLAPSE CLUSTER EVOLUTION
Seppo Mikkola NUMERICAL SIMULATIONS OF ENCOUNTERS OF HARD BINARIES
G. Severne & M. Luwel COLLISIONAL RELAXATION: A NEW APPROACH
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285
297
301
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309
313
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321
323
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335
339
viii TABLE OF CONTENTS
.MAY 31 EXTERNAL FIELDS AND FINITE-STAR-SIZE EFFECTS
P. Seitzer TIDAL EFFECTS o.N GLo.BULAR CLUSTERS 343
Jeremiah P. o.striker PHYSICAL INTERACTIo.NS BETWEEN STARS 347
J.S. Stod6lkiewicz Mo.NTE-CARLo. CALCULATIo.NS 361
Stuart L. Shapiro Mo.NTE CARLO. SIMULATIo.NS o.F THE 2+1 DIMENSIo.NAL Fo.KKER-PLANCK 373 EQUATIo.N: SPHERICAL STAR CLUSTERS Co.NTAINING MASSIVE, CENTRAL BLACK Ho.LES
Martin J. Duncan CAN A Mo.DERATELY MASSIVE BLACK Ho.LE REVERSE Co.RE Co.LLAPSE? 415
M. Giersz TWO. Bo.DY CAPTURE IN LARGE N Bo.DY SYSTEMS 419
Richard B. Larson BLACK-Ho.LE REMNANTS IN GLo.BULAR CLUSTERS 421
T.S. van Albada & T.R. Bontekoe TIDAL STRIPPING AND DISRUPTIo.N o.F GLo.BULAR CLUSTERS 423
o.PEN CLUSTERS
Robert D. Mathieu THE STRUCTURE AND INTERNAL KINEMATICS o.F o.PEN CLUSTERS
Roland Wielen DYNAMICS o.F o.PEN STAR CLUSTERS
Michael Margulis, Charles J. Lada and David Dearborn THE DYNAMICAL EVo.LUTIo.N o.F yo.UNG o.PEN CLUSTERS
A.F.J. Moffat, W. Seggewiss and M.M. Shara THE DENSE STELLAR Co.RES o.F GIANT HII REGIo.NS
Elena Terlevich N-Bo.DY SIMULATIo.NS o.F REALISTIC o.PEN CLUSTERS
Floor van Leeuwen A PRo.PER Mo.TIo.N STUDY o.F THE PLEIADES CLUSTER
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449
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TABLE OF CONTENTS
JUNE 1 THE DYNAMICS OF STAR CLUSTERS: FUTURE PROSPECTS
John N. Baheall SPACE TELESCOPE OBSERVATIONS OF GLOBULAR CLUSTERS
Lyman Spitzer, Jr., Chairman of the PANEL DISCUSSION: WHAT NEXT? PRIORITIES IN THEORY AND OBSERVATIONS
Jeremiah P. Ostriker SOME SUMMARY REMARKS
Appendix I: V. A. Arnbartsumian
APPENDICES
ON THE DYNAMICS OF OPEN CLUSTERS
Appendix II: V. A. Antonov MOST PROBABLE PHASE DISTRIBUTION IN SPHERICAL STAR SYSTEMS AND CONDITIONS FOR ITS EXISTENCE
Appendix III: R. F. Webbink STRUCTURE PARAMETERS OF GALACTIC GLOBULAR CLUSTERS
Appendix IV: Floor van Leeuwen PROPER MOTION STUDIES OF STARS IN AND AROUND OPEN CLUSTERS
Index of Names
Index of Subjects
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481
499
511
521
525
541
579
607
615
PREFACE
The emphasis in these proceedings of lAD Symposium No. 113, Dynafrri-,'!s of Star Clusters. and·.~.Le. mab rPIHlon for orZ'lnizinp: thE" symposium in the spring of 1984, was the rapid increase during the preceeding year in our understanding of core collapse. The last I.A.D. Symposium to discuss the dynamics of star clusters at length was No.69, Dynamics of Stellar Systems~ held in Besan~on in 1974. For a few years afterwards, globular clusters receiveu much attention due to the discovery of X-ray bursters and the mounting evidence that X-ray sources in globular clusters were formed in completely different ways than those within our galaxy. Globular clusters, which until this time had a reputation for sedate old age, turned out to lead violent private lives at high energies.
However, in the early 80's globular clusters seemed to lose some of the glamor of the 70's. The grand speculations of heavy black holes lurking in their centers had to make way for a variety of observational evidence which indicated that the X-ray sources are low-mass close binaries instead. But, though dynamical fashion turned to heavy galactic halos and so on, some of the unsolved theoretical problems regarding the evolution of star clusters kept their fascination for a number of relatively isolated workers. After several years of inconspicuous labor, a number of preprints suddenly appeared in the spring of 1983 that studied the evolution of globular clusters after core collapse. This problem had been recognized clearly in the heyday of X-ray enthusiasm, but with the notable exception of early work by Henon, all previous attempts to model post-collapse evolution posited the existence of a massive central black hole.
With the appearance of detailed models of the post-collapse regime, a renaissance in globular cluster evolutionary calculations occurred, comparable to the rapid progress in stellar evolution in the late 50's. It was this development which led us to propose this symposium. The international scientific organizing committee decided to organize the symposium in a slightly unusual fashion. Recognizing the many developments which had been taking place during the ten years since the previous lAD symposium in Besancon, the committee expressed their intention that the new symposium playa double role: to review those past developments; and to provide a forum for discussion of future directions of research, both theoretical and observational. The feeling of the organizers was that these goals could best be reached by scheduling only a limited number of invited speakers, together with a larger number of participants in poster sessions. In this way two objectives could be realized: the many new lines of research could be reviewed in a less hectic and more coherent way than would be possible if time were
xi
PREFACE
divided equally among all participants, and more time would be available between the talks for informal discussion. We will leave it to the participants and to the readers of these proceedings to judge the success of this plan.
We regret that Dr. L. M. Ozernoy was not able to attend the symposium and deliver his invited lecture, due to circumstances beyond his control. Although he informed us that he intended to submit the invited paper for the proceedings, we unfortunately had not yet received his contribution by the time these proceedings went to press.
We editors do appreciate the many positive reactions we received at the end of the symposium; the enthusiasm of the participants was all the more gratifying because of the nearly incessant rain that they suffered and that obscured a near-total eclipse. (The group photograph included here gives an utterly false impression of the usual weather, as any participant will admit.)
Those of you who actually read prefaces, and especially those who work on open clusters, may have noticed a bias in favor of globular clusters. The main reason for this is that much recent progress has been made in understanding the latter objects, whereas the dynamics of open clusters have been less well explored, both theoretically and observationally. In many ways the dynamics of open clusters are more difficult to study than those of globular clusters: theoretically, because the combination of the lower number of stars and the younger age of open clusters make a statistical description much more difficult and its validity more questionable; and observationally, because the velocity dispersion in'an open cluster is typically an order of magnitude lower than that in a globular cluster. These difficulties notwithstanding, significant progress has been made recently and is reported in these proceedings, and it is possible that in another ten years the study of open clusters may dominate a future star cluster symposium, in part because this study promises to increase our understanding of star formation in the galactic disk.
We express our hope that in the coming years the proceedings ,of this symposium will prove to be as valuable as those of its predecessor, I.A.D. Symposium 69, as a reference work for research on the dynamics of star clusters. To this end we urged all invited speakers to make a broad survey of their topics. In addition, on the final day of the symposium a discussion was held among a panel of six wise men to assess the scientific progress revealed by the conference and to identify the most promising directions for future research, a summary of which has been included here.
Four appendices have been added. The first contains an English translation of a classic paper by Arnbartsumian, in which he showed for the first time that the evolution of an isolated self-gravitating star cluster under the influence of two-body relaxation does not cease with the establishment of a maxwellian velocity distribution. The second appendix is a translation of that seminal paper by V.A. Antonov which led eventually to our present understanding of the gravothermal instability. We would have liked to include a translation of Michel Henon's (1961) Ph.D. thesis, which has been much neglected but predicted many of
PREFACE xili
the essential phenomena of cluster evolution after core collapse; we felt, however, that the paper was too long to include in this already lengthy volume. To honor H~non's fundamental contributions, we have instead reproduced one of the illustrations which appeared in his thesis, side to side with a new calculation (reported in these proceedings by Stodolkiewicz) confirming many of the results obtained by Henon nearly a quarter century ago. We hope that his thesis will soon appear in translation elsewhere and thereby become accessible to a larger fraction of those working presently on the dynamics of star clusters.
The third appendix contains a list of observed parameters of globular clusters with the original references, compiled by Webbink, and a similar list for open clusters, by van Leeuwen, forms the fourth appendix. These appendices should increase the long-term value of this book sufficiently, even with the inevitable increase of the volume and thereby the price of the present proceedings. A detailed index of names and subjects follows. This index covers all papers and discussions included in these proceedings with the exception of the appendices which are already written in the form of compilations.
We must apologize to the reader for our failure to correct many small errors of grammar and spelling (sometimes even in the spelling of names) in the camera-ready manuscripts; we felt that since none of these errors is likely to cause confusion, our limited resources and the importance of publishing the proceedings quickly required that we let them pass. For errors in the organization of the book and in the indices we are, of course, wholly responsible.
We acknowledge the assistance which we received from many people, without whose help this symposium would not have been possible. We thank John Bahcall, Jeremiah Ostriker and Lyman Spitzer for their enthusiastic support of our early plans to organize this symposium. We thank Harry Woolf and the Institute for Advanced Study for their hospitality. We thank Mary Wisnovsky, the conference coordinator, for her administrative expertise and enthusiastic support. We thank all the participants for their contributions, and especially the panel members who were rounded up at the last moment to give their impromptu comments. We thank Jens Verner Villumsen and Robert Lupton for their efficient and smooth organization of local affairs, scientifically and culturally. We thank Nels Anderson, Web Ewell, Steve Ratcliff and Tom Statler for their untiring operation of audiovisual aids. We thank Donald LyndenBell, Stuart Shapiro and Lyman Spitzer for supplying us with copies of originals and translations of the material in the first two appendices. The first appendix has been translated by Ludmilla Wightman, whose cheerful help we happily acknowledge. The second appendix is a revision by Ludmilla Wightman of a translation by the British Admirality Translation Service. We thank Ron Webb ink and Floor van Leeuwen for delivering custom-made appendices, number three and four, respectively, on short notice. We thank Grace Rapp, Marge Barbosa and Barbara Pinkham for their indefatigable assistance in the various stages of organizing the symposium and preparing these proceedings. Finally we express our thanks to the California Institute for Technology and especially to the Institute for Advanced Study, for bearing the expenses of both com-
xiv PREFACE
puter time and secretarial assistance needed for the preparation of these proceedings.
The members of the Scientific and Local Organizing Committees are listed below. We are grateful to them for their contribution to the success of this symposium.
Scientific Organizing Committee:
T.A. Agekian, K.C. Freeman, D.C. Heggie, P. Hut (Chairman), S. lnagaki, I.R. King, L.M. Ozernoy, L. Spitzer, J. Stodolkiewicz, R. Wielen.
Local Organizing Committee:
J.N. Bahcall, R. Lupton, J.V. Villumsen (Chairman), M. Wisnovsky.
The Editors,
Jeremy Goodman & Piet Hut
xvi
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LIST OF PARTICIPANTS
Aarseth, 3. J. Adler, D. S. Aguilar, 1. A. Anderson, N. Applegate, J.
Auriere, M. Bahcall, J. N. Bahcall, N. A. Barnes, J. Beichman, C.
Bettwieser, E. Casertano, S. Cohn, H. Colin, J. Cudworth, K.
Da Costa, G. S. Dagan, E. Davoust, E Des Forets, G. Djorgovski, S.
Dones, L. Duncan, M. J. Ewell, M. Fall, S. M. Freeman, K. C.
Frenk, C. S. Giannone, G. Gilden, D. Godwin, P. Goodman, J.
Grindlay, J. Gunn, J. E. Hanes, D.A. Harris, W. E. Heggie, D.C.
Cambridge, England, U.K. Charlottesville, VA, U.S.A. Berkeley, CA, U.S.A. Princeton, NJ, U.S.A. Pasadena, CA, U.S.A.
Observatorie du Pic du Midi, France Princeton, NJ, U.S.A. Baltimore, MD, U.S.A. Berkeley, CA, U.S.A. Pasadena, CA, U.S.A.
Gottingen, Germany Princeton, NJ, U.S.A. Bloomington, IN, U.S.A. Besancon, France Williams Bay, WI, U.S.A.
New Haven, CT, U.S.A. Jerusalem, Israel Besancon, France Paris: France Berkeley, CA, U.S.A.
Berkeley, CA, U.S.A. Scarborough, Ontario, Canada Princeton, NJ, U.S.A. Cambridge, England, U.K. Canberra, Australia
Santa Barbara, CA, U.S.A. Palermo, Italy Princeton, NJ, U.S.A. Edinburgh, Scotland, U.K. Pasadena, CA, U.S.A.
Cambridge, MA, U.S.A. Princeton, NJ, U.S.A. Kingston, Ontario, Canada Hamilton, Ontario, Canada Edinburgh, Scotland, U.K.
xx
Hut, P. Inagaki, S. Ipser, J. R. Jarvis, B. Jernigan, J. G.
Jog, C. J. Kandrup, H. E. King, 1. R. Kylafis, N. Lachieze-Rey, M.
Lake, G. R. Larson, R. B. Latham, D. Leonard, P. J. T. Lightman, A. P.
Lo Cascio, L. Lugger, P. Lupton, R. Luwel, M. Mamon, G.
Margulis, M. Mathieu, R. D. Mayor, M. McMillan, S. Meylan,G.
Mikkola, S. Moffat, A. Ostriker, J. P. Peterson, C. J. Phinney, E. S.
Pryor, C. P. Radhakrishnan, V.
Ratcliff, S. Ratnatunga, K. Schommer, R. A.
Seitzer, P. Semenzato, R. Severne, G. Shapiro, S. L. Shara, M.
LIST OF PARTICIPANTS
Princeton, NJ, U.S.A. Kyoto, Japan Gainesville, FL, U.S.A. La Serena, Chile Berkeley, CA, U.S.A.
Princeton, NJ, U.S.A. Austin, TX, U.S.A. Berkeley, CA, U.S.A. Princeton, NJ, U.S.A. Gif-sur-Yvette, France
Murray Hill, NJ, U.S.A. New Haven, CT, U.S.A. Cambridge, MA, U.S.A. Toronto, Ontario, Canada Cambridge, MA, U.S.A.
Palermo, Italy Columbia, MO, U.S.A. Princeton, NJ, U.S.A. Brussel, Belgium Princeton, NJ, U.S.A.
Tucson, AZ, U.S.A. Cambridge, MA, U.S.A. Sauverny, Switzerland Urbana, IL, U.S.A. Sauverny, Switzerland
Turku, Finland Montreal, Quebec, Canada Princeton, NJ, U.S.A. Columbia, MO, U.S.A. Princeton, NJ, U.S.A.
Victoria, BC, Canada Bangalore, India
Princeton, NJ, U.S.A. Princeton, NJ, U.S.A. New Brunswick, NJ, U.S.A.
Tucson, AZ, U.S.A. Padova, Italy Brussel, Belgium Ithaca, NY, U.S.A. Baltimore, MD, U.S.A.
LIST OF PARTICIPANTS
Smith, G. Smith, Jr., H. Spitzer, L. Statler, T. Stodolkiewicz, J.
Sugimoto, D. Sygnet, J. F. Terlevich, E. Toomre, A. Tremaine, S. D.
van Albada, T. van Leeuwen, F. Verter, F. Vi llums en , J. V. Wandel, A. Webb ink , R. F.
White, S. Wielen, R.
Cambridge, MA, U.S.A. Gainesville, FL, U.S.A. Princeton, NJ, U.S.A. Princeton, NJ, U.S.A. Warszawa, Poland
Tokyo, Japan Paris, France
xxi
Hailsham, East Sussex, England, U.K. Cambridge, MA, U.S.A. Cambridge, MA, U.S.A.
Groningen, The Netherlands Hailsham, East Sussex, England, U.K. Troy, NY, U.S.A. Princeton, NJ, U.S.A. Princeton, NJ, U.S.A. Urbana, 1L, U.S.A.
Santa Barbara, CA, U.S.A. Berlin, Germany