WHITE DWARFS
ASTROPHYSICS AND SPACE SCIENCE LIBRARY
VOLUME 214
Executive Committee W. B. BURTON, Sterrewacht, Leiden, The Netherlands
J. M. E. KUIJPERS, Faculty o/Science, Nijmegen, The Netherlands E. P. 1. V AN DEN HEUVEL, Astronomical Institute, University 0/ Amsterdam,
The Netherlands H. V AN DER LAAN, Astronomical Institute, University 0/ Utrecht,
The Netherlands
Editorial Board I. APPENZELLER, Landessternwarte Heidelberg-Konigstuhl, Germany
J. N. BAHCALL, The Institute/or Advanced Study, Princeton, U.S.A. F. BERTOLA, Universita di Padova, Italy
W. B. BURTON, Sterrewacht, Leiden, The Netherlands 1. P. CASSINELLI, University o/Wisconsin, Madison, U.S.A.
C. J. CESARSKY, Centre d'Etudes de Saclay, Gif-sur-Yvette Cedex, France O. ENGVOLD, Institute o/Theoretical Astrophysics, University 0/ Oslo, Norway
J. M. E. KUIJPERS, Faculty o/Science, Nijmegen, The Netherlands R. McCRAY, University o/Colorado, JILA, Boulder, U.S.A.
P. G. MURDIN, Royal Greenwich Observatory, Cambridge, UK F. PACINI, Istituto Astronomia Arcetri, Firenze, Italy
V. RADHAKRISHNAN, Raman Research Institute, Bangalore, India F. H. SHU, University o/California, Berkeley, U.S.A.
B. V. SOMOV, Astronomical Institute, Moscow State University, Russia R. A. SUNY AEV, Space Researchlnstitute, Moscow, Russia
S. TREMAINE, CITA, University o/Toronto, Canada Y. TANAKA, Institute 0/ Space & Astronautical Science, Kanagawa, Japan
E. P. 1. VAN DEN HEUVEL, Astronomical:Institute, University 0/ Amsterdam, The Netherlands
H. VANDER LAAN, Astronomical Institute, University o/Utrecht, The Netherlands
N. O. WEISS, University o/Cambridge, U.K.
WHITE DWARFS Proceedings of the 10th European Workshop on White Dwarfs,
held in Blanes, Spain, 17-21 June 1996
Edited by
J.ISERN Institut d' Estudis Espacials de Catalunya, CSIC,
Barcelona, Spain
M.HERNANZ Institut d' Estudis Espacials de Catalunya, CSIC,
Barcelona, Spain
and
E. GARCIA-BERRO Universitat Politecnica de Catalunya,
Barcelona, Spain
SPRINGER SCIENCE+BUSINESS MEDIA, B.V.
A C.I.P. Catalogue record for this book is available from the Library of Congress
ISBN 978-94-010-6334-0 ISBN 978-94-011-5542-7 (eBook) DOI 10.1007/978-94-011-5542-7
Cover picture: White Dwarf Stars in M4. HST. WFPC2.
PRC95-32. ST Sci opo. August 28, 1995. H Bond (ST Scl), NASA.
Printed on acid-free paper
All Rights Reserved © 1997 Springer Science+Business Media Dordrecht
Originally published by Kluwer Academic Publishers in 1997 Softcover reprint of the hardcover 1st edition 1997
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 copyright owner.
TABLE OF CONTENTS
Preface ................................................................................. xiii
List of Participants ..................................................................... xv
1. Structure and Evolution ...................................................... l
The empirical white dwarf mass-radius relation H. Schmidt ... ........................................................................... 3
What we have learned about white dwarfs from studies of novae S. Starr field .......................................................................... " 11
The redistribution of carbon and oxygen in crystallizing white dwarfs R. Mochkovitch .... ..................................................................... 19
The cooling of white dwarfs and their internal composition M. Salaris, M. Hemanz, J. Isem, 1. Dominguez fj E. Garcia-Berro ..................... 27
Theoretical models of white dwarfs with helium-rich interiors J.M. Aparicio fj G. Fontaine ............................................................ 35
The electrostatic screening of thermonuclear reactions in astrophysical plasmas N.J. Shaviv fj G. Shaviv .... ............................................................ 43
The possible white dwarf-neutron star connection R. Canal fj J. Gutierrez ................................................................ 49
The impact of evolutionary envelope masses on the evolution of white dwarfs T. Blocker, F. Herwig, T. Driebe, H. Bramkamp fj D. Schonbemer ..... ................. 57
The progenitors of high-mass white dwarfs F. Herwig .............................................................................. 63
The multi periodic, short-period variations of WZ Sge J.L. Provencal fj R.E. Nather ........................................................... 67
Limits on gravities of evolved stars, from infrared photometry and binary companions P. Thejll fj A. Ulla ..................................................................... 71
R.otat.ion: CO white dwarfs near the Chandrasekhar limiting mass 1. Dominguez, O. Straniero, A. Tomambe fj J. Isem ... ................................. 75
The Accretion-Induced Collapse of white dwarfs revisited in 3D D. Garda-Senz fj E. Bravo .. ........................................................... 79
vi
II. Luminosity Functions and Populations ................................ 83
Towards a luminosity function of hot DA white dwarfs 1. Liebert, T.A. Fleming, J.B. Holberg, P. Bergeron fj R. Saffer . ........................ 85
White dwarfs in M67 T.A. Fleming, J. Liebert, P. Bergeron fj A. Beauchamp . ................................ 91
Monte Carlo simulations of the kinematics and luminosity function of white dwarfs E. Garcia-Berro fj S. Torres ............................................................ 97
Monte Carlo simulations of the white dwarf population and luminosity function M.A. Wood ............................................................................ 105
Halo white dwarfs: a conservative point of view 1. Is ern, M. Hernanz, E. Garcia-Berro, N. Itoh fj R. Mochkovitch ..................... 113
Halo white dwarfs: a non conventional scenario G. Chabrier, L. Segretain fj D. Mera .............................. ..................... 121
HST observations of white dwarfs in the globular cluster NGC 6397 A.M. Cool, C. Sosin fj I.R. King ....................................................... 129
The distance and age of the globular cluster NGC 6752 measured by HST observations of cluster and field white dwarfs A. Bragaglia, F.R. Ferraro, A. Renzini, R. Gilmozzi, J.B. Holberg, J. Liebert, S. Ortolani, F. Wesemael fj R. Bohlin . ................................................ 135
DA white dwarfs in the Montreal-Cambridge-Tololo survey R. Lamontagne, F. Wesemael, G. Fontaine, S. Demers, P. Bergeron, M.J. Irwin fj w.E. Kunkel. ....................................................................... 143
Cool white dwarf survey using stacked digitised Schmidt plates R. Knox fj M.R.S. Hawkings ........................................................... 149
III. Atmospheres ................................................................ 153
Chemical evolution of cool white dwarf's atmospheres M.T. Ruiz, P. Bergeron fj S.K. Leggett ........ ......................................... 155
The chemical evolution of white dwarf stars: what the observations tell us H.L. Shipman .... ..................................................................... 165
A critical look at the question of thick vs thin hydrogen and helium envelopes in white dwarfs G. Fontaine fj F. Wesemael ........................................................... 173
Polyatomic carbon molecules in very cool helium-rich white dwarfs I. Bues fj T. Asian . ................................................................... 193
Analysis of optical, UV and EUV observations of G 191-B2B B. Wolff, D. Koester fj A. Vidal-Mad jar ............................................... 199
New results on PG 1159 stars and ultrahigh-excitation DO white dwarfs K. Werner, S. Dreizler, U. Heber fj T. Rauch ........ .................................. 207
vii
Non-LTE analyses of DO white dwarfs S. Dreizler & K. Werner ............................................................... 213
New spectral analyses of pre-white dwarfs T. Rauch, S. Dreizler & K. Werner .................................................... 221
The sphericity effects in the NLTE model atmospheres of white dwarfs J. Kubat ............................................................................... 229
Heavy elements in white dwarf envelopes M.A. Barstow, J.B. Holberg, 1. Hubeny & T. Lanz ...................................... 237
Lyman spectra of hot DA white dwarfs D.S. Finley, D. Koester, J. W. Kruk, R.A. Kimble & N.F. Allard ................. ....... 245
Diffusion of silicon in the envelopes of hot DA white dwarfs P. Chayer, G. Fontaine & C. Pelletier .............................. ................... 253
Time-dependent diffusion calculations for hot pre-white dwarfs K. Unglaub & 1. Bues ... ............................................................... 259
Evolutionary calculations of carbon dredge-up in helium envelope white dwarfs J. MacDonald, M. Hernanz & J. Jose ................................. ................. 265
Analysis of optical and ultraviolet spectroscopy of the DAZ white dwarf G 74-7 M. Billeres, F. Wesemael, A. Beauchamp & P. Bergeron ................ ............... 269
Modeling extreme ultraviolet spectra of white dwarfs with high-metallicity LTE models P. Chayer, S. Vennes, J. Dupuis, P. Thejll & A.K. Pmdhan ............................ 273
Extreme ultraviolet spectroscopy of EUVE J0720-317 and EUVE J0723-277 J. Dupuis, S. Vennes & S. Bowyer ..... ................................................ 277
A new dithered EUVE spectrum of PG 1234+482 S. Jordan, D. Koester & D.S. Finley ...... ............ '" .............................. 281
Line of sight H and He ionization fractions in the local interstellar medium P.D. Dobbie & M.A. Barstow .. ........................................................ 285
An instrument for observations of EUV opacity sources in G 191-B2B K. Gunderson, J. Green & R. McLean ................................................. 289
Metals in the variable DA G 29-38 D. Koester, J.L. Provencal & H.L. Shipman ...................... ...................... 293
IV. White Dwarfs in Binaries ........... .................................... 297
In search of the double degenerate progenitors of Type Ia Supernovae R.A. Saffer & M. Livia .... ........................ , ................................... 299
The double degenerate population M. Hernanz, J. Isern & M. Salaris ........................................ ............. 307
White dwarf+M dwarf systems: a new infrared search A. G. Gemma .......................................................................... 315
viii
The EC 14026 stars: a new class of pulsating star D.E. Q'Donoghue, C. Koen, D. Kilkenny, R.S. Stobie, A.E. Lynas-Gray f3 S.D. Kawaler .......... ................................................................ 321
Hot white dwarfs in non-interacting binaries from the ROSAT EUV survey M Burleigh f3 M.A. Barstow . .................................. '" .................... 329
HST observations of AM Canum Venaticorum l.E. Solheim, l.L. Provencal f3 E.M Sion .............................................. 337
Effects of irradiation on the secondary star in a tight binary system, exemplified by AM Canum Venaticorum T.K. Nymark .. ........................................................................ 345
White dwarfs in AM Herculis systems B. T. Giinsicke, K. Beuermann, D.de Martino f3 S. lordan .... ........ " ............... 353
HST synthetic spectral analysis of U Gem in early and late quiescence: a heated white dwarf and accretion belt PH Cheng, E.M Sion, K. Horne, 1. Hubeny, M Huang f3 S.D. Vrtilek ................ 359
WFPC2 observations of Procyon B l.L. Provencal, HL. Shipman, P Wesemael, P. Bergeron, HE. Bond, l. Liebert f3 E.M Sion . .................................. '" .......................... 367
Extreme ultraviolet light curve and phase-resolved spectroscopy of the hot white dwarf in V 471 Tauri J. Dupuis, S. Vennes, P. Chayer, S. Cully f3 T. Rodriguez-Bell .. ..................... , 375
Unique white dwarfs accompanying recycled pulsars MH Van Kerkwijk .................................................................... 383
Merging of different mass ratio white dwarfs: first moments of the 0.4-1.2 M0 case 1. Guerrero, J. Is ern, W. Benz, E. Garcia-Berro f3 R. Mochkovitch .................... 391
V. Magnetic White Dwarfs ................................................... 395
New results of magnetic white dwarf spectroscopy S. Jordan .............................................................................. 397
I-D and 2-D calculations of dynamo-generated magnetic fields in white dwarfs l.A. Markiel, J.H. Thomas f3 H.M. Van, Horn .......................................... 405
Magnetic field survey of DC white dwarfs A. Putney . ............................................................................ 413
New IDE-spectra of the magnetic white dwarf Grw +70°8247 and their interpretation D. Engelhardt f3 1. Bues ........ ....................................................... 421
VI. Pulsating White Dwarfs ................................................. 427
Convection and the ZZ Ceti instability strip D. Koester f3 G. Vauclair .............................................................. 429
ix
WET observations of the DAY variable HL Tau 76: first results N. Dolez fj s.J. Kleinman ............................................................. 437
Preliminary asteroseismology of G 29-38 P. Bradley fj S. J. Kleinman ... ............................................ , ........... 445
Recent advances in the theoretical determination of the ZZ Ceti instability strip P. Brassard fj G. Fontaine ... .......................................................... 451
Cool DAY asteroseismology S.J. Kleinman ... ...................................................................... 459
Overstability of g-modes in ZZ Ceti variables y. Wu ................................................................................. 467
A continuing spectroscopic study of the instability strip of the pulsating DB (Y 777 Her) white dwarfs: the view in the optical F. Wesemael, A. Beauchamp, P. Bergeron, G. Fontaine, R.A. Saffer fj J. Liebert .. ..... 473
The potential of asteroseismology for hot, B sub dwarfs: a new class of pulsating stars? S. Charpinet, G. Fontaine, P. Brassard fj B. Dorman .. ................................ 477
Modeling time-resolved spectra of ZZ Ceti stars H. Viith, D. Koester, S.O. Kepler fj E.L. Robinson ..................................... 481
Discovery of two new ZZ Ceti variables N. Dolez, G. Vauclair, J.N. Fu fj M. Chevreton ..................... , .................. 485
Non-pulsating DA white dwarfs in the DAY region R. Silvotti, C. Bartolini, G. Cosentino, A. Guarnieri fj A. Piccioni .................. ,.489
PREFACE
The study of white dwarfs has been steadily growing during the last years and now is a mature field extending its influence over many others. Since white dwarfs are long lived objects, they can be used to obtain information about the history of the Galaxy. The simplicity of their structures enables them to act as precise particle physics laboratories and the extreme conditions reached at their surfaces allow us to test the equation of state and to study the behavior of matter under conditions impossible to be reached in terrestrial laboratories. Nevertheless, white dwarfs are still challenging astrophysicists. Many questions, ranging from the determination of fundamental parameters to the evolution of their outer layers, are still waiting for a satisfactory answer.
The European Workshop series on White Dwarfs started in 1974 as a consequence of the effort and enthusiasm of Professor Volker Weidemann. The existing proceedings of these meetings, together with those corresponding to the lAU Colloquia held in Rochester (1979) and in Hanover (1988), provide a unique opportunity to follow the development of this field. We hope that the present volume will provide a representative snapshot of the state of the art in 1996. In this sense we are very indebted to all the participants that have sent their contributions according to the instructions (this clearly excludes everybody beyond three sigmas from the standards).
We are very indebted to all of our colleagues of the Scientific Organizing Committee: M. Barstow, F. D'Antona, G. Fontaine, 1. Iben, D. Koester, J. Liebert, R. Mochkovitch, G. Shaviv, P. Thejll, H. Van Horn, and G. Vauclair. We want also to express our recognition to Carme Arenillas, Pilar Camps and Evilio del Rio for their enthusiastic support. We are specially grateful to our colleagues at the Centre d'Estudis Avanyats de Blanes for their support anf for showing us that not all in science is Astrophysics. We also thank the Consell Comarcal de la Selva for logistic support and the Blanes City Hall for their hospitality. Finally we acknowledge the financial support received from the Direcci6n General de Investigaci6n Cientifica y Tecnica (D.G.I.C.Y.T.), the Comissi6 Interdepertamental de Recerca i In-
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xiv
novaci6 Tecnologia (C.I.R.I.T.), the Consejo Superior de Investigaciones Cientificas (C.S.I.C.), the Universitat Politecnica de Catalunya (U.P.C.) and the Fundaci6 Catalana per a la Recerca (F.C.R.).
Barcelona, January 1997
Jordi Isern and Margarida Hernanz Institut d'Estudis Espacials de Catalunya
(C.S.I.C. Research Unit)
Enrique Garcia-Berro Universitat Politecnica de Catalunya
List of Participants
xvi
D. ALVAREZ, (64)
F. ALLARD, (28)
J.M. APARICIO, (67)
M.A. BARSTOW, ( 2)
T. BLOCKER, (52)
P.A. BRADLEY, (46)
A. BRAGAGLlA, (59)
P. BRASSARD, (61)
I. BUES, (58)
Dept. d'Astronomia i Meteorologia, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona, SPAIN e-mail: [email protected]
Dept. of Physics, Wichita State UniversitY,1845 Fairmount, Wichita KS 67260-0032, USA e-mail: [email protected]
Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec, CANADA H3C 3J7 e-mail: [email protected]
Dept. of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH, UK e-mail: [email protected]. uk
Astrophysikalisches Institut Potsdam, Telegrafenberg A27, 0-14473 Potsdam, GERMANY e-mail: [email protected]
Los Alamos National Laboratory, XTA MS B220, Los Alamos NM 87545, USA e-mail: [email protected]
Osservatorio Astronomico di Bologna, Via Zamboni 33,1-40126 Bologna, ITALY e-mail: [email protected]
Dept. de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec, CANADA H3C 3J7 e-mail: [email protected]
Astronomisches Institut der Universitaet Erlangen, Remeis-Sternwarte Bamberg, Sternwartstrasse 7, 0-96049 Bamberg, GERMANY e-mail: [email protected]
M. BURLEIGH, (49)
R. CANAL, (31)
AM. COOL, (16)
L. CUCURULL, ( 7)
G. CHABRIER, (32)
P. CHAYER, (25)
P.O. DOBBIE, (57)
N. DOLEZ, (10)
I. DOMiNGUEZ, (
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Physics and Astronomy Department, University of Leicester, Leicester LE1 7RH, UK e-mail: [email protected]
Dept. d'Astronomia i Meteorologia, Universitat de Barcelona, Av. Diagonal, 647, 08028 Barcelona, SPAIN e-mail: [email protected]
Astronomy Department, University of California, 601 Campbell Hall, Berkeley, CA 94720-3411, USA e-mail: [email protected]
IEEC, Edifici Nexus -104, Gran Capita 2-4,08034 Barcelona, SPAIN e-mail: [email protected]
Laboratoire de Physique, Ecole Normale Superieure de Lyon, 46 Allee d'italie, 69364 Lyon Cedex 07, FRANCE e-mail: [email protected]
Center for EUV Astronphysics, 2150 Kitteredge Street, Berkeley, California 94720, USA e-mail: [email protected]
X-Ray Astronomy Group, Dept. of Physics and Astronomy, University of Leicester, University Road, Leicester, LE17RH, UK e-mail: [email protected]
Observatoire Midi-Pyrenees, 14 Avenue Edouard Belin, 31400 Toulouse, FRANCE e-mail: [email protected]
Fisica te6rica y del cosmos, Universidad de Granada, c/ Fuentenueva 18002, Granada, SPAIN e-mail: [email protected]
xviii
S. DREIZLER, (24)
J. DUPUIS, (14)
D.S. FINLEY, (38)
TA FLEMING, (36)
G. FONTAINE, (8)
B.T. GANSICKE, (15)
Institut fOr Astronomie und Astrophysik, Universitat Kiel, 0-24098 Kiel, GERMANY e-mail: [email protected]
Center for EUV Astrophysics, 2150 Kittredge Street, Berkeley CA 94720, USA e-mail: [email protected]
Eureka Scientific, Inc, 2452 Delmer St., Oakland CA 94602, USA e-mail: [email protected]
University of Arizona, Steward Observatory, Tucson, AZ 85721, USA e-mail: [email protected]
Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, Quebec, CANADA H3C 3J7 e-mail: [email protected]
Universitats-Sternwarte G6ttingen, Geismarlandstrasse 11, 0-37083 G6ttingen, GERMANY e-mail: [email protected]
E. GARCiA-BERRO, (6) Dept. de Ffsica Aplicada, Universitat Politecnica de Catalunya, Jordi Girona sIn, M6dul B-4, 08034 Barcelona, SPAIN e-mail: [email protected]
D. GARCIA-SENZ, (60) Universitat Politecnica de Catalunya, Dept. Ffsica i Enginyeria Nuclear, UPC - Campus Nord, Sor Eulalia de Anzizu sIn - MOd. 84, 08034 Barcelona, SPAIN
A. GEMMO, (12)
e-mail: [email protected]
Dipartimento di Astronomia, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio,5, 1-35122 Padova ITALY e-mail: [email protected]
xix
J. G6MEZ, ( ) IEEC, Edifici Nexus - 104, Gran Capita 2-4, 08034 Barcelona, SPAIN e-mail: [email protected]
J. GREEN, (66) CAS A, University of Colorado, 1255 38th Street -Campus Box 593, Boulder, Colorado 80309, USA e-mail: [email protected]
J. GUERRERO, (54) IEEC, Edifici Nexus -104, Gran Capita 2-4, 08034 Barcelona, SPAIN e-mail: [email protected]
K. GUNDERSON, (68) Astrophysics Research Laboratory, University of Colorado, 1255 38th Street, Boulder, CO 80303, USA
J. GUTIERREZ, (63)
M. HERNANZ, (18)
F. HERWIG, (43)
J.B. HOLBERG, (39)
I. IBEN, (21)
J. ISERN, ( 1)
e-mail: [email protected]
Dept. d'Astronomia i Meteorologia, Universitat de Barcelona, Marti i Franques, 1, 08028 Barcelona, SPAIN e-mail: [email protected]
IEEC, Edifici Nexus - 104, Gran Capita 2-4, 08034 Barcelona, SPAIN e-mail: [email protected]
Astrophysikalisches Institut Potsdam, Telegraphenberg A 27, D-14473 Potsdam, GERMANY e-mail: [email protected]
Lunar and Planetary Laboratory-west, University of Arizona, Gould-Simpson Building, Tucson AZ 85721, USA e-mail: [email protected]
Astronomy Department, University of Illinois, 1002 West Green St., URBANA, IL 61801, USA e-mail: [email protected]
IEEC, Edifici Nexus -104, Gran Capita 2-4,08034 Barcelona, SPAIN
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S. JORDAN, (44)
S. KAWALER, (34)
I. R. KING, ( 9)
S.J. KLEINMAN, (33)
R. KNOX, (47)
D. KOESTER, (29)
J. KUBAT, (40)
e-mail: [email protected]
Institut fOr Astronomie und Astrophysik, Universitat Kiel, 0- 24098 Kiel, GERMANY e-mail: [email protected]
Dept. of Physics and Astronomy, Iowa State University, Ames IA 50011, USA e-mail: [email protected]
Astronomy Department, University of California, Berkeley, CA 94720-3411, USA e-mail: [email protected]
Astronomy Dept., University of Texas, Austin, TX 78712, USA e-mail: [email protected]
Institute of Astronomy, University of Edinburgh Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK e-mail: [email protected]
Institut fOr Astronomie und Astrophysik, Universitat Kiel, 0-24098 Kiel, GERMANY e-mail: [email protected]
Astronomicky ustav, Akademie ved Ceske Republiky, Fricova 1, 251 65 Ondrejov, CZECH REPUBLIC e-mail: [email protected]
R. LAMONTAGNE, (30) Departement de Physique, Universite de Montreal, C.P. 6128, Succ. Centre-ville, Montreal, Quebec, CANADA H3C 3J7
J. LIEBERT, ( 3)
e-mail: [email protected]
University of Arizona, Steward Observatory, Tucson, AZ 85721, USA e-mail: [email protected]
JA MARKIEL, (42) Dept. of Physics and Astronomy, University of Rochester, Rochester, NY 14627, USA e-mail: [email protected]
xxi
C. MASSACAND, (23) IMR - Nordlysobservatoriet, University of Tromso, N-9037 Tromso, NORWAY e-mail: [email protected]
R. McLEAN, (70) CASA, University of Colorado, Boulder, ARLl1255 38th St., Boulder, CO, USA e-mail: [email protected]
R. MOCHKOVITCH, (41) C N R S, Institut d'Astrophysique de Paris, 98 bis, Blvd. Arago, 75014 Paris, FRANCE e-mail: [email protected]
T.K. NYMARK, (17) The Auroral Observatory, University of Tromso, 9037 Tromso, NORWAY e-mail: [email protected]
D. O'DONOGHUE, (19) Dept. of Astronomy, University of Cape Town, Rondebosch 7700, Cape Town, SOUTH AFRICA e-mail: [email protected]
J. PROVENCAL, (26) Dept. of Physics and Astronomy, University of Delaware, Newark, DE 19716, USA e-mail: [email protected]
A. PUTNEY, (11) California Institute ofTechnology, 105-24, Pasadena, CA 91125, USA e-mail: [email protected]
T. RAUCH, (45) Institut fOr Astronomie und Astrophysik, Universitat Kiel, D-24098 Kiel, GERMANY e-mail: [email protected]
M.T. RUIZ, (27) Department of Astronomy, Universidad de Chile, Casilla 36-D, Santiago, CHILE e-mail: [email protected]
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P. RUIZ-LAPUENTE. (35) Dept. Astronomia i Meteorologia. Universitat de Barcelona. Diagonal 647. 08028 Barcelona. SPAIN e-mail: [email protected]
R.A. SAFFER. (51)
M. SALARIS. (65)
H. SCHMIDT. (50)
G. SHAVIV. (22)
Space Telescope Science Institute. 3700 San Martin Drive. Baltimore MD 21218. USA e-mail: [email protected]
IEEC. Edifici Nexus - 104. Gran Capita 2-4. 08034 Barcelona. SPAIN e-mail: [email protected]
Institut fOr Astronomie und Astrophysik. Universitat Kiel. D- 24098 Kiel. GERMANY e-mail: [email protected]
Asher Space Research Institute and Dept. of Physics. Israel Institute of Technology. Haifa. ISRAEL 32000 e-mail: [email protected]
H. SHIPMAN. (4) Physics and Astronomy Department University of Delaware Sharp Laboratory Newark - Delaware 19716 USA e-mail: [email protected]
E.M. SION. ( ) Dept. of Astronomy and Astrophysics Villanova University Villanova. PA 19085 USA e-mail: [email protected]
J.E. SOLHEIM. (56) Institute of Mathematical and Physical Sciences University of Tromso Auroral Observatory N-9037 Tromso NORWAY a-mail: [email protected]
S. STARRFIELD. (13) Physics & Astronomy Arizona State University P.O Box 871504 Tempe. AZ 85287-1504 USA e-mail: [email protected]
S. TORRES.( ) Universitat Politecnica de Catalunya EUP Matar6 Av. Puig i Cadafalch. 101-111 08303 MATAR6 e-mail: [email protected]
A. ULLA, ( )
K. UNGLAUB, (62)
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Instituto de Astroflsica de Canarias cl Via Lactea sIn 38200 La Laguna SPAIN e-mail: [email protected]
Astronomisches Institut der Universitaet Erlangen Remeis-Sternwarte Bamberg Sternwartstrasse 7 0-96049 Bamberg GERMANY e-mail: [email protected]
M. VAN KERKWIJK, (69) Dept. of Astronomy, m.s. 105-24 California Institute ofTechnology Pasadena, CA 91125 USA e-mail: [email protected]
H. VATH, (48)
V. WEIDEMANN, (20)
F. WESEMAEL, (53)
B. WOLFF, ( 5)
M. WOOD, (55)
Y. WU, (37)
Institut fOr Astronomie und Astrophysik Universitat Kiel 0-24098 Kiel GERMANY e-mail: [email protected]
Institut fOr Astronomie und Astrophysik Universitat Kiel 0-24098 Kiel GERMANY e-mail: [email protected]
Oepartement de Physique Universite de Montreal C.P. 6128, Succ. Centre-Ville Montreal - QUEBEC CANADA H3C 3J7 e-mail: [email protected]
Institut fOr Astronomie und Astrophysik Universitat Kiel 0-24098 Kiel GERMANY e-mail: [email protected]
Dept. Physics and Space Sciences Florida Institute of Technology 150. W. University Blvd. Melbourne, FL 32901-6988 USA e-mail: [email protected]
Theoretical Astrophysics, 130-33 California Institute of Technology Pasadena, CA 91125 USA e-mail: [email protected]