ESO ASTROPHYSICS SYMPOSIA European Southern Observatory

Series Editor: Philippe Crane

Springer-Verlag Berlin Heidelberg GmbH

Hans Ulrich Kaufl Ralf Siebenmorgen (Eds.)

The Role of Dust in the Formation of Stars

Proceedings of the ESO Workshop Held at Garching, Germany, 11-14 September 1995

Springer

Volume Editors

Hans Ulrich Kaufl European Southern Observatory Karl-Schwarzschild-Strasse 2 D-85748 Garching, Germany

Ralf Siebenmorgen ESA Villafranca del Castillo Satellite Tracking Station P.O. Box 50727 E-28080 Madrid, Spain

Series Editor

Philippe Crane European Southern Observatory Karl-Schwarzschild-Strasse 2 D-85748 Garching, Germany

Cataloging-in-Publication Data applied for

Die Deutsche Bibliothek - CIP-Einheitsaufnahme

The role of dust in the formation of stars: Proceedings of the ESO workshop, held at Garching, Germany, 11-14 September 19951 Hans Ulrich Kiiufl ; Ralf Siebenmorgen (ed.).-Berlin; Heidelberg; New York; Barcelona; Budapest; Hong Kong; London; Milan; Paris; Santa Clara; Singapore; Tokyo: Springer, 1996 (ESO astrophysics symposia)

NE: Kiiufl, Hans Ulrich [Hrsg.]; European Southern Observatory

ISBN 978-3-662-22515-8 ISBN 978-3-540-68594-4 (eBook) DOl 10.1007/978-3-540-68594-4

This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, re-use of illustrations, recitation, broadcasting, reproduction on microfilms or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer-Verlag. Violations are liable for prosecution under the German Copyright Law. © Springer-Verlag Berlin Heidelberg 1996 Originally published by Springer-Verlag Berlin Heidelberg New York in 1996. Softcover reprint of the hardcover 1 st edition 1996

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Typesetting: Camera ready by authors/editors SPIN: 10517774 55/3142-543210 - Printed on acid-free paper

Preface

This ESO workshop, which took place in September 1995 on a topic that at a first glance could be considered rather specialized, attracted an unpre-dictably large number of scientists. This certainly reflects the importance of this field, which has lost its seemingly esoteric character, in a wider astro-physical context.

To give as much room as possible in these proceedings to the targeted talks, no presentation of the Very Large Telescope Observatory has been included. All readers missing such a presentation are reminded that up-to-date in-depth information about the VLT status is available electronically.1

Papers were given concerning observations in the entire electromagnetic spectrum from x-rays to mm-waves, i.e., exceeding 22 octaves in frequency. The VLT as any ground-based optical observatory can only address at best 7 octaves. Nevertheless the VLT, most likely the only ground-based observa-tory specifically designed to access all these 7 octaves of the electromagnetic spectrum practically in parallel, will undoubtedly be a tool of extreme value to this field.

This workshop took place only days before ISO, Europe's Infrared Space Observatory, was successfully launched. In its lifetime, which apparently will substantially exceed all expectations, ISO will undoubtedly make important observations (and discoveries!) in this field. Combining data from ISO and the VLT, two extremely complementary observatories, will greatly enhance the understanding of star formation. It is of particular advantage that the VLT is located in the southern hemisphere, because this is the part in the sky where most galactic star forming regions are located. Moreover the VLT will allow for in-depth studies of star formation in the Magellanic Clouds. The influence of metallicity (i.e., dust abundance and composition) on star for-mation can hence be tested. This workshop demonstrated that the improved observational capabilities are well complemented by progress in the fields of numerical simulation and laboratory experiments. Talks were given on how magnetic fields reign the protostellar collaps and on grain-grain interaction, and there was also a demonstration of a model-model collision.

At this point the editors wish to thank the scientific organizing commit-tee and all participants and authors. Our thanks go also to all ESO staff contributing to this conference in general, but especially to the conference secretary Christina Stoffer.

Garching/Vilspa, June 1996

1 http://http.hq.eso.org/vlt/

Hans Ulrich Kaufl Ralf Siebenmorgen

Contents

Part I Ground-Based Observations of Young Stellar Objects

High-Angular Resolution Near-Infrared Observations of the Circumstellar Environment of Young Stellar Objects N. Ageorges and A. Eckart ............................................. 3

Submillimeter Dust Continuum Emission as a Probe of Protostellar Evolution P. Andre and S. Bontemps ............................................. 7

Compact Molecular Outflows from Young Stellar Objects in L1641 J .C. Correia, M. Griffin, P. Saraceno, and A. Zavagno .................. 11

Anatomy of a Spatially Resolved Dust Disc Around a B-Type YSO W.R.F. Dent, C. Racela, and F. Rosengarten .......................... 15

Mid-IR PAH Emission in YSOs WL 16 & WL 22 J.P. Emerson .......................................................... 19

Mid-IR Imaging of YSOs: the Hydrocarbon Emission Features in WL 16 J.P. Emerson, T.J.T. Moore, C.J. Skinner, and M.M. Meixner ... . ..... 23

Star Formation in the Vela Molecular Clouds: Near IR Images T. Giannini, D. Lorenzetti, B. Nisini, L. Spinoglio, A. Zavagno, R. Liseau, P. Andreani, and A. Moneti ................................ 27

Linear and Circular Imaging Polarimetry of the Chamaeleon Infrared Nebula T.M. Gledhill, A. Chrysostomou, and J .H. Hough ...................... 31

Near-IR Speckle Imaging of Luminous Young Stellar Objects M.G. Hoare, A. Glindemann, and A. Richichi .......................... 35

VIII

A Large Dust Shell Observed at 10j.lm Around V921 Sco P.-O. Lagage, S. Cabrit, T. Montmerle, and G. Olofsson ............... 39

Dust Emission from Bok Globules R. Launhardt and T. Henning ......................................... 43

Density Structure of Protostellar Envelopes F. Motte, P. Andre, and R. Neri ....................................... 47

What Causes the Variability of the PV Cep Nebula? T. Neckel and H.J. Staude ............................................. 51

1.3 mm Dust Continuum Observations of Young X-Ray Selected Stars in Ophiuchus D. Nurnberger, W. Brandner, H.W. Yorke, and H. Zinnecker ........... 55

The Luminosity-mm Flux Correlation of Class I Sources Exciting Outflows P. Saraceno, F. D'Antona, F. Palla, M. Griffin, and E. Tommasi 59

PAHs as Probes of Photo-Dissociation Regions in M17 and the Orion Bar G.C. Sloan, J. Bregman, A.S.B. Schultz, P. Temi, and D.M. Rank ...... 63

Mid-Infrared Imaging Polarimetry of BNKL C.H. Smith, D.K. Aitken, T.J .T. Moore, T. Fujiyoshi, P.F. Roche, and C.M. Wright .......................................... 67

Star Formation in the Northern Region of NGC 6334 M. Tapia and P. Persi ................................................. 71

Morphology of the Star Forming Region Associated with HH25-26 E. Tommasi, D. Lorenzetti, and B. Nisini .............................. 75

New Millimetre Observations of Pre-stellar Cores D. Ward-Thompson, P. Andre, and F. Motte .......................... 79

Young Stellar Objects in L1641: a Submillimeter Continuum Study A. Zavagno, S. Molinari, E. Tommasi, P. Saraceno, and M. Griffin ..... 83

Part II Observations of Dust Factories

3-D Structure of the Bipolar Dust Shell of TJ Carinae D.G. Currie, D.M. Dowling, E.J. Shaya, J.J. Hester, The HST WF fPC Instrument Definition Team, and

IX

The HST WFPC2 Instrument Definition Team ........................ 89

Dust Around Post-AGB Sources with 21 J.lm Feature R. Szczerba, K. Volk, and S. Kwok .................................... 95

Part III Observational Results Based on IRAS, COBE or Balloon Borne Platforms

HIRES IRAS Images of the Serpens Core M. Barsony and R.L. Hurt ........................................... 101

A Catalogue of Massive Young Stellar Objects: A Description S.J. Chan and T. Henning ............................................ 105

The S135 Star Formation Region C. Kampe and G. Joncas ............................................. 109

Star Formation in the Cepheus Flare Molecular Clouds M. Kun .............................................................. 113

An Overview of the COBE Infrared Datasets D. Leisawitz ......................................................... 117

Submillimeter Continuum Emission in the Orion A Cloud Observed with PRONAOS I. Ristorcelli, A. De Luca, M. Giard, F. Pajot, J.P. Torre, G. Serra, and J.M. Lamarre .......................................... 121

Catalogue of IRAS Loops in the lInd Galactic Quadrant L.V. T6th, C. Kiss, and A. Mo6r ..................................... 125

Triggered Core Formation in Nearby Clouds L.V. T6th and A. Horvath ........................................... 129

Searching for New Young Stars in the IRAS Point Source Catalog H.J. Walker, T.L. Lim, B.M. Swinyard, P.J. Richards, and R.J. Emery 133

x

Part IV Vega-Type, T-Tauri, ). Bootis and Herbig Ae/Be Stars

Vega-Type Systems P. Artymowicz ....................................................... 137

Far-Infrared Spatial Observations of Herbig Ae/Be Stars and Low Mass Stars H.M. Butner ......................................................... 149

A Boo Stars in the Orion OBl Association M. Gerbaldi and R. Faraggiana ....................................... 157

Comets as a Source of the Dust in the f3 Pictoris Disk J .M. Greenberg and A. Li ............................................ 161

Magnetic Fields of T Tauri Stars E.W. Guenther and J.P. Emerson .................................... 175

Lambda Bootis Stars and 'Dusty' A Stars H. Holweger and I. Rentzsch-Holm ................................... 179

Modelling of the IR Intensity Maps for HAEBE Stars with Algol-Like Minima V. Il'in, N. Krivova, and A. Men'shchikov ............................ 183

Multiwavelength Study of HAEBE Stars with Algol-Like Minima N. Krivova and V. Il'in ............................................... 187

Investigating the Circumstellar Morphology of Herbig Ae/Be Stars D. Lorenzetti, B. Nisini, S. Pezzuto, F. Strafella, and F. Berrilli 191

Coronographic Search for Dust Around Main Sequence Stars D. Mouillet, A.-M. Lagrange, and J.-L. Beuzit ........................ 195

First Results of a Spectropolarimetric Survey of Herbig Ae/Be Candidates R.D. Oudmaijer and J .E. Drew ....................................... 199

Forbidden Emission Lines in the Winds of Classical T Tauri Stars G. Paatz and M. Camenzind ......................................... 203

XI

Composition and Distribution of Dust in the ,B-Pictoris Disk E. Pantin and P.-O. Lagage .......................................... 207

Observations of Binaries and Envelopes in Herbig Ae/Be Stars A. Richichi and C. Leinert ........................................... 211

Dust Shells Around Herbig Ae/Be Stars N.V. Voshchinnikov .................................................. 215

Silicate Dust Around ,B-Pic-Like Stars H.J. Walker, H.M. Butner, D. Wooden, and F. Witteborn ............. 223

Part V Properties of Dust Around Young Stellar Objects

Grain Properties in Different Phases of the Interstellar Medium G. Barbaro, A. Di Bartolomeo, P. Patriarchi, and M. Perinotto 229

A Molecular Conglomerate Model of Small Interstellar Dust F.O. Clark, R.F. Shipman, R. Assendorp, D. Kester, and M.P. Egan 233

On the Stability of Dust Aggregates in Collisions C. Dominik and A.G.G.M. Tielens ................................... 237

Dust in the Environment of YSOs A. Evans ............................................................. 241

Dust Opacities for Molecular Cloud Cores and Protoplanetary Accretion Disks T. Henning .......................................................... 250

On the Absence of Diffuse Band Carriers in Opaque Circumstellar Disks J. Krelowski and W. Wegner ......................................... 258

Dust in Protostellar Cores E. Krugel and R. Siebenmorgen ...................................... 262

XII

The Composition and Distribution of Dust in Galactic H II Regions R.F. Shipman and F.O. Clark .................. . ..................... 268

The Effects of Clumping on Calculated Grain Properties R.F. Shipman ........................................................ 272

Signature of the Dust Composition Towards Herbig-Haro Energy Sources R. Sieben morgen , R. Gredel, and J.-L. Starck ......................... 276

The Composition of Interstellar Dust A.G.G.M. Tielens .................................................... 280

The Shape of the Extinction Curve of Opaque Circumstellar Matter W. Wegner and J. Krelowski ......................................... 288

Modelling of Interstellar Extinction in Single Clouds U sing the Method of Regularisation V.G. Zubko, J. Krelowski, and W. Wegner ............................ 291

Part VI Ices and Laboratory Studies

Laboratory Studies of Electric Charging of Dust Particles I. Cermak, E. Griin, and J. Svestka ................................... 297

Solid State Infrared Features: a Diagnostic Tool for Chemical Interactions Between Interstellar Gas and Grains L. d'Hendecourt and P. Ehrenfreund ................................. 301

Infrared Properties of Isolated Water Ice P. Ehrenfreund, W.A. Schutte, and P. Gerakines ...................... 309

Nitrogen-Bearing Organic Molecules in Hot Cores M.E. Kress and S.B. Charnley ........................................ 313

UV Irradiation of Small Carbon Grains V. Mennella, L. Colangeli, P. Palumbo, A. Rotundi, W. Schutte, and E. Bussoletti ........................................ 317

Laboratory Experiments on CO and CO2 Ices M.E. Palumbo and G. Strazzulla ..................................... 321

Formaldehyde and Methanol Dominated Ices Toward GL 2136 W.A. Schutte, P.A. Gerakines, T.R. Geballe, E.F. van Dishoeck,

XIII

and J .M. Greenberg .................................................. 325

Ice Cocktails in Molecular Cloud Cores T.C. Teixeira, J.P. Emerson, and F.P. Pijpers

Optical Constants of Amorphous Carbon Extracted from Recent Laboratory Extinction Measurements

329

V.G. Zubko, V. Mennella, L. Colangeli, and E. Bussoletti ............. 333

Part VII Radiative Transfer

Radiative Transfer Models of Far-IR from W3 IRS 4 and IRS 5 M.F. Campbell, H.M. Butner, P.M. Harvey, N.J. Evans, II, M.B. Campbell, and C.N. Sabbey .................................... 339

Models of Dusty Disks Including Transiently Heated Particles A. Efstathiou and R. Siebenmorgen .................................. 343

Infrared Classification of Young Stellar Objects Z. Ivezic and M. Elitzur .............................................. 347

2D Radiative Transfer Models of the Embedded YSOs HL Tau and L1551 IRS 5: What Is Inside? A. Men'shchikov and T. Henning ..................................... 351

3D Continuum Radiative Transfer J. Steinacker and T. Henning ......................................... 355

Part VIII Dust as a Catalytic Agent for Star Formation

Evolution of the Molecular Abundance in Protoplanetary Disks Y. Aikawa, S.M. Miyama, T. Nakano, and T. Umebayashi ............ 363

Magnetic Fields, Interstellar Dust, UV Radiation and Star Formation G.E. Ciolek .......................................................... 367

XIV

Ambipolar Diffusion and Interstellar Chemistry M.P. Egan and S.B. Charnley ........................................ 373

Simulating Dusty Gas Using SPH S.T. Maddison and J.J. Monaghan ................................... 377

Role of Dust in Protostar Formation T.C. Mouschovias .................................................... 382

The Role of Dust in the Dissipation of Magnetic Fields in Molecular Clouds T. Nakano, R. Nishi, and T. Umebayashi ............................. 393

The Effects of Gas-Grain Interactions on Protostellar Line Profiles J .M.C. Rawlings ..................................................... 401

Chemistry in Molecular Clouds Without and with Dust Coagulation R.M. Sablotny and T. Henning ....................................... 405

Part IX Miscellaneous

Optically Thick Main Sequence Evolution for Still Accreting Massive Stars P.A. Bernasconi ...................................................... 411

Dynamical Aspects of Dust Radiation Interaction Around Young Stars N. Berruyer, B. Lopez, and J.-P.J. Lafon ............................. 415

The Dust Size Distribution and Grain Shattering in Shock Waves A.P. Jones, A.G.G.M. Tielens, D.J. Hollenbach, and C.F. McKee ..... 419

Dust Grain Processing: A New Computational Method Applied to a Protostellar Accretion Shock D. Kruger, A.B.C. Patzer, and E. Sedlmayr ........................... 423

Electrical Charging of Dust: A Review J .-P.J. Lafon ........................................... . ............. 427

Dust as a Tool to Study the Neutral Outflows from Luminous YSOs

xv

H.J. Staude and T. Neckel ........................................... 435

The Distribution of CS and NH3 in Star-Forming Regions S.D. Taylor, O. Morata, and D.A. Williams ......................... " 436

Low Mass Star Formation in Globular Filaments: Evidence from Dust and Molecular Line Emission H. Wiesemeyer, R. Gusten, R. Zylka, D. Fiebig, and M.C.H. Wright " 440

Part X Concluding Remarks

Conference Summary C. Waelkens ......................................................... 447

Author Index ...................................................... 451

Subject Index.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 454

Source Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 457

Index of Molecules ................................................ 461

List of Participants

Fred ADAMS adams

XVIII

University of California, Berkeley, Radio Astronomy Laboratory

Luigi COLANGELI colangeliClastrna.na.astro.it Osservatorio Astronomico di Capodimonte

Jose Carlos CORREIA j . c. correiaClqmw. ac. uk Queen Mary and Westfield College, London

Pierre COX Obs. de Marseille

p427coxClmpifr-bonn.mpg.de and coxClobmara.cnrs-mrs.fr

Douglas CURRIE currieClkhaos . umd. edu University of Maryland, Dept. of Physics

Louis d 'HEND ECO URT IdhCliaslab. ias . fr Institut d'Astrophysique Spatiale - CNRS, Orsay

John DANZIGER jdanzigeCleso.org ESO, Garching

Emmanuel DARTOIS dartoisClias . fr Institut d'Astrophysique Spatiale - CNRS, Orsay

William DENT dentCljach.hawaii. edu Joint Astronomy Centre, Hilo

Carsten DOMINIK dominikClstrw .leidenuniv .nl Leiden University Observatory

Michael EGAN eganClpldac . plh. af . mil Phillips Laboratory, Geophysics Directorate

Pascale EHRENFREUND pascaleClstrwchem. strw . LeidenUni v . nl Leiden University Observatory

James EMERSON j .p.emersonClqmw.ac.uk Queen Mary and Westfield College, London

N ye EVANS aeClastro. keele . ac . uk Keele University, Department of Physics

Michele G ERBALDI gerbaldiCliap. fr Institut d' Astrophysique, Paris

Teresa GIANNINI teresaClsunir. ifsi. fra. cnr. it IFSI - CNR, Frascati

Philippe GIOVANETTI giovaClcesr. cnes. fr C.E.S.R., Toulouse

Tim GLEDHILL tmgClstar . herts . ac . uk University of Hertfordshire, Dept. of Physical Sciences

Mayo GREENBERG mayoClrulhl1.1eidenuniv.nl Leiden University, Astrophysics Lab.

Eike GUENTHER e. guentherClqmw. ac. uk Queen Mary and Westfield College, London

XIX

Thomas HAYWARD hayward

xx

IFSI - CNR, Frascati

Sarah MADDISON maddisonClhypatia.maths .monash. edu. au Monash University, Dep. of Mathematics

Alexander MEN'SHCHIKOV saschaClgeorg.astro. uni-jena.de Max-Planck-Gesellschaft AG, Jena

Vito MENNELLA mennellaClastrna.na.astro. it Osservatorio Astronomico di Capodimonte

Dante MINNITI dminnitiCleso.org ESO, Garching

Joseph MONAGHAN joe.monaghanClsci.monash.edu.au Monash University, Dep. of Mathematics

Guy MONNET gmonnetCIeso. org ESO, Garching

Frederique MOTTE motteClgag. observ-gr. fr Observatoire de Grenoble

David MOUILLET mouilletClgag. observ-gr. fr Observatoire de Grenoble

Telemachos MOUSCHOVIAS tchmClastro. uiuc. edu University of Illinois, Dept. of Astronomy, Urbana

Takenori NAKANO nakanoClnro.nao.ac.jp Nobeyama Radio Observatory, National Astronomical Observatory

Thorsten NECKEL neckelClmpia-hd. mpg. de MPI fur Astronomie, Heidelberg

Dieter NURNBERGER nurnbergClastro. uni -wuerzburg. de Universitat Wurzburg, Astronomisches Institut

Rene OUDMAIJER roudClic. ac. uk Imperial College of Science, Blackett Laboratory, London

Gernot PAATZ gpaatzClhp2 .lsw . uni -heidelberg. de Landessternwarte Heidelberg

Maria Elisabetta PALUMBO mepalumboClastrct. ct. astro. it Universita di Catania, Istituto di Astronomia

Eric PANTIN pantinClsapvxg. saclay. cea. fr CEA - Centre d'Etudes de Saclay, Service d'Astrophysique

Beate PATZER patzerClphysik. TU-Berlin.de TU Berlin, Institut fur Astronomie und Astrophysik

Stefano PEZZUTO pezzutoClle. infn . it University of Leece, Dept. of Physics

Jonathan RAWLINGS jcrClstar.ucl.ac.uk University College London, Dept. of Physics & Astronomy

Andrea RICHICHI riehiehi~areetri. astro. it Osservatorio Astrofisico di Arcetri

Isabelle RISTORCELLI C.E.S.R., Toulouse

Michael ROSA ST-ECF, Garching

ristoree~eesr.enes.fr

mrosa~eso.org

Ralf SABLOTNY sablotny~fred. astro. uni - j ena. de Max-Planck-Gesellschaft AG, Jena

Paolo SARACENO saraeeno~sunir2. ifs i . fra. enr . it IFSI - CNR, Frascati

Wolfgang SCHMITT sehmitUgeorg.astro.uni-jena.de Max-Planck-Gesellschaft AG, Jena

XXI

Willem SCHUTTE sehutte~strwehem. strw. LeidenUni v. nl Leiden University Observatory

Russell SHIPMAN shipmanGplh. af . mil Phillips Laboratory, Geophysics Directorate

Ralf SIEBENMORGEN rsiebenm~iso. vilspa. esa. es ESA-Villafranca del Castillo Satellite Tracking Station

Gregory SLOAN sloan~ssa1. arc. nasa. gOY NASA Ames Research Center

Craig SMITH e-smi th~adfa. oz. au University College, ADFA, Dept. of Physics, Canberra

Marco SPAANS spaans~strw .leidenuni v . nl Leiden University Observatory

Thomas STANKE stanke~astro. uni -wuerzburg. de Universitat Wiirzburg, Astronomisches Institut

Jakob STAUDE staude~pia-hd.mpg.de MPI fiir Astronomie, Heidelberg

J iirgen STEIN ACKER stein~georg. astro. uni - j ena. de Max-Planck-Gesellschaft AG, Jena

Francesco STRAFELLA strafellaUe.infn.it University of Leece, Dept. of Physics

Ryszard SZCZERBA szezerba~iras. uealgary . ea The University of Calgary, Dept. of Physics & Astronomy

Mauricio TAPIA tapia~bufadora. astrosen. unam.mx U.N.A.M., Instituto de Astronomia

Stephen TAYLOR sdUstar. uel. ae. uk University College London, Dept. of Physics & Astronomy

Teresa TEIXEIRA T. C . Teixeira~qmw . ae . uk

XXII

Queen Mary and Westfield College, London

Alexander TIELENS tielensGdusty. arc .nasa.gov NASA Ames Research Center

Elisabetta TOMMASI IFSI - CNR, Frascati

Viktor TOTH Eotvos University, Budapest

elisaGsunir2.ifsi.fra.enr.it

IvtothGinnin.elte.hu

Mario van den ANCKER marioGastro. uva.nl Astronomical Institute, Amsterdam

Nikolai VOSHCHINNIKOV nvvGaispbu. spb. su St. Petersburg University, Astronomical Institute

Christoffel WAELKENS ehristoffelGster .kuleuven. ae. be Katholieke Universiteit Leuven, Instituut voor Sterrenkunde

Helen WALKER h. walkerGrl. ac . uk CCLRC - Rutherford Appleton Laboratory

Derek WARD-THOMPSON dwtGroe. ae . uk Royal Observatory Edinburgh

Mark WARDLE markGholly. pas. rochester. edu University of Rochester, Dept. of Physics and Astronomy

Walter WEGNER walterGastrLunLtorun.pl Pedagogical University, Dept. of Mathematics

Helmut WIESEMEYER p713hwiGmpifr-bonn.mpg.de MPI fur Radioastronomie, Bonn

Bogdan WSZOLEK bogdanGoa.uj .edu.pl J agiellonian University, Astronomical Observatory, Cracow, Poland

Gunther WUCHTERL wuchterlGamok. ast . uni vie. ae. at Universitiit Wien, Institut fur Astronomie

Harold YORKE yorkeGastro. uni-wuerzburg. de Universitiit Wurzburg, Astronomisches Institut

Annie ZAVAGNO annieGorion.ifsi.fra.cnr.it IFSI - CNR, Frascati

Hans ZINNECKER hzinneekerGaip. de Astrophysikalisches Institut Potsdam

Victor ZUBKO maouasGgluk. ape. org zubkoGastri.uni.torun.pl

Main Astronomical Obs., NAS, Kiev

Robert ZYLKA rzylkaGmpifr-bonn.mpg.de MPI fur Radioastronomie, Bonn