DOCSLIB.ORG

Mass Transfer in Stellar X-Ray Sources

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mass Transfer in Stellar X-Ray Sources INIS-mf—8631 FRANK VERBUNT ERRATA p.3O: 1.36: p(:)R25 should be p(:)R"2'5 p.55: add: Space Science Reviews, 1982, in press. p.57: 1.8: lOkeV should be 1 keV p.64: eq.(9) left hand side should be ph p.66: table 2: p should be in units g/cm3 p.68: 1.17: gas pressure is dominant at radii r > 1000 km, p. 73: the cooling formula of Bisnovatyi-Kogan and Blinnikov has a term VAT this should be AVT. p.76: 1.13: M should be M. p.95: unnumbered formula: 2(a-x ) should be 2(a-2x) Men moet gelijkelijk laohen en wetenschap beoefenen. Epikouros il MASS TRANSFER IN STELLAR X-RAY SOURCES PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE WISKUNDE EN NATUURWETENSCHAPPEN AAN DE RIJKSUNIVERSITEIT TE UTRECHT, OP GEZAG VAN DE RECTOR MAGNIFICUS PROP.DR. M.A. BOUMAN, VOLGENS BESLUIT VAN HET COLLEGE VAN DECANEN IN HET OPENBAAR TE VERDEDIGEN OP WOENSDAG 7 JULI 1982 DES NAMIDDAGS TE 2.45 UUR DOOR FRANCISCUS WILHELMUS MARIA VERBUNT GEBOREN OP 14 MEI 1953 TE GOIRLE I PROMOTOREN : PROF. DR. H.G. VAN BUEREN PROF. DR. E.P.J. VAN DEN HEUVEL (UNIVERSITEIT VAN AMSTERDAM) Dankbetuiging Het Is een plezierige plicht al die personen te bedanken zonder wie dit proefschrift niet tot stand zou zijn gekomen. In de eerste plaats zijn dat uiteraard mijn beide promotores: Henk van Bueren en Ed van den Heuvel. Zowel binnen als buiten de sterrenkunde was het me een genoegen met hen te mogen omgaan. Ze lieten me veel vrijheid, maar waren steeds aanwezig als ik hun hulp nodig had: ik ben hen hier zeer erkentelijk voor. Roeif Takens wil ik bedanken voor de tijd en de moeite die hij heeft genomen om me op weg te helpen in het onderzoek naar groei8chijven. In het tweede deel van dit proefschrift heeft menige opmerking van hem een plaats gevonden. Op het moment dat het onderzoek naar groeischijven in een luwte raakte, bracht Jan van Paradijs uit de V.S. de vaart en de allure mee waar het eerste deel van dit proefschrift een gevolg van is. Mijn dank! Karin Kieboom wil ik bedanken voor het doorzettingsvermogen waarmee zij de literatuur over massaoverdracht in dubbelsterren met een lage massa heeft bestudeerd. Het derde deel van dit proefschrift profiteert daarvan. Naast deze mensen en de overige co-auteurs wil ik ook nog al diegenen bedanken met wie ik op zo'n plezierige manier over allerlei fysische problemen heb kunnen discussieren: met name noem ik Bram Achterberg, Aad van Ballegooijen, John Heise, en Leo van der Horn. Ed Faverey, Maria Hoesman, en Evert Landré dank ik voor de nauwgezetheid waarmee ze de figuren uit dit proefschrift hebben verzorgd. De Nederlandse Organisatie voor Zuiver Wetenschappelijk Onderzoek, Z.W.O., heeft gedurende de eerste drie jaar van dit onderzoek in mijn levensonderhoud voorzien, de Rijksuniversiteit van Utrecht in het laatste jaar. Dat ik me al die tijd redelijk wel ben blijven voelen dank ik niet in de laatste plaats aan de goede vriendschap met Frits Paerels en met Astrid de Leeuw. Summary ' In this thesis some aspects of binaries that emit X-rays, are discussed. The brightest X-ray sources in our galaxy as observed by satellites like UHURU all consist of a compact star - i.e. a star with a similar mass as the sun, but with a much smaller radius - and an accompanying ordinary star. The ordinary star loses matter that falls in the deep gravitational potential well of the compact star, and emits its released energy as X-rays. In chapters VII and VIII we investigate which mechanism is responsible for the mass transfer in systems where the mass-losing star is less massive than the sun. According to the theory of general relativity the binary loses energy in the form of gravitational radiation, which causes the stars to fall towards one another. According to the current theory, proposed by Paczynski in 1967, this effect sufficiently explains the mass transfer. In chapter VII it is shown that this is not the case, and that especially in the somewhat wider binaries much more matter is transferred than can be explained in terms of this theory, even when we take some hitherto neglected effects into account. In chapter VIII we describe another mechanism of mass transfer. It is well known that a star like the sun loses angular momentum with its stellar wind. When such a star loses angular momentum in a binary, this will lead to loss of angular momentum from the system, as rotation and revolution are tldally coupled in a narrow binary. By a rough estimate we show that it is possible to explain the observed mass-transfer rates with this mechanism. The transferred matter will often enter a gaseous disk around the compact star, and spiral inwards slowly through this disk. In chapter V we investigate the conditions for the formation of such a disk, and write down the equations governing its structure. A classification scheme enables us to discuss the different models that have been proposed» It is concluded that different models lead to very similar results for those regions of the disk where gas pressure is more important than radiative pressure, and that these results agree fairly well with observations. No consistent model has been constructed as yet for the region where radiative pressure is dominant, and that occurs only around non-magnetic neutron stars or black holes. Theoretically one predicts that the optical light emitted by a disk around a neutron star is mainly caused by X-ray photons from the immediate surroundings of the neutron star that hit the outer disk surface, are absorbed, theraalised, and re-eaitted in the optical and ultraviolet region* of the spectrum* Thia expectation it verified by comparison with the collected observational data of low-mass X-ray binaries. In chapter II-IV optical observations on two sources are analysed. 2A0311-227 consists of a strongly magnetised white dwarf and a low-mass companion. Matter is falling from the companion towards the surface of the white dwarf along the magnetic field lines. The lightcurves are very intricate, and difficult to explain in a detailed model.' But this much can be concluded that the striking change of the Ha-lines from emission into absorption is caused by the appearance of a bright red source of light behind the gae that emits the emission lines. In chapter IV an MgH and Mgb triplet depression are identified in the spectrum of the transient X-ray source Cen X-4. This depression must be explained by the presence of a K-star, and the existence of a companion to the neutron star is therefore proved observationally. Apart from this we find that the emission lines are still rather strong, although the X-ray flux has decreased with a factor 101*. A possible explanation for this is given as heating of the gas by thermal radiation from the hot neutron star. In the introduction I try to improve the legibility of the articles for a more general public than the specialists for who the articles were written by giving some information on the general background of this research. Also I use the opportunity to discuss the recent X-ray and infrared observations on 2AO311-227. CONTENTS Dankbetuiging 5 Summary 6 I Introduction 9 II Simultaneous Optical Photometric and Spectroscopie Observations of 2A0311-227 23 (co-authora: E.P.J. van den Heuvel, Th.J. van der Linden, J. Brand, F. van Leeuwen, and J. van Paradijs) III Simultaneous Spectroscopie and Photometric Observations of 2A0311-227 33 (co-authors: as chapter II) IV Spectroscopie Observations of the Optical Counterpart of Centaurus X-4 45 (co-authors: J. van Paradijs, Th.J. van der Linden, H. Pedersen, and W. Warnsteker) V Accretion Disks in Stellar X-ray Sources 55 VI Optical Properties of Low-mass X-ray Binaries 85 (co-author: J. van Paradijs) VII Some Aspects of Low-mass Close Binary Models for Bright Galactic Bulge X-ray Sources and 4U1626-67 91 (co-author: Karin H. Kieboom) VIII Magnetic Braking in X-ray Binaries 103 (co-author: C. Zwaan) Samenvatting 110 Levensloop 112 INTRODUCTION I 1. Historical overview and general background. When the launch of the UHURÜ satellite, December 12 1970, opened the era of systematic investigation of the X-ray sky, rocket experiments had already revealed the existence of a surprisingly large number of strong celestial X-ray sources. From the concentration of the sources towards the galactic plane it was clear that a substantial fraction of the objects in the second UHURU catalogue of X-ray sources (1) is situated in our own galaxy. A model for the X-ray sources in our own galaxy had already been proposed by Shklovsky (2), following the identification of one of them with a nova-like optical star (3). In this model a neutron star captures matter lost by an accompanying main-sequence star of low (<1 Me) mass. As the captured matter falls into the deep gravitational potential well of the neutron star, an enormous amount of energy is liberated and emitted as X-rays (4). Several serious objections to this model were raised almost immediately. The supernova explosion in which the neutron star is formed will tear a low-ma88 companion star to pieces (5). And even granted that the low-mass star survives the explosion, it would still be thrown out of the neighbourhood of the neutron star, as the explosion dissolves the binary (6). It was therefore a great surprise when the analysis of one year of data from the pulsating source Cen X-3 (i.e.
Load more

Recommended publications
  • Curriculum Vitae Ralph A.M.J. Wijers
    Curriculum Vitae Ralph A.M.J. Wijers August 2018 Biographical sketch Ralph Wijers has been professor of high-energy astrophysics at the Uni- versity of Amsterdam since 2002. He specialises in energetic explosions from extreme objects such as black holes and neutron stars and is PI of the AARTFAAC all-sky radio telescope. He got his MSc from Leiden Observatory and his PhD from the University of Amsterdam. He went on to Princeton on a NASA Compton Fellowship and Cambridge on a Royal Society Fellowship, after which he became assistant professor at Stony- brook University. He is a VICI and ERC Advanced Investigator laureate and winner of the 2002 EU Descartes Prize for his discoveries in gamma- ray bursts, with an international team. He teaches enthusiastically from the broad undergraduate level to highly specialised graduate courses, and is actively involved in outreach. Astrid and he have two daughters. He is a member of several national and international scientific governing and advisory councils. Since 2011, he is director of the Anton Pannekoek Institute for Astronomy. Address: Anton Pannekoek Institute for Astronomy Faculty of Science, University of Amsterdam Science Park 904, 1098 XH Amsterdam, The Netherlands. Tel: +31-20-5257488 (self) or 7491 (secr.) Fax: +31-20-5257484 Email: [email protected] Website: www.uva.nl/en/profile/w/i/r.a.m.j.wijers/r.a.m.j.wijers.html ORCID: orcid.org/0000-0002-3101-1808 2 CONTENTS Contents Curriculum Vitae — Major and Summary Facts 3 1 Summary information 3 2 Key papers 7 3 History of key ideas 8 4 Invited talks and colloquia 9 Curriculum Vitae — Complete Listings 11 5 PhD students and postdocs supervised 11 5.1 PhDstudents....................................
    [Show full text]
  • Livio Scarsi: 40 Years of Astrophysics from Space
    Livio Scarsi: 60 years of scientific activity dedicated to Physics, Cosmic Rays and High Energy Astrophysics from Space. (B. Sacco, 6th Intnl Workshop of the “Data Analysis in Astronomy, Livio Scarsi, 15-22 April 2007, Erice, Italy ) The reach scientific career of Livio Scarsi starts at Genoa University, as physics student in the Institute of Augusto Occhialini father of Beppo Occhialini. On 1950’ Livio took the degree in physics discussing a thesis on “ Cosmic Radiation Soft Electromagnetic Component at Pic du Midi : Investigation with nuclear emulsions “ . Tutor : Giuseppe (Beppo) Occhialini . “ During the studies in Genoa he had, also, the opportunity to know Bruno Rossi. Beppo Occhialini and Bruno Rossi are the reference points in the scientific life of Livio. From memories of Livio: Bruno Rossi and Beppo Occhialini Artistic photo composition by A. Spizzichino, “The Active X-ray Sky”, 21-24 October, 1997, Roma A. Watson, Intl. Workshop “ The UHE Universe”, Villa Mondragone, Frascati,19-21 June,2006 In 1952 Livio follows Beppo Occhialini in Milan and in 1955 Beppo send Livio in France, at the Centre d’Etudes Nucleaires de Saclay where he remains for 3 years: researches for “New Particles” in the Cosmic Radiation with the tecnique of Nuclear Emulsions flown in the Upper Atmosphere with Stratospheric Balloons. Relevant results are : First classification of Decay modes for K-mesons and Hyperons In 1957 he comes back in Milan but ….. From memories of Livio: “A. Watson, UHE Workshop , Villa Mondragone, Frascati, June 21, 2006.” Volcano Ranch , “ The desert Quinn” In Volcano Ranch, New Mexico desert, Jonh Linsley and Livio Scarsi installed 19 plastic scintillators (3.3 m2 area each-one) in an exagone of about 2,430,000 m2 area.
    [Show full text]
  • Optical Studies of Massive X-Ray Binaries" Door E.J
    C 7A OPTICAL STUDIES OF SIVE m EJ. ZUIDERWIJK optical studies of massive X- ray binaries ACADEMISCH PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE WISKUNDE EN NATUURWETENSCHAPPEN AAN DE UNIVERSITEIT VAN AMSTERDAM, OP GEZAG VAN DE RECTOR MAGNIFICUS, DR. J. BRUYN, HOOGLERAAR IN DE FACULTEIT DER LETTEREN, IN HET OPENBAAR TE VERDEDIGEN IN DE AULA DER UNIVERSITEIT (TIJDELIJK IN DE LUTHERSE KERK, INGANG SINGEL 411, HOEK SPUI) OP WOENSDAG 20 JUN11979 DES NAMIDDAGS TE 15.00 UUR PRECIES DOOR EDUARDUSJOSEPHUSZUIDERWIJK GEBOREN TE HAARLEM PROMOTOR : Prof. Dr. E.P.J. van den Heave 1 COREFERENT : Dr. H.G L.M. Lamers The work described in this thesis was supported by the "Netherlands Organi- sation for the advancement of Pure Re- search" (ZWO) and by the University of of Amsterdam. -\ Voor mijn Iet en onze Ouders i Na het voltooien van mijn proefschrift wil ik graag allen bedanken die aan het tot stand komen ervan hebben bijgedragen. Allereerst dank ik mijn ouders, die mij de gelegenheid gaven een aca- demische opleiding te volgen. Bijzonder erkentelijk ben ik mijn Promotor Prof. Dr. E.P.J. van den Heuvel, die het voor mij mogelijk maakte het onderzoek uit te voeren. Hij is daarbij altijd een steun geweest door de interesse getoond in mijn werk, die onder andere tot uiting kwam in langdurige en diepgaande gedach- tenwisselingen. De coreferent Dr. H.J.G.L.M. Lamers dank ik voor het kritisch lezen van het proefschrift. Het grootste deel van de in mijn proefschrift verwerkte publicaties zijn tot stand gekomen in nauwe samenwerking met mijn collega's van het Sterrenkundig Instituut van de universiteit van Amsterdam en van het As- trophysisch Instituut van de Vrije Universiteit van Brussel.
    [Show full text]
  • Uva-DARE (Digital Academic Repository)
    UvA-DARE (Digital Academic Repository) A comparison between the rapid burster and GRO J1744-28 Lewin, W.H.G.; Rutledge, R.E.; Kommers, J.M.; van Paradijs, J.A.; Kouveliotou, C. DOI 10.1086/310022 Publication date 1996 Published in Astrophysical Journal Link to publication Citation for published version (APA): Lewin, W. H. G., Rutledge, R. E., Kommers, J. M., van Paradijs, J. A., & Kouveliotou, C. (1996). A comparison between the rapid burster and GRO J1744-28. Astrophysical Journal, 462, L39-L42. https://doi.org/10.1086/310022 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:30 Sep 2021 THE ASTROPHYSICAL JOURNAL, 462 : L39–L42, 1996 May 1 q 1996. The American Astronomical Society. All rights reserved.
    [Show full text]
  • Faint Gamma-Ray Bursts and Other High-Energy Transients Detected
    Faint Gamma-Ray Bursts and Other High-Energy Transients Detected with BATSE by Jefferson Michael Kommers Submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics at the MASSACHUSETTS INSTITUTE OF TECHNOLOGY February 1999 © Massachusetts Institute of Technology 1999. All rights reserved. C Author........V .V ....... .. .. ...........- ... -- - ..... ...........----.- - Department of Physics December 15, 1998 d4 Certified byV Walter H. G. Lewin Professor of Physics Thesis Supervisor Accepted by ............... /Thomas, .Greytak Professor of Physics Associate Department Head for Education MCH SETTS INSTI TUTE LIBRARIES Faint Gamma-Ray Bursts and Other High-Energy Transients Detected with BATSE by Jefferson Michael Kommers Submitted to the Department of Physics on December 15, 1998, in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Physics ABSTRACT The Burst and Transient Source Experiment (BATSE) onboard the Compton Gamma Ray Observatory detects gamma-ray bursts (GRBs) and other high-energy astronomi- cal transients using a real-time burst detection system running onboard the spacecraft. This thesis describes a search of the archival BATSE data for GRBs, emission from soft gamma-ray repeaters (SGRs), bursts and flares from X-ray binaries, and other transients that were not detected by the onboard system. The search covers six years of the mission, from 1992 December 9.0 to 1997 December 17.0. The search reveals 873 GRB candidates that did not activate the onboard burst detection because they were too faint, because they occurred while the onboard system was disabled for technical reasons, or because their time profile artificially raised the onboard detection threshold.
    [Show full text]
  • Compact Stellar X-Ray Sources Edited by Walter Lewin & Michiel Van Der Klis Frontmatter More Information
    Cambridge University Press 978-0-521-82659-4 - Compact Stellar X-ray Sources Edited by Walter Lewin & Michiel van der Klis Frontmatter More information COMPACT STELLAR X-RAY SOURCES X-ray astronomy provides the main window onto astrophysical compact objects such as black holes, neutron stars and white dwarfs. In the past ten years new observational opportunities have led to an explosion of knowledge in this field. In sixteen chapters, written by leading experts, this book provides a comprehensive overview of the obser- vations and astrophysics of X-ray emitting stellar-mass compact objects. Topics discussed in depth include the various phenomena exhibited by compact objects in binary systems such as X-ray bursts, relativistic jets and quasi-periodic oscillations, as well as gamma-ray burst sources, super-soft and ultra-luminous sources, isolated neutron stars, magnetars and the enigmatic fast transients. The populations of X-ray sources in globular clusters and in external galaxies are discussed in detail. This is an invaluable reference for both graduate students and active researchers. Walter Lewin is Professor of Physics at MIT. A native of The Netherlands, Professor Lewin received his Ph.D. in Physics from the University of Delft (1965). In 1966, he went to MIT as a postdoctoral associate in the Department of Physics and was invited to join the faculty as Assistant Professor later that same year. He was promoted to Associate Professor of Physics in 1968 and to full Professor in 1974. Professor Lewin’s honors and awards include the NASA Award for Exceptional Scientific Achievement (1978), twice recipient of the Alexander von Humboldt Award (1984 and 1991), a Guggen- heim Fellowship (1984), MIT’s Science Council Prize for Excellence in Undergraduate Teaching (1984), the W.
    [Show full text]
  • Johannes A. Van Paradijs (1946–99) Sources, and Found Them All to Be About 16 Km, Typical of a Neutron Star
    news and views Obituary ‘standard candle’. From this he was able to measure the diameters of several burst Johannes A. van Paradijs (1946–99) sources, and found them all to be about 16 km, typical of a neutron star. Among his Jan van Paradijs, who died in Amsterdam other discoveries were the demonstration AM on 2 November, was one of the world’s that X-ray-burst sources are members of foremost astrophysicists. He will probably binary systems, and the first spatially be remembered most for the discovery, in resolved spectroscopic mapping of an . AMSTERD 1997, of the first optical afterglow of a accretion disk that forms between two UNIV g-ray burst, which established the stars in a low-mass binary. extragalactic nature of these bursts and In 1978, while working at the European solved what had for some 25 years been Southern Observatory in Chile, together one of the greatest problems of with Holger Pedersen from Copenhagen, astrophysics. Because of this first optical van Paradijs discovered the first optical sighting, which has since been followed by flash from an X-ray burst, by a dozen others, we now know that g-ray simultaneously combining telescope and bursts occur in very distant galaxies and satellite data. Such simultaneous represent the largest explosions of energy observations of unpredictable, brief events in the Universe since the Big Bang. require much organization and a flair for Born into a bricklayer’s family in logistics. There can be no doubt that van Haarlem, The Netherlands, van Paradijs Paradijs’ expertise in this area gave him a was the eldest of seven children.
    [Show full text]
  • Research Highlights 1995-1997
    NASNCR._.- _"7--- 207772, ,,....'_ ....__. Research Highlights 1995-1997 -, :.i_¸ !ii_i'i_i_ii!!/!i!i!:;-:II: Institute for Space Physics, Astrophysics & Education A Cooperative Agreement Between The University of Alabama in Huntsville • NASA/Marshall Space Flight Center • Universities Space Research Association 1995-1997 Highlights Table of Contents .........................................................................._;..{ Finding the smoking ,,,,un in gamma-ray. , bursts ....... p. 3 iiiiiiiiiiiiiiiiiiiiii_iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii_iiiiiiiiiiiiiiiiii!iiiiiiiiiiiiiii!i!i!i_iiiiiii_iiiiiiiiiiiii_i:iiiii!iii:iiiiiii_i!i_i_i_i_i_iii:i:i!i_iii:iiiii_iiiiiiiiiiiiiii_iiiii_iiiiiiiiiiiiiii!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i_i_i_i!i!i!i_i!iii!i!i!ii` ::iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii_iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii!!!!_` What is a gamma-ray burst? !i!i!i!i!i!iii!i!i!i!i!_ii!i!iii!i!iii!i!i!iii!iii!i!i!i!i!i!i!i!i!i!iii!i!i!i!i!i!i!i!i!i!i!i!i!__i_i_i Playing peekaboo with gamma-ray bursts ............... p. 4 Red-shift data show bursts travel FAR Spectral pulses muddle burst source study . p. 5 !!iiiiiiiiiiiiiiiiiiiiiiiiiiiiii iiiiiiiiiiiiiiiiiiiiiiiiiiiiiii Einstein was right: Black holes do spin .................... p. 6 This is a cosmic ray detector? ........i!ii!i!i!_!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!i!_i_#_ Astronomers find 'one-man X-ray band' ................
    [Show full text]
  • My Quarter Century with Jan Van Paradijs
    default arXiv:astro-ph/0105344v2 9 Apr 2004 For all who loved Jan My Quarter Century with Jan ASP Conference Series, Vol. 308, 2003 E.P.J. van den Heuvel, L. Kaper, E. Rol, R.A.M.J. Wijers My Quarter Century with Jan Walter Lewin Massachusetts Institute of Technology, USA A quarter century ago, Jan van Paradijs and I embarked on a scientific journey, our lives became entwined, and a friendship evolved that shaped both our lives scientifically and in personal matters. To tell our story was very difficult for me. I went through 24 years of notes in my calendars and re-lived more than 8000 days of my own and Jan’s life, 20 years of slides, 15 years of e-mail. There were times that I had to stop and leave it alone for a week or more as it became too emotional. Few people know (perhaps only two) what we meant for each other. When Jan died, part of me died. 1. The Early (X-ray Burst) Years We first met on April 5, 1976 at ESTEC in Noordwijk, the Netherlands where I gave a colloquium on X-ray bursts. X-ray bursts were a very hot topic at the time. This was less than half a year after their discovery by Josh Grindlay and John Heise with ANS, and only one month after the discovery of the Rapid Burster with SAS-3. The next year Jan applied for a SAS-3 position at MIT. George Clark (PI on SAS-3) asked me to meet with Jan in Amsterdam “to look him over.” After my colloquium at the University of Amsterdam on February 18, 1977, I had dinner with Jan and some students, among them Jan’s graduate student Ed Zuiderwijk.
    [Show full text]