I \ , ~ ~ ~~~~~~.,: : t~~~~~. :.L c N', > I" -. f X-683-71:375 ' .! ~ , -- .. " T.~ ',A.," Ax . _ N ; - - - .j.~- , - ~. I ."-3-, .. :... '/- - N,V. #4 N I il 'HEGMNNNEBULA- AND- REIATED PROBLEMS: I : r) N' N / .x .2- 'N / I, IjI /" NC03 'N. A 4-N ;72-11750 (NASA-TNI-X-65749) THE GUIi~ NEBULA AND thru RELATED PROBLEI"IS S.P. iaran, et al (NASA):" Sep. 1971 234 p 4 !/: 03A NN ·' ' , N72-11774 _CSCL 03A Sep. 1971 234 p ',-1 NY ' j- Unclas -- 09173 G3/30 ''4 4. - NN' 'N 7~~~~ *NN' N' : ' N 4 i,~~~~~~,N 'N .......' I~ ~/ ,. .7~.. -. · ~'/' ....'-' ' ~/~ ~ ~ ' . ~' . ~.} ./ ~1~ '~ ' ,,..'~_'A'"· ~,~- - ',. j., '' i~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ,N '/ N ',/' ~ -' 7, -'~ -.' :~... N...'""- - 4. , N·: 'N -' -->..-:?,N ~ NATINAL TECHN 'ICA' 'K. ""'"-N1'":',,' ? N% :~~~~~, :"' ~~~~~~~~~~~~~~~~~~~~~~~~~~--NN: ~ ~ ~ ·-. ' ,m - NGT)R SPAC FLI ' . [~~~~~~~~~~~~~~~~~~~~~~~~~~r -.>~:''- 4 .1 ··.~~~~~~/ 'N ' r,:~~~~ACSNLMVIR (TRU N : N f~~~t N N~~ It N N N' N N~~~~ -N ''NI-N N 'N ' 2 J~~~~~~LNJcj · ` r :7· -: N -N 1N-N N 'N4 , , , I:~NASFCRORMATIXON Roprcduce"'N b' SDNMERVICAEG OY /1- -, N'' 4 '1C4 MNNO TO - -4 N N Ni N'N N~ ~ piged N'. N215 'N 44 .' )· CONTENTS Page PREFACE .......................................... vii INTRODUCTION ...................................... ix FRONTISPIECE.......... .............. ............ x COLIN GUM AND THE DISCOVERY OF THE NEBULA F. J. Kerr ............ .......... ................ 1 IDENTIFICATION OF THE GUM NEBULA AS THE FOSSIL STROMGREN SPHERE OF THE VELA X SUPERNOVA John C. Brandt ................................... 5 DISCUSSION ......................................... 10 THE SIZE AND SHAPE OF GUM'S NEBULA Hugh M. Johnson ................... 12 DISCUSSION ........................................ 21 FORMATION OF GIANT H II REGIONS FOLLOWING SUPERNOVA EXPLOSIONS L. Sartori .......................................22 DISCUSSION ......................................... 32 RADIO ASTRONOMY EXPLORER-1 OBSERVATIONS OF THE GUM NEBULA J. K. Alexander ................................... 34 A DISCUSSION OF THE GROUND-BASED RADIO OBSERVATIONS F. J. Kerr ...................................... 42 DISCUSSION ..................... .. ...... 45 RUNAWAY STARS IN THE GUM NEBULA J. Richard Gott, III and Jeremiah P. Ostriker .......... ..... 47 DISCUSSION ......................................... 58 1BLANK NOT fP"'ii£_; pR~,L7O"I-.,G U!1 PiE CONTENTS- (continued) Page STRUCTURE AND EVOLUTION OF FOSSIL H II REGIONS Richard McCray and Joseph Schwarz .................... 60 ' DISCUSSION ......................................... 72 , / THE VELOCITY AND COMPOSITION OF SUPERNOVA EJECTA Stirling A. Colgate ................................. 73 DISCUSSION . ....................................... 79 COSMIC RAYS FROM SUPERNOVAE AND COMMENTS ON THE/ VELA X PRE-SUPERNOVA A. G. W. Cameron .............. 80 DISCUSSION ......................................... 94 COSMIC-RAY EFFECTS IN THE GUM NEBULA R. Ramaty and E. A. Boldt ............................ 97 DISCUSSION . ........................................ 109 THE EARLY EVOLUTION OF GIANT H II REGIONS FORMED BY SUPERNOVA EXPLOSIONS Minas C. Kafatos .............. ...... /110 DISCUSSION .. ....................................... 127 THREE PROPOSED B-ASSOCIATIONS IN THE VICINITY OF ZETA PUPPIS Edward K. L. Upton ............................... 128 COMMENTS ON AN ASSOCIATION IN VELA W. C. Straka ................................. 136 A DISCUSSION OF THE H-ALPHA FILAMENTARY NEBULAE / AND GALACTIC STRUCTURE IN THE CYGNUS REGION Thomas A. Matthews and S. Christian Simonson, III ........... 138/ RADIOFREQUENCY RECOMBINATION LINES FROM THE INTERSTELLAR MEDIUM A. K. Dupree ...... .... ........................... 149 iv CONTENTS- (continued) Page THE APPEARANCE OF THE GUM NEBULA Bart J. Bok ...................................... 158 THE DIFFICULTY OF ULTRAVIOLET EMISSION FROM SUPERNOVAE Stirling A. Colgate ................................ 163 A NOTE ON THE POSSIBLE IMPORTANCE OF THE GUM NEBULA D. P. Cox ....... ................................ 166 X-RAYS FROM THE VELA-PUPPIS COMPLEX A. N. Bunner..................................... 169 THE BASIC ASSUMPTION Theodore P. Stecher ........ ........................ 180 LOW INTENSITY H-BETA EMISSION FROM THE INTERSTELLAR MEDIUM R. J. Reynolds, F. Roesler, F. Scherb, and E. Boldt ........... 182 LARGE NEBULAR COMPLEXES IN THE NORTHERN PORTION OF THE GALAXY William J. Webster, Jr . ........................... 210 PRELIMINARY RESULTS ON AN H-ALPHA MAP OF THE GUM NEBULA OBTAINED WITH THE D-2-A SATELLITE J. E. Blamont and A. C. Levasseur .. ................ 220 v PREFACE This preliminary edition of the proceedings of a symposiumheld at the God- dard Space Flight Center was prepared for circulation to workers actively en- gaged in this field, because of the considerable interest in observing the nebula during the approaching austral summer. As the distribution is necessarily limited, we hope that each recipient will make his copy available to any inter- ested colleagues whom we have overlooked. Time limitations at the symposium prevented the presentation of most of the results summarized in the papers that appear on pages 138 and 180. In addition, the last three papers in this volume are invited contributions that were not given at the symposium. The discussion sections have been summarized from the tapes of the symposium. The illustration on page 57 was prepared from the video recording of a blackboard sketch by Mr. Gott. The illustrations for Pro- fessor Bok's paper were chosen by the editors from the selection of photographs that he has generously made available to astronomers working on Vela X and the Gum Nebula; we have made some revisions in the overlays for these illus- trations. We are also responsible for the final presentation of the figures that illustrate the paper by Professor Blamont and Dr. Levasseur, and for some slight rework of the diagrams on pages 3 and 4. The tight schedule for the production of these preliminary proceedings has precluded us from sending the edited manuscripts and the proofs to the authors. Therefore we accept responsibility for any mistakes that have occurred in the process of publication. Mr. Howard Caulk has supervised editorial work on the illustrations for this volume. We thank Mr. Milton Kalet and Mrs. Mozelle Bird for their help in organizing the symposium, and Mrs. Margaret A. Becker for taking charge of the production. Stephen P. Maran John C. Brandt August 27, 1971 Theodore P. Stecher T PAGE P.-AiP ltC FILMED vii INTRODUCTION Stephen P. Maran Laboratory for Solar Physics Goddard Space Flight Center Greenbelt, Maryland 20771 Taken separately, the Gum Nebula, the Vela X remnant, the hot stars gamma Velorum and zeta Puppis, the B-associations in Vela-Puppis and the pulsar PSR 0833-45 are each a fascinating subject for astrophysical investigation. Viewed collectively, with the remnant Puppis A and several slow pulsars ap- parently in the background, this appears to be one of the most interesting re- gions of the sky. Leafing through these proceedings, one is perhaps most impressed by the way in which each of many disciplines has played a significant role. It is clear that both our present understanding and future progress depend on ground-based optical and radio astronomy, rocket and satellite observations in the radio, visible, ultraviolet, and x-ray regimes, and on the solution of a great many theoretical problems in the physical state of the interstellar medium, in stellar evolutionary processes and perhaps also in the dynamics of runaway stars. The reader may wish to consult the reports on the symposium that appear in the August, 1971 issue of Sky and Telescope and in the September, 1971 Physics Today. Since this conference was held, George Wallerstein and Joseph Silk have measured the expansion rate of Vela X, as revealed by high velocity absorption lines in the spectra of two distant stars. This is undoubtedly only the first of many new discoveries as astronomers continue to unravel the problems of the Gum Nebula and its associated phenomena. ix CONFERENCE ON THE GUM NEBULA AND RELATED PROBLEMS c...:>- :::l o a a::: ~ w a::: f­ a z • 40 Degrees ---......... MAY 18. 1971 x X-683-71-375 THE GUM NEBULA AND RELATED PROBLEMS edited by Stephen P. Maran John C. Brandt and Theodore P. Stecher Goddard Space Flight Center Greenbelt, Maryland 20771 Proceedings of a Conference at the Goddard Space Flight Center on May 18, 1971 (Preliminary Edition) Goddard Space Flight Center Greenbelt, Maryland COLIN GUM AND THE DISCOVERY OF THE GUM NEBULA F. J. Kerr Astronomy Program, University of Maryland College Park, Maryland 20742 As some later speakers will be talking of a proposed time scale of tens of thousands of years, it is appropriate to begin this symposium with a brief sketch of some recent history. Most people in this room do not know who Colin Gum was. As a former colleague and personal friend of his, I want to give a short outline of his career and scientific work. He made three principal contributions to astronomy, and it is interesting that all three of these are relevant to today's symposium. Colin Gum lived from 1924 to 1960. He graduated with a Bachelor of Science Honours degree in physics at the University of Adelaide in South Australia, and later received his Ph.D. at the Australian National University for work done at the Mount Stromlo Observatory. He then spent three years in my group at the CSIRO Radiophysics Laboratory in Sydney, followed by a year in Pasadena as a Carnegie Fellow. In fact,