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IM w sity Microfilms International V lalj* 1.0 Itt _ to. y£ 22 £ b£ 2.0 1.1 UL 11.25 111 1.4 1.6 MICROCOPY RESOLUTION TEST CHART NATIONAL BUREAU OF STANDARDS STANDARD REFERENCE MATERIAL 1010a (ANSI and ISO TEST CHART No. 2) University Microfilms Inc. 300 N. Zeeb Road, Ann Arbor, MI 48106 INFORMATION TO USERS This reproduction was made from a copy of a manuscript sent to us for publication and microfilming. While the most advanced technology has been used to pho­ tograph and reproduce this manuscript, the quality of the reproduction is heavily dependent upon the quality of the material submitted. Pages in any manuscript may have indistinct print. In all cases the best available copy has been filmed. The following explanation of techniques is provided to help clarify notations which may appear on this reproduction. 1. Manuscripts may not always be complete. When it is not possible to obtain missing pages, a note appears to indicate this. 2. When copyrighted materials are removed from the manuscript, a note ap­ pears to indicate this. 3. Oversize materials (maps, drawings, and charts) are photographed by sec­ tioning the original, beginning at the upper left hand comer and continu­ ing from left to right in equal sections with small overlaps. Each oversize page is also filmed as one exposure and is available, for an additional charge, as a standard 35mm slide or in black and white paper format.4 4. Most photographs reproduce acceptably on positive microfilm or micro­ fiche but lack clarify on xerographic copies made from the microfilm. For an additional charge, all photographs are available in black and white standard 35mm slide format.* ♦For more information about black and white slides or enlarged paper reproductions, please contact the Dissertations Customer Services Department. T T.1V /T J Dissertation vJ 1VJL1Information Service University Microfilms International A Bell & Howell Information Company 300 N. Zeeb Road, Ann Arbor, Michigan 48106 8618861 Wahlgren, Glenn Michael A SPECTRAL ANALYSIS OF RV TAURI VARIABLES The Ohio State University Ph.D. 1986 University Microfilms International 300 N. Zeeb Road, Ann Arbor, Ml 48106 Copyright 1986 by Wahlgren, Glenn Michael All Rights Reserved A SPECTRAL ANALYSIS OF RV TAURI VARIABLES DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Glenn Michael Wahlgren, B.S.,M.A. ***** The Ohio State University 1986 Dissertation Committee: Approved by Ronald Kaitchuck,Ph.D. Arne Slettebak,Ph.D. Robert F. Wing,Ph.D. Robert F. Wing, Adviser Department of As^onomy Copyright by Glenn Michael Wahlgren 1986 DEDICATION To Sharon and Michael ACKNOWLEDGEMENTS It is a pleasure to thank my adviser, Professor Robert F. Wing, from whom I have learned much about being an astrono­ mer, for suggesting this topic and offering his insights. Special thanks go to Brian Skiff and Dr. Nat White, of Lowell Observatory, for making photometric observations, and Professors R. Kaitchuck and R.F. Wing for obtaining IDS spectra which were used in this dissertation. The staffs of both Lowell Observatory and Perkins Observatory have also been a great help, especially Peter Stoycheff, for the drafting of several figures presented in this dissertation. The synthetic spectrum analysis was made possible by the generosity of Dr. C. Sneden, of the University of Texas, in allowing me to use his program, MOOG, as well as that of Dr. R.E. Luck, of Case Western Reserve University, who kindly supplied the model stellar atmospheres. Finally, I would like to thank my wife, Sharon, for being so understanding and providing incentive to finish. VITA May 15, 1956... Born - Jersey City, New Jersey 1978 . B.S., Pennsylvania State University, University Park, PA. 1978 - 1981.... Scientist/Engineer, McDonnell Douglas Astronautics, Huntington Beach, CA. 1981 . M.A., California State University, Long Beach, CA. 1981 - 1984.... Teaching Associate (various times) Department of Astronomy, The Ohio State University, Columbus, Ohio 1982 - 1984.... Research Assistant (various times) Department of Astronomy, The Ohio State University, Columbus, Ohio 1984 - 1985.... Perkins Observatory Research Assistant, Department of Astronomy, The Ohio State University, Columbus, Ohio 1984 - 1985.... Consultant, Ohio Board of Regents, Columbus, Ohio \ 1985 - 1986.... Graduate School Presidential Fellow, Department of Astronomy, The Ohio State University, Columbus, Ohio PUBLICATIONS "Remarkable Modification of Lightcurves for Shadowing Effects on Irregular Surfaces: The Case of 37 Fides", V. Zappala, DiMartino, F. Scaltriti, R. Burchi, L. Milano, G. Wahlgren, and K. Pavlovski, Astron. Astrophys. 123, 362, (1983). Atlas of Hiqh-Resolution IUE Spectra of Late-Type Stars, R.F. Wing, K.G. Carpenter, and G.M. Wahlgren, Perkins Observatory Special Publication No.l, (1983). ABSTRACTS "An Atlas of High-Resolution IUE Spectra of Late-Type Stars", R.F. Wing, K.G. Carpenter, and G.M. Wahlgren, BULL.A.A.S. JL4, 918, (1982). "The Recent Deep Minimum of VX Sagittarii", R.F. Wing and G.M. Wahlgren, BULL.A.A.S. ^6, 897, (1984). "Observations of TiO Absorption and Balmer-Line Emission in RV Tauri Variable Stars", G.M. Wahlgren, R.F. Wing, and N. White, BULL.A.A.S. 16, 897, (1984). "The Peculiar Spectrum of HQ Mon", G.M. Wahlgren, R.F. Wing, R.H. Kaitchuck, S.R. Baird, D.J. MacConnell, and D.W, Dawson, BULL.A.A.S. 17, 599, (1985). "Photometric and Spectroscopic Observations of R Set during a Strong-TiO Minimum and Subsequent Recovery", R.F. Wing, G.M. Wahlgren, G. Fontaine, and F. Wesemael, B U L L ^ A ^ J7, 875, (1985). "Atmospheric Parameters of RV Tauri Variables", G.M. Wahlgren, BULL.A.A.S. 17. 875, (1985). - v - TABLE OF CONTENTS Page DEDICATION ................................................. ii ACKNOWLEDGEMENTS ..........................................i i i VITA ...........................................................iv LIST OF FIGURES ........................................... viii LIST OF TA B L E S .............................................. xii CHAPTER I. INTRODUCTION ........................................ 1 II. OBSERVATIONAL MATERIAL .......................... 21 Introduction ................................... 21 Spectroscopic Observations ................... 22 Instrumentation ............................ 22 The Observations ............................ 23 Data Reduction ...............................27 Photometric Observations ..................... 30 The Photometric S y s t e m ..................,. 30 Instrumentation and Observing P r o c e d u r e s ............................ 32 Photometric Reductions ................... 34 III. OBSERVATIONAL PROPERTIES ........................ 40 Spectral Classification ..................... 40 - vi - Spectroscopic .............................. 40 Photometric................................... 47 Suspect Classifications .................. 56 Color Excesses ................................... 59 Metallicity ..................................... 62 IV. SYNTHETIC SPECTRUM ANALYSIS ................... 76 Introduction ................................... 76 The Synthetic Spectrum Program .............. 78 The Input D a t a ................................... 89 Model Atmospheres ....................... • . 90 Atomic Line D a t a ............................ 91 Number Density ............................ 94 Program Initialization .............. 102 Observational Considerations ............ 102 Spectrum Rectification ................... 103 Computational Resolution ................ 106 A n a l y s i s .................................... 108 Application to RV Tauri Variables ......... 116 V. THE NATURE OF RV TAURI VARIABLES ............... 133 Introduction ................................... 133 Metallicity .................................... 134 Absolute Magnitudes ......................... 138 Galactic Distribution and Population T y p e s .................................... 146 Evolutionary Status ......................... 150 APPENDICES A. Spectra of the RV Tauri V a r i a b l e s ............... 153 BIBLIOGRAPHY 220 LIST OF FIGURES FIGURE PAGE 1. Spectral features within photometric bandpasses............................................ 49 2. Eight-color bandpasses and warm stellar spectrum............................................... 50 3. Eight-color bandpasses and cool stellar spectrum............................................... 51 4. Eight-color photometry spectral classification.............. 53 5. Photometry of R Set...................................55 6. R^ versus Spectral Type diagram.....................65 7. Rm versus Spectral Type diagram.....................66 8. Eight-color photometry luminosity discrimination........................................ 72 9. The 6cn - [Fe/H] diagram.............................73 10. Synthetic spectra for BD+1°2916................... .110 11. Synthetic spectra parameterization................ 115 12. The observed spectrum and derived continuum of TT Oph.............................................122 13. TX Oph s observed and synthetic spectra. 123 14. V564 Oph : observed and synthetic spectra. 124 15. The Mv - Period diagram............................. 144 16. The spectrum of DY Aql on 23 May 1984........... 154 17. The spectrum of DY Aql on 24 May 1984........... 155 - viii - 18. The spectrum of DY Aql on 9 .Jun 1984. 19. The spectrum of DY Aql on 10 Jun 1984. 20. The spectrum of DY Aql on 23 Jun 1985. 158 21. The spectrum of DS Aqr on 26 Jun 1985. 22. The spectrum
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