THIRTEEN-COLOR PHOTOMETRY OF SUBDWARFS Item Type text; Dissertation-Reproduction (electronic) Authors Schuster, William John, 1948- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 05/10/2021 11:13:47 Link to Item http://hdl.handle.net/10150/289363 INFORMATION TO USERS This material was produced from a microfilm copy of the original document. While the most advanced technological means to photograph and reproduce this document have been used, the quality is heavily dependent upon the quality of the original submitted. The following explanation of techniques is provided to help you understand markings or patterns which may appear on this reproduction. 1. 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If necessary, sectioning is continued again — beginning below the first row and continuing on until complete. 4. The majority of users indicate that the textual content is of greatest value, however, a somewhat higher quality reproduction could be made from "photographs" if essential to the understanding of the dissertation. Silver prints of "photographs" may be ordered at additional charge by writing the Order Department, giving the catalog number, title, author and specific pages you wish reproduced. 5. PLEASE NOTE: Some pages may have indistinct print. Filmed as received. Xerox University Microfilms 300 North Zeeb Road Ann Arbor, Michigan 48106 76-16,234 SCHUSTER, William John, 1948- THIRTEEN-COLOR PHOTOMETRY OF SUBDWARFS. The University of Arizona, Ph.D., 1976 Physics, astronomy & astrophysics Xerox University Microfilms, Ann Arbor, Michigan 48106 THIRTEEN-COLOR PHOTOMETRY OF SUBDWARFS by William John Schuster A Dissertation Submitted to the Faculty of the DEPARTMENT OF ASTRONOMY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 19 7 6 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE I hereby recommend that this dissertation prepared under my direction by William John Schuster entitled Thirteen-Color Photometry of Subdwarfs be accepted as fulfilling the dissertation requirement of the degree of Doctor of Philosophy Dissertatioi^Director Date After inspection of the final copy of the dissertation, the follov7ing members of the Final Examination Committee concur in its approval and recommend its acceptance:'" f . 12- i4-JS J 7S~ S- T=S^t^ This approval and acceptance is contingent on the candidate's adequate performance and defense of this dissertation at the final oral examination. The inclusion of this sheet bound into the library copy of the dissertation is evidence of satisfactory performance at the final examination. STATEMENT BY AUTHOR This dissertation has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to bor­ rowers under rules of the Library. Brief quotations from this dissertation are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or re­ production of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his judgment the proposed use of the material is in the in­ terests of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED ACKNOWLEDGMENTS I would like especially to thank Dr. Harold L. Johnson for sug­ gesting this dissertation topic to me and for the many helpful discussions we have had together. I am also very grateful to Dr. S. E. Strom and to R. I. Mitchell for their assistance, encouragement, and patience during the last two years. I am indebted to Dr. Arcadio Poveda, Director del Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, for allowing me to work at the Mexican National Observatory during the course of my observ­ ing for this dissertation. I also wish to thank Dr. Enrique Daltabuit for his support and concern. Drs. W. Fitch and R. Thompson have been very helpful in reading the preliminary drafts of this dissertation and in improving the final copy. It is a pleasure to thank Drs. B. J. Bok, T. Swihart, W. Tifft, R. White, P. Strittmatter, R. Williams, A. Pacholczyk, and R. Weymann for making my life as a graduate student as interesting as it has been. Last, but certainly not least, I would strongly like to thank the excellent staff at the Mexican National Observatory. Rene Murillo, Gaspar Sanchez, Eduardo Lopez, and Jose Murillo, whose help made the observing considerably easier, deserve special thanks. iii TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS vi LIST OF TABLES ix ABSTRACT xi CHAPTER 1. INTRODUCTION 1 Problems of Subdwarf Interpretations 2 Photometric Sensitivity and the Calibration of Photometric Indices . 7 What is to be Learned About Subdwarfs 9 2. INSTRUMENTATION AND PHOTOMETRIC TECHNIQUES 11 Instrumentation . H Techniques of Photometry 19 Specific Problems 23 3. REDUCTION OF THE PHOTOMETRY 27 The Computer Program 27 What the Program Does 28 4. THE OBSERVATIONS 33 The Subdwarfs 33 Hyades, G Stars, YY Gem, and BS5270 40 Quality of the Observations 4.4 5. THE SENSITIVITY OF 13-COLOR INDICES TO BASIC STELLAR ATMOSPHERIC PARAMETERS 54 Derivation of Mean Hyades Colors ..... 55 Blanketed Model Atmospheres 58 Blanketing and Luminosity-difference Curves 62 iv V TABLE . OF CONTENTS—Continued Page Two Important Color-color Diagrams 97 Some Preliminary Conclusions About Subdwarfs ..... 105 6. CALIBRATION OF THE 13-COLOR INDICES 113 Composition Calibration 113 Effective Temperature Calibration 127 Bolometric Magnitude Calibration ..... 142 Surface Gravity Calibration 148 7. ANALYSIS AND DISCUSSION 160 Mbol versus Te Diagram 160 The Evolutionary Status of Subdwarfs ... 184 Masses of Subdwarfs 204 8. CONCLUSIONS 210 What We Have Learned 210 Prospects for Further Research 215 REFERENCES 219 LIST OF ILLUSTRATIONS Figure 1. 45-63 versus R-I 65 2. Theoretical 45-63 versus T curves 66 e 3. The average observational blanketing curve for the sub- dwarfs of group 1 . 74 4. The average observational blanketing curve for the subr- dwarfs of group 2 75 5. The average observational blanketing curve for the sub- dwarfs of group 3 76 6. The average observational blanketing curve for the sub- dwarfs of group 4 77 7. The average observational blanketing curve for the sub- dwarfs of group 5 78 8. The average observational blanketing curve for the sub- dwarfs of group 6 79 9. The average observational blanketing curve for the sub- dwarfs of group 7 (circles) plus the blanketing curve for BS 4550 (squares) 80 10. Theoretical blanketing curves for Te = 6500° and log g = 4.5 , 83 11. Theoretical blanketing curves for T = 6000° and log g = 4.5 ? 84 12. Theoretical blanketing curves for T = 5500° and log = 4.5 ? 85 13. A(37-52) versus (T ) for groups 1, 2, 3 and 5 and for BS 4550 . .e. aY® 86 14. Observational luminosity-difference curves for two F giants . 89 vi vii LIST OF ILLUSTRATIONS—Continued Figure Page 15. Observational luminosity-difference curves for G giants . 90 16. Observational luminosity-difference curves for late-G and early-K giants 91 17. Theoretical luminosity-difference curves for Tg = 6500° . 92 18. Theoretical luminosity-difference curves for Tg = 6000° . 93 19. Theoretical luminosity-difference curves for T = 5500° . 94 e 20. An observational blanketing curve for cool giants .... 98 21. Observational blanketing curves for BS 5270 99 22. 37-45 versus 45-63 ......... 100 23. 37-45 versus 45-63 for evolved stars 101 24. G versus 45-63 104 25. The average observational blanketing curve for seven F-type main sequence stars . 108 26. 6(37-45)corrected versus CFe/Hl 118 27. Lines of constant composition in the 37-45 versus 45-63 diagram 122 28. 58-99 versus R-I . 130 29. Theoretical 58-99 versus T curves , 131 e 30. The observational calibration of 45-63 versus T 136 e 31. The observational calibration of 58-99 versus T 137 e 32. The m, ,-(63) , versus 45-63 calibration 144 bol obs 5 63 33. 63-K versus (^ - )Hyades 34. Theoretical and observational relative energy distribu­ tions for +26°2606 152 viii LIST OF ILLUSTRATIONS—Continued Figure Page 35. Theoretical and observational relative energy distribu­ tions for HD 84937 153 36. Theoretical and observational relative energy distribu­ tions for the Hyades dwarf, H57 156 37. Log g versus "luminosity class" for stars in the range 6500° > T > 6000° 157 — e ~ 38. Log g versus 6G 158 39. M, , versus T 164 bol e 40. M, , versus T for mild subdwarfs and field stars .... 173 bol e 41.