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Xerox University Microfilms 300 North ZM b Road Ann Arbor, Michigan 48100 74-24,296 BARNHART,_ Ph. Jl1p Everett, 1930- PHOTOELECTRIC SOLAR LIMB SCANS FOR DETERMINING MEAN CHROMOSPHERIC STRUCTURE. The Ohio State University, Ph.D., 1974 Astronony University Microfilms, A XEROX Company, Ann Arbor, Michigan THIS DISSERTATION HAS BEEN MICROFILMED EXACTLY AS RECEIVED. PHOTOELECTRIC SOLAR LIMB SCANS FOR DETERMINING MEAN CHROMOSPHERIC STRUCTURE DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Philip Everett Barnhart, B. A., M. A. * # ★ * * The Ohio State University 1974 Reading Committee: Approved By Walter E. Mitchell, Jr Geoffrey Keller Qtojtiui-i. AAddvviisseerr (I Gerald Newsom Department of Astronomy ACKNOWLEDGMENTS It is not a difficult task to express my gratitude to the many people who have come together directly and indirectly to make this effort possible. Some, like the inspirational teachers along the way who were able to keep my interest alive, will have to settle for the general, nameless, "Thank You" to which 1 must resort in the interest of space utilization. Their numbers are legion. Others deserve special mention because they have contributed so meaningfully that this work would not have been completed without them. Inspiration for the whole thing grew out of the op­ portunity I have had over the years to work with Walter E. Mitchell, Jr. He was willing to let me do it my way and when he pointed out the better way to do it he made it seem as if I had done it all myself. For this I shall always be grateful. Enough can never be said about the warm, generous and always competent receptions I received from the Kitt Peak Observatory staff. In the Tucson headquarters or on the mountain I was made to feel welcome and was afforded the best of help. I greatly value the untiring efforts ii of Chuck Slaughter and Dick Aikens for putting together an efficient data acquisition program. As if that was not enough they provided valuable assistance and encouragement at the telescope. I also appreciate the stimulating dis­ cussions with A. Keith Pierce, William Livingston and Jim Brault. They make being a member of the astronomical community a pleasure. Being faced with such a volume of data 1 was led to conclude that I would never wade through it without invaluable help from the masters of the machines. I am deeply indebted to the staff of the Otterbein College Data Center and that of the Battelle Memorial Institute for their patience in enduring the seemingly interminable outpouring of solar data. In particular I must acknowledge the tremendous help given me by Dennis Lohr who turned some of my vague, fuzzy ideas into a beautifully workable data processing achievement. There is much of him in these limb scans. Among several who helped me work up the 1500 plots necessary to display what I thought I needed to see I must take particular note of my dear wife, Esther. She decided that if I was ever going to finish the job, she would have to do the dirty work. iii A whole student generation has seen less of me them we would like. For that I apologize. For four years now my children have claimed to be fatherless. Starting this year they may see that it is really all for them. iv VITA September 2, 1930 . B o m - Indianapolis, Indiana 1952................ B. A., Manchester College, North Manchester, Indiana 1955................ M. A., Indiana University, Bloomington, Indiana 1955 - 1964 ........Research Associate, Research Foundation, The Ohio State University, Columbus, Ohio 1959 - 1962 ........Instructor (part time) Dept. of Physics, Otterbein College, Westerville, Ohio 1962 - ........ Assistant Professor, Department of Physics and Astronomy, Otterbein College, Westerville, Ohio (Chairman, 1962 - 1970) PUBLICATIONS "Direct Observation of Element Motion in Stellar Shadow Patterns," Barnhart, P. E., Protheroe, W. M. and Galli, J., Jour. Opt. Soc. Amer. 46, 904, 1956. "The Photoelectric Determination of the Direction and Velocity of Motion in the Scintillation Layer," Barnhart, P. E., Astron. Joum., 62, 3, 1957. "Design of a Photoelectric Photometer for Observing the Distribution of Light Intensity in Telescopic Images," Protheroe, W. M., Barnhart, P. E. and Galli, J., Chapter 10, Final Report Contract AF 19(704) - 1409, AFCRC, Elec­ tronics Directorate, Laurence G. Hanscom Field, Bedford, Mass. 1956. v "Description of a Device for Computing Statistical Proper­ ties of Stellar Shadow Pattern," Keller, G., Barnhart P. E. and Angelone, A., Scientific Report 1, Contract AF 19(604)-1954, AFCRC Geophysics Research Directorate, Laurence G. Hanscorn Field, Bedford, Mass. 1957. "Investigation of Upper Air Turbulence by the Method of Analysing Stellar Scintillation Shadow Patterns," Barnhart, P. E., Keller, G., and Mitchell, W. E. Jr. Final Technical Report, Contract AF 19(604) - 1954, AFCRC, Geophysics Directorate, Laurence G. Hanscom Field, Bedford, Mass. 1959. "A Program of Stellar Narrow Band Infrared Photometry," Barnhart, P. E. and Hynie, W. H., Mem. Soc. Roy. Sci. Liege, cinguieme serie, Tome IX, 425, 1964. "Infrared Stellar Photometry," Barnhart, P. E. and Mitchell, W. E., Jr., Contributions from the Perkins Observatory, Series II No. 16, 1966. FIELDS OF STUDY Major Field: Astronomy Studies in Atmospheric Seeing. Professors G. Keller and W. E. Mitchell, Jr. Studies in Infra-Red Stellar Irradiances. Professor W. E. Mitchell, Jr. Studies in Solar Chromospheric Structure. Professor H. E. Mitchell, Jr. vi TABLE OP CONTENTS Page ACKNOWLEDGMENTS................................... ii VITA ............................................. V TABLE OF CONTENTS................................... vii LIST OF T A B L E S ................................... ix LIST OF F I G U R E S ................................... X LIST OF SYMBOLS ..................................... xiv I. INTRODUCTION ................................... 1 Early History of Chromospheric Study .... 1 Discovery and Use of Flash Spectrum .... 2 Chromospheric Structure ................... 8 Chromospheric Spectral Analysis .......... 9 Mean Structure Outside Eclipse ............. 10 II. THE NEED FOR CHROMOSPHERIC INTENSITY MEASUREMENT 15 Proposed Technique of Observation .... 24 Magnitude of the Observing Problem .... 26 III. DESCRIPTION OF THE OBSERVING P R O G R A M ......... 32 Results of Preliminary R u n ................. 34 Description of Apparatus................... 45 Geometry of the Solar Limb ........ 51 Technique of Observation ................. 52 Method of Data Analysis ................. 62 The Search for Invariant Parameters . 76 Determination of Seeing Half-Width .... 92 Technique for Locating Limb Points .... 94 Status of the Solar L i m b ................... 99 vii Page Presentation of Observed D a t a .............101 Observations of the Balmer Lines .... 104 Effects of Defocussing ................ Ill Metal Lines ............................... 116 Helium L i n e s ............................. 147 IV. CONCLUSIONS ................................. 163 Value of the Mohler Technique.............163 Specific Proposals ..................... 167 APPENDIX 1. Normalization Procedure................... 173 2. Scan Rate Calibration ................... 185 3. Two Dimensional Scattering Function .... 192 BIBLIOGRAPHY....................................... 196 viii LIST OF TABLES Page Table 1 Theoretical Emission Source Heights 16 Table 2 Chromospheric Limb Heights 19 Table 3 List of Proposed Chromospheric Lines 33 Table 4 Lines Added at the Telescope 33 Table 5 Data Relevant to August 1970