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T He Cool Stellar P Opulations of E Arly-T Y Pe G T h e C o ol S t e l l a r P o pu l a t io n s o f E a r l y -T y p e G a l a x ie s a n d t h e G a l a c t ic B ulge dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Mark Lee Houdashelt, 3|C $ J ) t + $ The Ohio State University 1995 Dissertation Committee: Approved by Prof. Jay A. Frogel Prof. Kristen Sellgren /J (J Advisor Prof. Donald M. Temdrup Department of Astronomy ONI Number: 9533992 UMI Microform 9533992 Copyright 1995, by UMI Company. All rights reserved. This microform edition is protected against unauthorized copying under Title 17, united States Code. UMI 300 North Zeeb Road Ann Arbor, MI 48103 To Mom and Tim ii A cknowledgements First and foremost, I would like to express my deepest appreciation to my mother, Darlene, and my brother, Tim, for their unwavering support before, during, and (hopefully) after my graduate studies. Without them, I would not have achieved as much as I have nor be as happy as I am. Thank you, Mom amd Tim, for all that you have done for me. Obviously, I am deeply indebted to my advisor, Jay Frogel, for his support (both financial and otherwise), his scientific expertise and his belief in my abilities. He suggested the initial dissertation project to me and helped me to redefine it along the way, always remaining positive and encouraging. I would also like to thank the other members of my dissertation committee, Don Terndrup and Kris Sellgren, for their endless patience and understanding and for their thorough review of my research and written dissertation. A special thanks go to Bob Wing, who read this dissertation and became a substitute member of my defense committee on very short notice. Rick Pogge is acknowledged for many helpful scientific discussions, and Brad Peterson and Jerry Newsom were always positive and concerned for my welfare. I would like to thank Pat Osmer as well; he was instrumental in making the special arrangements necessary for me to be able to complete this work. I would like to express my gratitude to the Ohio State University and Lowell Observatory for granting me the observing time required to undertake this dissertation research. I owe Mark Wagner and Ray Bertram a great debt for their assistance at Lowell Observatory. In addition, Bob Millis went out of his way to make my visits there as productive and comfortable as possible. I would also like to thank the staff at Kitt Peak National Observatory for their outstanding service during my observing time there - Richard Elston is especially noted for his time and advice regarding the use of the CRSP instrument. I can’t express enough gratitude to the many friends I have made while at The Ohio State University. Many of the “old-timers” from the astronomy department have moved on to bigger and better things: Andy Karam, Mike Fisher, Pedro Saizar, Bill Welsh, Tereasa Brainerd, Cathy Mansperger, Kirk Korista, and Phil Martell. Current OSU graduate students Bob Blum, Glenn Tiede, Leslie Kuchinski, Mike Owen, Anita Krishnamurthi, Nancy Jo Lame, Ani Thakar, Babar Ali and Cheongho Han are thanked for their valuable scientific discussion but are most appreciated for their friendship and encouragement. I will miss them and wish them all the best. Other close friends who were critical to my success include Steve Long, Jens Villumsen, Mark Duell, Fernando Fischer and Rosa Gimenez. Karen Keppler is owed a very special thanks - she was always there to help and was a constant source of optimism, support and chocolate. To the members of CURB (Clean-Up and Recycling Backers), my gratitude for giving me the opportunity to do something worthwhile besides astronomy and to give something back to the community in which I lived. Shirley Cotter, Reardon Young, Mark Carter, Tom Brown et al. are a very special group of caring people. Among my many CURB-mates, I would especially like to thank Anthony Fabro for his friendship and for the rides he provided to CURB meetings and other recycling activities. Finally, I am indebted to Brenan’s Coffee Shop (and Yogurt Oasis) for supplying the caffeine necessary for survival on those late nights at the office and for providing various other forms of inspiration and motivation! Damon’s Restaurant and NTN trivia also provided much-needed diversions from the daily grind. V it a May 9, 1959 .......................................................... Born - Lincoln, NE 1983 .......................................................................... B.S. Chemistry, Colorado State Uni­ versity, Fort Collins, Colorado 1988 ................................. ........................................ B.S. Physics, Colorado State Univer­ sity, Fort Collins, Colorado 1988-1990 ................................................................ University Fellow, The Ohio State Uni­ versity, Columbus, Ohio 1990-1992 ................................................................ Graduate Research Associate, The Ohio State University, Columbus, Ohio 1992-1993 ................................................................ Presidential Fellow, The Ohio State University, Columbus, Ohio 1993-1994 ................................................................ Graduate Research Associate, The Ohio State University, Columbus, Ohio 1995 ..........................................................................Graduate Teaching Associate, The Ohio State University, Columbus, Ohio Publications Research Publications Papers Published in Refereed Journals “Giants in Old Open Clusters: Temperatures, Luminosities and Abundances from Infrared Photometry,” Houdashelt, M. L., Frogel, J. A., and Cohen, J. G. 1992, AJ, 103, 163. Contributions to Published Conference Proceedings “A Comparison of the Near-Infrared Spectral Features of Early-Type Galaxies in the Coma Cluster, the Virgo Cluster and the Field,” Houdashelt, M. L., and Frogel, J. A., in The Evolution of Galaxies and Their Environment, Proceedings of the Third Teton Summer School on Astrophysics, NASA Conf. Publ. 3190, ed. D. Hollenbach, H. Thronson and J- M. Shull, p. 31, 1993, (contributed poster). Published Unrefereed Abstracts “A Comparison of the Near-Infrared Spectral Features of Early-Type Galaxies in the Virgo and Coma Clusters,” Houdashelt, M. L., Columbus AAS meeting, June 1992. BAAS, 24, 808. “The Red Supergiants of NGC 2100,” Wing, R. F., and Houdashelt, M. L., Columbus AAS meeting, June 1992. BAAS, 24, 773. “Giants in Old Open Clusters: Temperatures, Luminosities and Abundances from Infrared Photometry,” Houdashelt, M. L., Frogel, J. A., and Cohen, J. G., Atlanta AAS meeting, January 1991. BAAS, 23, 1473. Fields of Study Major Field: Astronomy Studies in: Stellar Populations Prof. J. Frogel, Prof. D. Terndrup Star Clusters Prof. J. Frogel, Prof. R. Wing Early-Type Galaxies Prof. J. Frogel, Prof. D. Terndrup Spectroscopy Prof. J. Frogel, Prof. D. Terndrup T a b l e o f C o n t e n t s DEDICATION ...................................................................................................................... ii ACKNOWLEDGEMENTS .............................................................................................. iii VITA ........................................................................................................................................ vi LIST OF TABLES ................................................................................................................ xi LIST OF FIGURES ............................................................................................................ xiv CHAPTER PAGE I INTRODUCTION ...................................................................................................... 1 1.1 Photometry of Early-Type G alaxies ........................................................... 4 1.1.1 The Color-Magnitude R elation ..................................................... 4 1.1.2 Color Gradients in Early-Type Galaxies ...................................... 7 1.1.3 Colors and Stellar Populations ..................................................... 8 1.2 Spectroscopy of Early-Type Galaxies ........................................................ 8 1.3 This Dissertation ........................................................................................... 9 II OBSERVATIONS AND DATA REDUCTION .................................................. 12 2.1 The Galaxy Sam ple ............................................................................... 12 2.1.1 Data Taken from the Literature ...................................................... 13 2.2 Red Spectroscopy .............................................................................................. 15 2.2.1 Observations ........................................................................................ 16 2.2.2 Data Reduction ..................................................................................... 18 2.2.3 Near-Infrared Spectroscopy ............................................................ 24 III RED SPECTRAL FEATURES IN EARLY-TYPE GALAXIES ..... 33 3.1 Red Spectral Features in Stars ................................................................ 33 3.1.1 Atomic Lines ...................................................................................... 34 3.1.2 Molecular Bands ................................................................................ 38 3.2 Measurement of Spectral Features in Galaxies ..................................... 39 3.2.1 Definitions of the Indices ..............................................................
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