DEVELOPMENT OF A LINE LIST FOR AUTOMATION OF STELLAR ABUNDANCE ANALYSIS A Thesis by DAVID GRIBBLE Submitted to the Graduate School at Appalachian State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE August 2018 Department of Physics and Astronomy DEVELOPMENT OF A LINE LIST FOR AUTOMATION OF STELLAR ABUNDANCE ANALYSIS A Thesis by DAVID GRIBBLE August 2018 APPROVED BY: Michael Briley, Ph.D. Chairperson, Thesis Committee Richard Gray, Ph.D. Member, Thesis Committee Courtney McGahee, Ph.D. Member, Thesis Committee Michael Briley, Ph.D. Chairperson, Department of Physics and Astronomy Michael J. McKenzie, Ph.D. Dean, Cratis D. Williams School of Graduate Studies Copyright by David Gribble 2018 All Rights Reserved Abstract DEVELOPMENT OF A LINE LIST FOR AUTOMATION OF STELLAR ABUNDANCE ANALYSIS David Gribble B.S., University of California, Davis M.S., Appalachian State University Chairperson: Michael Briley, Ph.D. Studies of abundances in stars have a wide range of application to many topics in stellar, galactic, and nuclear astrophysics. By looking at abundances of elements in stars and clusters, we can draw conclusions about the histories of those clusters and of the stars within them. And by looking at stars that may not match our current theories of stellar evolution, we can close some of the gaps in our understanding of the evolution and lifecycles of stars. As surveys get increasingly larger and generate progressively more data, having tools that facilitate the automatic processing of these large data sets becomes ever more desirable. In this paper, we develop a “line list” of 428 transitions necessary for detailed abundance analyses of high-resolution spectra, and then present a semi-automated method for determining abundances from equivalent width measurements through the use of the line list with the spectral-line fitting software DAOSpec, the MARCS grid of model atmospheres, and the spectral-line analysis software MOOG. We demonstrate our line list and abundance analysis tools on two different stars, NGC 6940 101 and IC 4756 14. We present our derived stellar atmosphere parameters for those stars and give detailed abundance analyses. We then iv compare these results to those found in other studies to demonstrate the quality and reliability of our tools. v Acknowledgments This work was made possible with funding and support from NASA/North Carolina Space Grant and with observations taken at McDonald Observatory. The author would like to thank Peter Stetson, for helpful correspondences and code suggestions, and Michael Briley for contributing observational data, and contributing the section in Chapter 2.1 describing those observations. The author expresses his gratitude to Michael Briley, Richard Gray, and Courtney McGahee for their support as well as their insightful comments and suggestions for improving the paper. This research made use of the IRAF, DAOSpec, MOOG, and MARCS software packages. v i Dedication To all of the scientists who have inspired, supported, and encouraged me over the years, without whom, I would not be where I am today. People who give unconditionally, with no expectation of a return, simply because they sincerely care about the next generation of scientists. I hope to be able to pay those gifts forward in some way. Ron Mickens, Tom Cahill, Charles Ferguson, Sid Clements, Patricia Boeshaar. To Edward Bouchet. To Bryce Case Jr. And to Henry Mosely. vi i Table of Contents Abstract .............................................................................................................................. iv Acknowledgments .............................................................................................................. vi Dedication ......................................................................................................................... vii Chapter 1. Introduction ........................................................................................................1 Chapter 2. Justification and Literature Review ....................................................................4 Chapter 3. Description of Research .....................................................................................9 Chapter 4. Results ..............................................................................................................22 Chapter 5. Conclusion ........................................................................................................29 Chapter 6. Bibliography .....................................................................................................31 Appendix A: line_data_sort.c ............................................................................................34 Appendix B: line_list_cancat_sort.c ..................................................................................36 Appendix C: add_trigger_char_for_DAO_Input.c ............................................................39 Appendix D: line_list_concact_sort_NGC6940.c .............................................................42 Appendix E: line_list_concact_sort_IC4765_91171.c ......................................................45 Appendix F: line_list_full_sorted.txt .................................................................................48 Appendix G: line_list_NGC6940_full_sorted.txt ..............................................................57 Appendix H: line_list_IC4765_91171_full_sorted.tct .......................................................64 Appendix I: model.NGC_6940101 ....................................................................................71 Appendix J: model.IC4765_91171 ....................................................................................73 vi ii Vita .....................................................................................................................................75 ix Chapter 1. Introduction Studies of abundances in stars have a wide range of application to many topics in stellar, galactic, and nuclear astrophysics. By looking at abundances of elements in stars and clusters, we can draw conclusions about the histories of those clusters and of the stars within them. Broadly, this research is concerned with closing the gaps in our understanding of the evolution and lifecycles of stars by looking at stars that may not match our current theories of stellar evolution. As surveys become increasingly larger and generate progressively more data, having tools that facilitate the automatic processing of these large data sets becomes ever more desirable. In this paper, we develop a “line list” — a reference list of atomic transitions corresponding to various absorption lines, and the excitation potentials and transition probabilities associated with those transitions — necessary for detailed abundance analyses, and then present a semi-automated method for determining abundances from equivalent width measurements through the use of the line list with multiple software packages. Through this process, we also set up tools useful to accommodate the processing of other large spectroscopic data sets. We test our line list and abundance analysis tools on two different program stars, NGC 6940 101 and IC 4756 14. We present our derived stellar atmosphere parameters for those stars and give detailed abundance analyses. We then compare these results to those found in other studies to demonstrate the quality and reliability of our tools. We use observations taken with the high-resolution spectrograph on the 2.7-meter telescope at the McDonald Observatory, and apply the automated spectral-line fitting 1