Brigham Young University BYU ScholarsArchive Theses and Dissertations 2007-03-06 Development of an H-Alpha Index for the Detection of PMS Candidates in Young Open Clusters Liberty Rae Evanko Brigham Young University - Provo Follow this and additional works at: https://scholarsarchive.byu.edu/etd Part of the Astrophysics and Astronomy Commons, and the Physics Commons BYU ScholarsArchive Citation Evanko, Liberty Rae, "Development of an H-Alpha Index for the Detection of PMS Candidates in Young Open Clusters" (2007). Theses and Dissertations. 1163. https://scholarsarchive.byu.edu/etd/1163 This Dissertation is brought to you for free and open access by BYU ScholarsArchive. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Development of an H alpha index for the detection of pms candidates in young open clusters by Liberty Rae Evanko A dissertation submitted to the faculty of Brigham Young University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Physics and Astronomy Brigham Young University April 2007 BRIGHAM YOUNG UNIVERSITY GRADUATE COMMITTEE APPROVAL of a dissertation submitted by Liberty Rae Evanko This dissertation has been read by each member of the following graduate committee and by majority vote has been found to be satisfactory _______________________________ _____________________________________ Date Benjamin J. Taylor, Chair _______________________________ _____________________________________ Date J. Ward Moody _______________________________ _____________________________________ Date Ross L. Spencer _______________________________ _____________________________________ Date Eric Hirschmann _______________________________ _____________________________________ Date Bryan G. Peterson BRIGHAM YOUNG UNIVERSITY As chair of the candidate’s graduate committee, I have read the dissertation of Liberty R. Evanko in its final form and have found that (1) its format, citations, and bibliographical style are consistent and acceptable and fulfill university and department style require- ments; (2) its illustrative materials including figures, tables, and charts are in place; and (3) the final manuscript is satisfactory to the graduate committee and is ready for sub- mission to the university library. _____________ ______________________________________________________ Date Benjamin J. Taylor Chair, Graduate Committee Accepted for the Department ______________________________________________________ Ross L. Spencer Graduate Coordinator, Department of Physics and Astronomy Accepted for the College ______________________________________________________ Thomas W. Sederberg Associate Dean, College of Physical and Mathematical Sciences ABSTRACT DEVELOPMENT OF AN Hα INDEX FOR THE DETECTION OF PMS CANDIDATES IN YOUNG OPEN CLUSTERS Liberty Rae Evanko Department of Physics and Astronomy Doctor of Philosophy One phase of formation of medium- and low-mass stars is the optically visible phase known as the pre-main-sequence or PMS phase. In order to further the understanding of this phase, more of these PMS objects need to be identified and classified. Previous techniques have used photometry to identify possible PMS objects by their characteristic Hα emission. Once identified these objects can be studied spectroscopically yielding complete PMS classification. This study develops a method to locate these emission objects that overcomes two limitations of previous techniques. The first limitation is the need for the creation of reddening maps. It is eliminated by the creation of a reddening free Hα wide/narrow index for the selection of emission objects. The second limitation is the requirement of the creation of mosaics to study the entire region of interest. This limitation is overcome by the construction of a wide-angle observation facility. This makes it possible to obtain the entire region of interest in a single frame. Once tested to ensure the validity of the method, the wide-angle Hα wide/narrow procedure is applied to several young open clusters. The development of the index and the results of its application to the clusters are presented. Also, an examination into how the results can be used to address some of the questions currently surrounding the PMS is included. Finally, a guideline for the implementation of the method into future studies is discussed. ACKNOWLEDGEMENTS I would like to acknowledge all the professors and fellow students who assisted me in the completion of this project. It is truly a collaboration of many talented individuals. I would like to thank my biggest support throughout the duration of this project, my husband Ben. Thanks for always believing in me and the countless sacrifices made to make this possible. Finally, I dedicate this work to my father. May he receive peace knowing I achieved his dreams for me. Table of Contents Table of Contents.........................................................................................vii List of Figures ...............................................................................................ix List of Tables ...............................................................................................xvi 1. Introduction...............................................................................................1 2. Background on Pre-Main-Sequence Stars .............................................4 2.1 T Tauri Stars ....................................................................................................... 4 2.2 Herbig Ae/Be ....................................................................................................... 7 2.3 Mass Segregations............................................................................................... 8 3. Previous PMS Surveys ............................................................................10 3.1 Spectroscopic Surveys .......................................................................................... 11 3.2 Photometric Surveys............................................................................................. 13 4. Hα Index Development...........................................................................23 4.1 Introduction........................................................................................................... 23 4.2 Photometric and Spectroscopic Tests.................................................................. 27 4.2.1 Photometry....................................................................................................... 27 4.2.2 Spectroscopy.................................................................................................... 30 4.3 Increasing the sensitivity ...................................................................................... 41 5. Application ..............................................................................................45 5.1 Photometry Reduction Process............................................................................ 46 5.2 Analysis and Selection Criteria............................................................................ 50 5.3 Results .................................................................................................................... 52 5.3.1 NGC 2244 ........................................................................................................ 54 5.3.2 NGC 2264 ........................................................................................................ 62 5.3.3 NGC 6530 ........................................................................................................ 70 5.3.4 NGC 6611 ........................................................................................................ 78 5.3.5 Trumpler 37 ..................................................................................................... 86 5.4 Summary and Suggestions for Future Work ..................................................... 94 vii 6. Conclusion................................................................................................98 7. Bibliography ..........................................................................................101 A. Summary of Stellar Evolution and Diagnostic Tools .......................106 A.1 Stellar Evolution................................................................................................. 106 A.1.1 Overview...................................................................................................... 106 A.1.2 Young Stellar Systems.................................................................................. 110 A.1.2.1 Associations ........................................................................................... 113 A.1.2.2 Clusters................................................................................................... 115 A.1.3 Protostars....................................................................................................... 119 A.1.4 PMS Objects ................................................................................................. 122 A.1.4.1 Emission Line Profiles........................................................................... 123 A.1.4.2 Jets and Molecular Outflows.................................................................. 127 A.2 Diagnostic Tools ................................................................................................