FOLLOWING CARBON’S EVOLUTIONARY PATH: FROM NUCLEOSYNTHESIS TO THE SOLAR SYSTEM by Stefanie Nicole Milam _____________________ Copyright © Stefanie Nicole Milam 2007 A Dissertation Submitted to the Faculty of the DEPARTMENT OF CHEMISTRY In Partial Fulfillment of the Requirements For the Degree of DOCTOR OF PHILOSOPHY In the Graduate College THE UNIVERSITY OF ARIZONA 2007 2 THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Dissertation Committee, we certify that we have read the dissertation prepared by Stefanie Nicole Milam entitled Following Carbon’s Evolutionary Path: From Nucleosynthesis to the Solar System and recommend that it be accepted as fulfilling the dissertation requirement for the Degree of Doctor of Philosophy _______________________________________________________________________ Date: October 24, 2007 Dr. Lucy M. Ziurys _______________________________________________________________________ Date: October 24, 2007 Dr. Stephen Kukolich _______________________________________________________________________ Date: October 24, 2007 Dr. Andrei Sanov _______________________________________________________________________ Date: October 24, 2007 Dr. Christopher K. Walker _______________________________________________________________________ Date: October 24, 2007 Dr. Susan Wyckoff Final approval and acceptance of this dissertation is contingent upon the candidate’s submission of the final copies of the dissertation to the Graduate College. I hereby certify that I have read this dissertation prepared under my direction and recommend that it be accepted as fulfilling the dissertation requirement. ________________________________________________ Date: October 24, 2007 Dissertation Director: Dr. Lucy M. Ziurys 3 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 borrowers 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 reproduction of this manuscript in whole or in part may be granted by the copyright holder. SIGNED: Stefanie Nicole Milam 4 ACKNOWLEDGEMENTS I would like to first acknowledge my advisor, Dr. L. M. Ziurys, for her support and guidance throughout my graduate career. She has helped me achieve numerous tasks that surpassed even my expectations. Many thanks to Drs. S. Wyckoff, N. Woolf, A. Remijan, and A. Apponi for guidance, patience, mentorship, and support over the last few years. These individuals never gave up on me and helped me through even the roughest of times. I would also like to recognize key individuals in my education including my committee members, A. Sanov, S. Kukolich, and C. Walker, as well as my undergraduate mentors D. Hanna and Y. Chiang. These people have given me the education and guidance I need for a career in the physical sciences. Recognition is given to my fellow graduate students C. Savage, P. Sheridan, and M. Flory for their continued patience, support, and friendship. Also, a special thanks goes to the Arizona Radio Observatory engineers and staff for all their hard work to keep the telescopes in excellent condition. Finally, a special acknowledgement goes to my family; my mother and father for their support in my decision to pursue this degree and my husband, Lawrence, for absolutely everything. 5 TABLE OF CONTENTS LIST OF FIGURES ........................................................................................................... 7 LIST OF TABLES ............................................................................................................. 8 ABSTRACT ....................................................................................................................... 9 CHAPTER 1. INTRODUCTION ................................................................................... 11 CHAPTER 2. TELESCOPES …..................................................................................... 13 a. Arizona Radio Observatory 12 m .................................................................. 15 b. Arizona Radio Observatory Submillimeter Telescope .................................. 16 CHAPTER 3. FORMATION OF CARBON: 12C/13C IN CIRCUMSTELLAR ENVELOPES ............................................................................................................. 18 a. CN (X 2Σ+) ..................................................................................................... 20 b. 12C/13C ............................................................................................................ 21 c. Implications and Nucleosynthesis .................................................................. 26 d. VY Canis Majoris .......................................................................................... 30 e. Planetary Nebulae .......................................................................................... 32 CHAPTER 4. CARBON IN THE INTERSTELLAR MEDIUM: 12C/13C RATIOS ...... 36 a. 12CN/13CN N=1→0 ........................................................................................ 37 b. 12CN/13CN From Multiple Transitions .......................................................... 40 CHAPTER 5. CARBON IN THE SOLAR SYSTEM: COMETS .................................. 45 a. H2CO and CO Extended Source .................................................................... 47 b. Other Organics and Planetary Distribution .................................................... 49 CONCLUSIONS ............................................................................................................. 51 APPENDIX A. HCO+ OBSERVATIONS TOWARDS COMET HALE-BOPP (C/1995 O1): ION-MOLECULE CHEMISTRY AND EVIDENCE FOR A VOLATILE SECONDARY SOURCE .................................................. 52 APPENDIX B. THE 12C/13C ISOTOPE GRADIENT DERIVED FROM MILLIMETER TRANSITIONS OF CN: THE CASE FOR GALACTIC CHEMICAL EVOLUTION ......................................................................................... 62 APPENDIX C. FORMALDEHYDE IN COMETS C/1995 O1 (HALE-BOPP), C/2002 T7 (LINEAR) AND C/2001 Q4 (NEAT): INVESTIGATING THE COMETARY ORIGIN OF H2CO .......................................................... 70 6 TABLE OF CONTENTS – Continued APPENDIX D. CHEMICAL COMPLEXITY IN THE WINDS OF THE OXYGEN- RICH SUPERGIANT STAR VY CANIS MAJORIS ............................ 80 APPENDIX E. DETECTION OF NaCl TOWARDS IK Tau AND VY CMa: OXYGEN- RICH MASS LOSS WITH A PINCH OF SALT ................................... 87 APPENDIX F. CONSTRAINING PHOSPHORUS CHEMISTRY IN CARBON- AND OXYGEN-RICH CIRCUMSTELLAR ENVELOPES: OBSERVATIONS OF PN, HCP, AND CP ........................................................................... 92 APPENDIX G. THE DISTRIBUTION, EXCITATION AND FORMATION OF COMETARY MOLECULES: METHANOL, METHYL CYANIDE AND ETHYLENE GLYCOL ............................................................... 120 APPENDIX H. A SURVEY OF CIRCUMSTELLAR 12C/13C ISOTOPE RATIOS DERIVED FROM CN AND CO: NUCLEOSYNTHESIS IN VARIOUS TYPES OF STARS ............................................................................... 155 APPENDIX I. THE CN N=2→1 ISOTOPE GRADIENT: FURTHER STUDIES OF GALACTIC CHEMICAL EVOLUTION ............................................ 241 REFERENCES .............................................................................................................. 278 7 LIST OF FIGURES Figure 2.1. Atmospheric Transmission Plot .................................................................... 13 Figure 2.2. LO Source and Phase Lock Loop for Arizona Radio Observatory ............... 15 Figure 3.1. Energy Level Diagram for CN (X 2Σ+) ......................................................... 19 Figure 3.2. 12CN and 13CN Observations Towards CRL 2688 ........................................ 20 Figure 3.3. Sample Spectra of CN N=2→1 Towards Y CVn .......................................... 21 Figure 3.4. Modeled Line Profiles of CN ........................................................................ 25 Figure 3.5. 12C/13C Circumstellar Ratios vs. C/O ............................................................ 27 Figure 3.6. Detection of HCO+ Towards VY CMa ......................................................... 30 Figure 3.7. CCH Observed Towards Three Evolved Planetary Nebulae ........................ 34 Figure 4.1. Galactic Gradient of 12C/13C as a Function of Distance to the Galactic Center ............................................................................................................ 38 Figure 4.2. H2CO, CN, and CO Chemical Network in Molecular Clouds ...................... 39 Figure 4.3. Sample Spectra of CN N=2→1 in Molecular Clouds ................................... 40 Figure 4.4. Observed Self-Absorption Profile Towards W31 ......................................... 41 Figure 4.5. Rotational Diagram of 12CN in Orion Bar ..................................................... 42 Figure 5.1. Spectra of H2CO with Second Velocity Component in T7 LINEAR ........... 48 Figure 5.2. CH3CN Measured Towards Hale-Bopp ........................................................ 49 8 LIST OF TABLES Table 1. Frequencies and Relative Intensities of CN ....................................................... 24 Table 2. 12C/13C Ratios Measured Towards Circumstellar Envelopes ............................ 29 Table 3. List