ABSTRACT
In this project (A Multi-Wavelength View of M17 Massive Star-Forming Region), efforts were made to determine the distributions of polycyclic aromatic hydrocarbons (PAHs) within the M17 region. We find that PAHs are destroyed over a short distance or edge of the HII region. This PAH destruction edge can be located easily using Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) band-ratio images. We try to find out the relative roles of extreme ultraviolet (EUV) and X-ray photons in the destruction of PAHs concluding that X-rays are not an important PAH destruction mechanism in M17 or by extension, in any other Galactic HII region. The result gotten supports the hypothesis that PAHs are destroyed by EUV photons within HII regions. PAHs dominate the mid-IR emission in the neutral Photo-dissociation Region (PDR) beyond the ionized gas.
TABLE OF CONTENTS
TITLE PAGE I
APPROVAL PAGE II
DEDICATION III
ACKNOWLEDGEMENT IV
TABLE OF CONTENTS V
ABSTRACT VI
CHAPTER ONE
INTRODUCTION 1
1.1 BACKGROUND OF STUDY 1
1.1.1 PURPOSE OF STUDY 5
1.1.2 AIM OF THE PARAMETER INVESTIGATED 6
1.2 SPECTRAL CLASSIFICATION OF STARS 6
1.2.1 MAIN CLASSIFICATION 7
1.2.2 SUB-CLASSIFICATION 8
1.2.3 HERZSPRUNG-RUSSELL DIAGRAM (H-R DIAGRAM) 9
1.2.3.1 THE MAIN SEQUENCE 9
1.3 THE GEOMETRY OF M17 11
CHAPTER TWO
LITERATURE REVIEW 15
2.1 MORPHOLOGY OF M17 15
2.2 THE DIFFUSE EMISSION 17
2.3 GLIMPSE AND 2MASS 20
2.4 MID-COURSE SPACE EXPERIMENT (MSX) 21
CHAPTER THREE
DATA ANALYSIS AND RESULTS 23
3.1 SOURCE OF DATA 23
CHAPTER FOUR
DISCUSSION AND CONCLUSION 26
4.1 PAH EMISSION 26
4.2 PAH DESTRUCTION BY EUV AND X-RAY PHOTONS 27
4.3 CONCLUSION 31
REFERNCES 33