EVIDENCE OF ACCRETION-GENERATED X-RAYS IN THE YOUNG ...

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ACKNOWLEDGMENTS This work would not have been possible if it were not for the e↵orts of many people who have made a major impact in my life, and I would feel it would be a great disrespect if I did not acknowledge the people who have played such an important role in getting me to this point in my career. First and foremost, this dissertation would not exist if it were not for my parents, Cheryl and Bill. Through their loving e↵orts, they have made me what I am today, and I cannot thank them enough for all that they have done for me in my thirty years of life. In addition, I would like to acknowledge my many friends and family members, too numerous to name individually, that have supported me in my endeavors. Iwouldhavetosaythatmyloveofastronomybeganfromaseedthatmypar- ents planted in my mind when I was a young child. They provided me with my first telescope - a small refractor. Though we weren’t able to find much more than the Moon or a few bright stars, this nevertheless fostered my love of astronomy. I remem- ber flipping through the many astronomy books they bought me when I was very young (all of which I still have today) and marveling at the beauty of the universe, wondering if I could be an astronaut someday. Once I was in high school, my love of astronomy and space science accelerated. For Christmas one year, my parents bought me another telescope, this time a 4.5” Newtonian, which was an upgrade from the small refractor that I had received many years before. The first clear night I had it out I was able to view Jupiter and Saturn. I dashed in and brought my parents out to see the two planets I had observed for iii
the first time through a telescope, allowing them to see the two heavenly bodies telescopically for the first time as well. From then on, I continued learning the constellations and star names, researching the many types of objects that I could now view, and staying up late many nights to observe the sky. When I was in college at Austin Peay State University, I began taking physics courses (quickly changing my major from Engineering Technology to Physics once I discovered my true love of physics). I quickly became great friends with the Physics & Astronomy faculty. At this point, I also began participating in the observation nights held for our astronomy classes, operating the 8” Meade LX-90 and 10” Dobsonian telescopes that I had purchased with the remainder of my scholarship funds. I quickly learned that, along with my love of astronomy, I also had a passion for teaching it as well- I now had a career goal in mind. The faculty and sta↵ of the APSU Physics & Astronomy department, namely Drs. Jaime Taylor, Spencer Buckner, Alex King, and Pei Xiong-Skiba, along with Sherry Bagwell, helped me pursue this career. I am greatly indebted to these wonderful people. Once I had received my bachelors in Physics, I was accepted to the Physics graduate program at Vanderbilt University. I was one of six individuals accepted that year to become part of the graduate program that had an emphasis in astronomy. After several years of taking classes and acting as a teaching assistant for several astronomy lectures and many astronomy lab sections, I became a research assistant to Dr. David Weintraub. Through my interaction with David I have not only gained an enormous understanding of young stars and other aspects of my research field but I have also learned how to become a good researcher, gained an understanding of how iv
Page 1 and 2: EVIDENCE OF ACCRETION-GENERATED X-R
Page 3: 4.3.2. Spectral Modeling . . . . .
Page 7 and 8: List of Tables Table Page 1. 2002-2
Page 9 and 10: 19. Correlation Between Changes in
Page 11 and 12: on Earth, nay, the entire solar sys
Page 13 and 14: known as a molecular cloud. These s
Page 15 and 16: internal pressure will be overcome.
Page 17 and 18: With advancements in telescope and
Page 19 and 20: the circumstellar disk, such as the
Page 21 and 22: perturbations or disk instabilities
Page 23 and 24: CHAPTER II ERUPTING YOUNG STARS 2.1
Page 25 and 26: (1997). Once the TTS spectral class
Page 27 and 28: Annu. Rev. Astro. Astrophys. 1996.3
Page 29 and 30: FUors have typical accretion rates
Page 31 and 32: and radiative equilibrium and that
Page 33 and 34: CHAPTER III X-RAY ASTRONOMY: A TOOL
Page 35 and 36: of the X-ray luminosity (LX) totheb
Page 37 and 38: filtered light curves (which had la
Page 39 and 40: 3.1.4 Gleaning Other Information fr
Page 41 and 42: Fig. 9a ~6.4 keV ~6.7 keV Figure 8:
Page 43 and 44: 34 Figure 9: Schematic of the Chand
Page 45 and 46: Figure 10: Schematic of the Chandra
Page 47 and 48: Top View Rowland Circle Grating fac
Page 49 and 50: electrons eventually exits the outp
Page 51 and 52: one to e↵ectively determine the e
Page 53 and 54: pixels or pixel columns. • Parame
Page 55 and 56:
deal of built-in flexibility in how
Page 57 and 58:
accrete most of their mass (Hartman
Page 59 and 60:
4.2 Observations & Data Reduction O
Page 61 and 62:
were grouped into energy bins with
Page 63 and 64:
Since V1647 Ori was imaged with bot
Page 65 and 66:
4.3 Results 4.3.1 Short-Term and Lo
Page 67 and 68:
overall X-ray light curve, the soft
Page 69 and 70:
Count Rate (cts/s) Count Rate (cts/
Page 71 and 72:
Page 73 and 74:
Page 75 and 76:
The highest measured X-ray mean cou
Page 77 and 78:
during short-term variability, howe
Page 79 and 80:
Change in Mean Hardness Ratio 1 0.5
Page 81 and 82:
These results suggest that we can i
Page 83 and 84:
Table 3. Model Fits for 2008-2009 C
Page 85 and 86:
For the CXO observations of V1647 O
Page 87 and 88:
normalized counts s −1 keV −1
Page 89 and 90:
Determining a robust model for the
Page 91 and 92:
April 4 XMM observation (109 eV) an
Page 93 and 94:
s −1 ) Log Observed Flux (ergs cm
Page 95 and 96:
tures of a few million Kelvin (kTX
Page 97 and 98:
2004 March, especially if the large
Page 99 and 100:
and AK =0.5on2004Feburary18,allofwh
Page 101 and 102:
In order to test whether CXO would
Page 103 and 104:
• and X-ray luminosities that are
Page 105 and 106:
With V1647 Ori being observed inten
Page 107 and 108:
level approximately one year after
Page 109 and 110:
of an object in which this process
Page 111 and 112:
eduction. In §3, we discuss the re
Page 113 and 114:
Table 5. Chandra ACIS Observations
Page 115 and 116:
5.3 Results from X-ray Observations
Page 117 and 118:
y an intervening column of hydrogen
Page 119 and 120:
Table 6. Best-Fit Models for EX Lup
Page 121 and 122:
component plasma, subject to a sing
Page 123 and 124:
does require a third, heavily-absor
Page 125 and 126:
5.3.3 The Temporal Evolution of the
Page 127 and 128:
Figure 29 shows the three CXO spect
Page 129 and 130:
From 2008 June to August, the plasm
Page 131 and 132:
June, however, the X-ray flux from
Page 133 and 134:
to test this light curve for possib
Page 135 and 136:
We note that in the above analysis,
Page 137 and 138:
5.5 Discussion & Conclusions The op
Page 139 and 140:
CHAPTER VI DISCUSSION AND CONCLUSIO
Page 141 and 142:
sensitive line diagnostics that wou
Page 143 and 144:
Bell, K. R., Lin, D. N. C., & Ruden
Page 145 and 146:
Hartmann, L. & Kenyon, S. J. 1996,
Page 147 and 148:
Orlando, S., Peres, G., & Reale, F.
Page 149:
Venkat, V. & Anandarao, B. G. 2011,
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