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Probing the Trojan-Hilda-KBO Connection: An Empirical Test of Dynamical Instability Models of Solar System Evolution


Wong, Ian Yu (2018) Probing the Trojan-Hilda-KBO Connection: An Empirical Test of Dynamical Instability Models of Solar System Evolution. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9B856BX.


In recent decades, the paradigm of solar system formation has undergone radical change. Many current models posit that a significant reorganization of the outer Solar System occurred after the end of planet formation. Specifically, it is hypothesized that Jupiter and Saturn crossed a mutual mean motion resonance, leading to a chaotic expansion of the ice giants' orbits that disrupted the large population of planetesimals situated further out. While the majority of these bodies were ejected from the Solar System, a fraction of them were retained as the present-day Kuiper Belt, while others were scattered inward and captured into resonances with Jupiter to become the Trojans and Hildas. These dynamical instability models invariably predict that the Trojans, Hildas, and Kuiper Belt objects (KBOs) were sourced from the same primordial body of outer solar system planetesimals. Therefore, a comparative exploration of these minor body populations serves as one of the definitive observational tests of our present understanding of solar system evolution. Over the past four-and-a-half years, I have carried out a diverse series of systematic studies aimed at synthesizing a detailed picture of Trojan, Hildas, and KBOs. By combining novel analyses of archival data with new photometric surveys, I have derived the first debiased color distributions of Trojans and KBOs and expanded our knowledge of their respective size distributions. In addition, I have explored the peculiar color bimodality attested in the all three asteroid populations, which indicates the presence of two sub-populations. Utilizing the full body of observations, I have formulated the first self-consistent hypothesis outlining the formation, composition, and dynamical/chemical evolution of the primordial outer solar system planetesimals, with special attention given to explaining the color bimodality, size distribution shapes, and collisional families. My results lay the groundwork for future studies with next-generation instruments and ultimately, the Trojan flyby mission Lucy.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Planetary Science; Asteroids; Solar System
Degree Grantor:California Institute of Technology
Division:Geological and Planetary Sciences
Major Option:Planetary Sciences
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Brown, Michael E.
Group:Astronomy Department
Thesis Committee:
  • Knutson, Heather A. (chair)
  • Brown, Michael E.
  • Batygin, Konstantin
  • Blake, Geoffrey A.
  • Ehlmann, Bethany L.
Defense Date:20 February 2018
Non-Caltech Author Email:ianyuwong666 (AT)
Record Number:CaltechTHESIS:03012018-170927159
Persistent URL:
Related URLs:
URLURL TypeDescription adapted for Chapter 2. adapted for Chapter 3. adapted for Chapter 4. adapted for Chapter 5. adapted for Chapter 6. adapted for Chapter 7.
Wong, Ian Yu0000-0001-9665-8429
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10746
Deposited By: Ian Wong
Deposited On:13 Mar 2018 17:10
Last Modified:02 Dec 2022 19:48

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