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The leftovers of planet formation : small body populations of our solar system and exoplanet systems Lawler, Samantha


The small body populations within a planetary system give information about the planet formation and migration history of the system. In our Solar System, we study these bodies (asteroids, comets, and trans-Neptunian objects), by directly observing them in reflected light. In other solar systems, dust traces the position of the planetesimal belts that produce it, and is observed as an excess above the stellar flux in the infrared. The dust is visible and not the planetesimals because of the much greater cross-sectional surface area of a swarm of dust particles. In this thesis, both leftover large planetesimals in our Solar System and dust around other stars are investigated. Data from the Canada-France Ecliptic Plane Survey (CFEPS) are used to measure the absolute populations of trans Neptunian objects (TNOs) in mean-motion resonances with Neptune, as well as constrain the internal orbital element distributions. Detection biases play a critical role because phase relationships with Neptune make object discovery more likely at certain longitudes. The plutinos (objects in the 3:2 resonance) are given particular attention because the presence of the secular Kozai resonance within the mean-motion resonance causes different detection biases that need to be accounted for to properly debias surveys that include detections of plutinos. Because the TNOs that are trapped in mean-motion resonances with Neptune were likely emplaced there during planet migration late in the giant planet formation process, the structure within and relative populations of the resonances should be a diagnostic of the timescale and method of giant planet migration. Exoplanet systems that host several rocky planets are those that did not experience giant planet migration, and thus are likely to host planetesimal belts which should be detectable as debris disks. The Kepler Mission has detected a host of such systems, and we use data from the Wide-field Infrared Survey Explorer (WISE) Mission to search for debris disks around these stars. Though we tentatively detect more excesses toward these stars than would be expected, contamination from warm dust in the Milky Way Galaxy makes detection unreliable for these systems, and will have to await future infrared space telescopes.

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