A New Transiting Planet Search Applied to Kepler and K2: Discovery of Hundreds of Planet Candidates, Eclipsing Binary Stars, and a Self-lensing Binary System
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Since the launch of the Kepler telescope in 2009, the transit method has become the most common way to discover exoplanets. Several groups have created planet search pipelines for both the original Kepler mission and its successor K2. While well designed to find the majority of exoplanets, certain classes of exoplanets are more likely to be overlooked by most planet searches: notably systems displaying three or fewer transits or those with transit timing variations. I have developed a comprehensive planet search technique that is capable of detecting most transiting exoplanets, including the ones commonly missed by other searches. In this thesis I present my transiting planet search, QATS, and I apply it to the first nine campaigns of K2. I have found over 700 planet candidates, including high multiplicity systems with five or six planets. I compare my results to those of other groups and show I am sensitive to planets at all orbital periods, including single transits. I put my results into the context of the wider exoplanet sample, and I show how planets from K2 can answer some questions created by the Kepler planets. Finally, I demonstrate the flexibility of my planet search technique by presenting a fortuitous discovery: the first self-lensing binary star system. What at first appeared to be a reverse transit --- the star getting brighter when a planet passed in front --- is instead a white dwarf in a binary star system whose light gravitationally lenses its companion every orbit. The methods developed in this thesis will be useful for any future transit searches as well, most notably the new TESS mission. With observation sectors of just 27 days, QATS's ability to detect single transits can dramatically extend TESS's sensitivity to planets in more distant orbits; on the other end, QATS's transit timing variation detection will help find planets in the continuous viewing zone, or perhaps planets in an extended mission.
- Astronomy