Searching for Planets and Moons Using Gravitational Dynamics

The search for planets around stars other than our Sun, known as "exoplanets", has made use of a variety of different methods. Some methods look for the planet itself through direct imaging. Other techniques search for the signature of planets in the light from its parent star. Such indicators of a planet include the dimming of the star as the planet passes in front of it (the Transit method) or the discrepancy in events that occur from the influence of unseen planets (the Transit Timing Variation method). These techniques allow the discovery of worlds not otherwise visible to telescopes, through the orbital dynamics of known worlds. This work pursues the premise of detecting hidden celestial bodies through their effect upon visible ones. In the first chapter, I examine the usefulness of the Canadian space telescope, the Near Earth Object Surveillance Satellite (NEOSSat), as a tool for exoplanetary science. I performe follow-up observations of several targets from the Transiting Exoplanet Survey Satellite (TESS). These observations improve the orbital ephemerides and baselines for these ex- oplanets, as well as demonstrate the capabilities of NEOSSat as a tool for exoplanetary science. In the second chapter, I examine whether moons around exoplanets ("exomoons") could be detected via the transit timing variations they exert upon their planet. Exomoons are exceptionally difficult to detect via transits, but an exomoon could reveal itself through the gravitational effect it has upon on its parent planet. Thirteen Kepler systems are explored to determine whether this hypothesis could hold. The observed behaviour of eight systems is consistent with the presence of an exomoon, though this is insufficient to confirm the existence of a moon. In the third chapter, I examine the debris disk around HD 181327. It shows a significant asymmetry in its surface brightness profile when viewed in visible light. By performing N-body simulations, I find that a 2-5 Jupiter-mass planet on a circular orbit at 62 au could produce and maintain a similar feature to that observed. Gravity is the universal architect of planetary systems. The existence of a hidden celestial body can be betrayed by its gravitational influence upon another. In this thesis, I explore new ways of using gravity in this vein.

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