Evidence of Long-Term Period Variations in the Exoplanet Transit Database (ETD)

Hot Jupiters (HJs) are gas giant planets that orbit their host stars with periods less than about 12 days. The proximity of HJs to their host stars leads to tidal interactions that can affect their long-term orbital evolution. Specifically, many HJ orbits could be shrinking gradually over time due to the transfer of angular momentum from the planet to the host star, potentially leading to planetary engulfment (Levrard et al., ApJ, 692; Matsumura et al. 2010, ApJ, 725). Careful observations of planetary transit centres over decade timescales should be sufficient to reveal direct evidence of orbital decay, appearing as a quadratic timing variation. Though many systems of interest have been suggested, only WASP-12 b has been confirmed to be spiraling into its host star (Patra et al., 2017, AJ, 154). In this work, we analyze the wealth of citizen scientist observations in the Exoplanet Transit Database (ETD) to demonstrate that such observations can be used to identify HJ systems that are strong candidates for exhibiting observable orbital evolution.