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

Abstract

We analyze a large number of citizen science data and identify eight hot Jupiter systems that show evidence for deviations from a constant orbital period: HAT-P-19 b, HAT-P-32 b, TrES-1 b, TrES-2 b, TrES-5 b, WASP-4 b, WASP-10 b, and WASP-12 b. The latter system is already well known to exhibit strong evidence for tidal orbital decay and serves as an important control for this study. Several other systems we identify have disputed period drifts in the literature, allowing the results here to serve as an independent analysis. The citizen science data are from the Exoplanet Transit Database (ETD), which is a global project established in 2008 by the Variable Star and Exoplanet Section of the Czech Astronomical Society. With over 400 planets and 12,000 contributed observations spanning 15 yr, the ETD is brimming with potential for studying the long-term orbital evolution of close-in hot Jupiters. We use our results to discuss prioritization of targets for follow-up investigations, which will be necessary to confirm the period drifts and their causes.