The search for orbital decay in hot Jupiters

Abstract

We summarize our results, so far, in the search for orbital decay in exoplanets. Orbital decay is the gradual shrinkage of the planetary orbit due to tidal dissipation. We ranked currently known exoplanetary systems according to the theoretical orbital decay rate and trimmed the list down to 12 best targets. We collected new transit light curves for the targets visible in the northern hemisphere using the 1.2 m telescope at the Fred L. Whipple Observatory, Arizona. For the southern targets, we are currently collaborating with the Las Cumbres Observatory Telescope Network to obtain new transits. We analyzed the timing residuals for each target, seeking evidence for any change in the orbital period. Currently, the best candidate for orbital decay is WASP-12 b with an observed period derivative ... . However, we find that a few other possible models, including apsidal precession, nodal precession and color-dependent transit times, cannot be ruled out completely. Continous monitoring of WASP-12 b is necessary in the future to resolve the current conundrum. The search for orbital decay is still in its infancy for most other targets. However, we aim to produce a few transit times for each target to serve as an "anchor" for when TESS relays back more high quality light curves.