WASP-12 b – an exoplanet falling onto its host star?

Gracjan Maciejewski

With the orbital period as short as 26 hours, the transiting planet WASP-12 b belongs to a group of planets of the tightest orbits. We detected the apparent shortening of its orbital period that could be caused by orbital decay or apsidal precession due to tidal interactions. The reanalysis of available data allowed us to identify an alternative scenario that explains the departure of the transit timing from a linear ephemeris. We found a solution with an additional planet, whose mass is about 17 Earth masses and the orbital period is 3.2 d. We found that this planet can perturb the orbital motion of WASP-12 b that manifests as the apparent orbital decay. Our dynamical model shows that the planet is likely to transit the host star. We plan to acquire precise photometric time series for WASP-12 in the 2017/2018 observing season to confirm the existence of the postulated planet and to determine its parameters.

Proceedings of the Polish Astronomical Society, vol. 7, 113-117 (2018)

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