Refined Ephemeris for Four Hot Jupiters using Ground-Based and TESS Observations

Abstract

Transit Timing Variation (TTV) is a powerful method to study the dynamics of multiple transiting planetary systems. We examined the TTV of four planetary systems: WASP-12b, WASP-33b, WASP-36b, and WASP-46b. The purpose of this work is to refine the reference ephemeris of these four systems and to draw inferences on any apparent variability of the transits' periodicity. We used the light curves of these systems from the Transiting light Exoplanet Survey Satellite (TESS) observations and some ground-based telescopes. We modeled these light curves to measure the transit times using Exofast. We plotted their TTV diagrams built from our obtained midtransit times and those available in the literature. Our MCMC analysis of these timings enabled us to refined the transit ephemeris of the four systems. We found an apparent variation of the orbital period, 𝑝̇= −24 ± 2 𝑚𝑠 𝑦𝑟 for WASP-12b and 𝑄 * = (2.16 ± 0.35) × 10 for the tidal quality parameter of its host star. We realized that the orbital period is increasing in the WASP-46b system, so its star magnetic activity is a stronger model than orbital decay for period variation of this system. We obtained ∆𝑃 = 7.37 ± 8.64 𝑚𝑠 during 10 years for WASP-36b; It indicates that orbital decay may be present in this system. But since there is no obvious quadratic trend in its TTV diagram, variations are likely due to wrong linear ephemeris that increased over 10 years.