Revisiting the Orbital Dynamics of the Hot Jupiter WASP-12b with New Transit Times

Abstract: In this study, we examine the transit timing variations (TTVs) of the extensively studied hot Jupiter WASP-12b using a comprehensive dataset of 391 transit light curves. The dataset includes 7 new photometric observations obtained with the 1.3 m Devasthal Fast Optical Telescope, the 0.61 m VASISTHA telescope, and the 0.3 m AG Optical IDK telescope, along with 119 light curves from the Transiting Exoplanet Survey Satellite (TESS), 97 from the Exoplanet Transit Database (ETD), 34 from the ExoClock Project, and 134 from previously published sources. To ensure homogeneity and precision, we modeled all 391 light curves and determined their mid-transit times. A detailed transit timing analysis revealed a significant orbital decay rate of $-30.31 \, \mathrm{ms \, yr^{-1}}$, corresponding to a stellar tidal quality factor of $Q'_\star = 1.61 \times 10^{5}$, thereby confirming that the orbit of WASP-12b is indeed decaying rapidly. Furthermore, the computation of model selection metrics ($\chi^2_r$, BIC, AIC) favors orbital decay as the most likely explanation. However, the presence of an eccentricity above the threshold value allows apsidal precession to remain a viable alternative. We also derived a planetary Love number of $k_p = 0.66 \pm 0.28$, consistent with Jupiter's value, suggesting a similar internal density distribution. Therefore, while orbital decay is strongly supported, apsidal precession cannot be ruled out as another contributing effect, highlighting the necessity of continued high-precision monitoring to resolve the system's orbital evolution.