Searching for orbital decay in southern stars with giant transiting planets: the case of WASP-46

In this contribution we present preliminary results of the photometric follow-up of the star WASP-46, which has a short-period giant-transiting planet (1.43 days). We observed 10 new transits of this exoplanet between July 2012 and September 2015 with the 1.54-m telescope at Estacion Astrofisica de Bosque Alegre (EABA, Argentina) and the 0.40-m Horacio Ghielmetti telescope at Complejo Astronomico El Leoncito (CASLEO, Argentina). Furthermore, we collect other 31 transits from the literature and re-determine the photometric parameters of the system from the complete, most precise light curves of the sample. On the other hand, we also fit the 25 transits with uncertainties in their mid-transit times lower than 1 minute, with a linear and a quadratic model to assess the possibility of a systematic decreasing in the orbital period. This analysis reveals that a linear ephemeris is the best representation of the data, and shows no hint of orbital decay in the system, at least during 4 years of observations.

The results suggest that the globular cluster formation process has not been completely stochastic but, rather, included a significant fraction of globulars that formed in a synchronized way and over supra-galactic spatial scales. A tentative approach indicates that the putative events that enhanced globular cluster formation took place during a time lapse of years and in a range of redshifts between 2 and 4.