TTVs analysis in Southern Stars: the case of WASP-28

TL;DR

This study analyzes four new and eleven existing transits of exoplanet WASP-28b over three years, finding no evidence of additional planets through TTVs and exploring correlations between transit parameters and noise factors.

Contribution

It provides updated ephemeris and physical parameters for WASP-28b and investigates potential correlations between transit characteristics and observational noise factors.

Findings

No periodic TTVs detected over 3 years.

Weak correlations found between transit depth and noise factors.

WASP-28 is classified as a thin disk star.

Abstract

We present 4 new transit observations of the exoplanet WASP-28b observed between August 2011 and October 2013. Employing another 11 transits available in the literature we compute new ephemeris and redetermine the physical parameters of the star and the exoplanet. Considering 3 yrs of observations, we find no periodic TTVs or long-term variations of the inclination of the orbit, i, or the depth of the transit, k, that could be attributable to the presence of another planetary mass-body in the system. We also study the relations between i and k with different factors that characterize the light-curves. The fits suggest a possible weak correlation between k with the red noise factor, \beta, and the photometric noise rate, PNR, and a weak anticorrelation between i and PNR, although more points are needed to confirm these trends. Finally, the kinematic study suggests that WASP-28 is a thin disk star.