Transit timing variation in exoplanet WASP-3b

TL;DR

This study analyzes transit timing variations of exoplanet WASP-3b to suggest the presence of a potential second planet near a 2:1 resonance, highlighting the need for further observations for confirmation.

Contribution

First detection of periodic transit timing variations in WASP-3b suggesting a possible second planet near a 2:1 resonance.

Findings

Transit timing variations are best explained by a second planet of about 15 Earth masses.

The hypothetical second planet is likely near the 2:1 mean motion resonance.

Additional observations are necessary to confirm the second planet's existence.

Abstract

Photometric follow-ups of transiting exoplanets may lead to discoveries of additional, less massive bodies in extrasolar systems. This is possible by detecting and then analysing variations in transit timing of transiting exoplanets. We present photometric observations gathered in 2009 and 2010 for exoplanet WASP-3b during the dedicated transit-timing-variation campaign. The observed transit timing cannot be explained by a constant period but by a periodic variation in the observations minus calculations diagram. Simplified models assuming the existence of a perturbing planet in the system and reproducing the observed variations of timing residuals were identified by three-body simulations. We found that the configuration with the hypothetical second planet of the mass of about 15 Earth masses, located close to the outer 2:1 mean motion resonance is the most likely scenario reproducing observed transit timing. We emphasize, however, that more observations are required to constrain better the parameters of the hypothetical second planet in WASP-3 system. For final interpretation not only transit timing but also photometric observations of the transit of the predicted second planet and the high precision radial-velocity data are needed.