Non-Sinusoidal Transit Timing Variations for the Exoplanet HAT-P-12b

TL;DR

This study analyzes over a decade of transit data for exoplanet HAT-P-12b, revealing potential non-sinusoidal transit timing variations that may indicate an additional unseen planet.

Contribution

It introduces a comprehensive long-term dataset and suggests a non-sinusoidal TTV pattern possibly caused by another non-transiting exoplanet, advancing understanding of this system.

Findings

Large TTV residuals indicating deviations from simple models

Detection of a non-sinusoidal TTV pattern

Possible presence of an additional non-transiting exoplanet

Abstract

Considering the importance of investigating the transit timing variations (TTVs) of transiting exoplanets, we present a follow-up study of HAT-P-12b. We include six new light curves observed between 2011 and 2015 from three different observatories, in association with 25 light curves taken from the published literature. The sample of the data used, thus covers a time span of about 10.2 years with a large coverage of epochs (1160) for the transiting events of the exoplanet HAT-P-12b. The light curves are used to determine the orbital parameters and conduct an investigation of possible transit timing variations. The new linear ephemeris shows a large value of reduced chi-square = 7.93, and the sinusoidal fitting using the prominent frequency coming from a periodogram shows a reduced chi-square around 4. Based on these values and the corresponding O-C diagrams, we suspect the presence of a possible non-sinusoidal TTV in this planetary system. Finally, we find that a scenario with an additional non-transiting exoplanet could explain this TTV with an even smaller reduced chi-square value of around 2.