No variations in transit times for Qatar-1 b

TL;DR

This study conducted extensive follow-up observations of Qatar-1 b, finding no evidence of transit timing variations or nearby planetary companions, thus supporting the idea that hot Jupiters typically do not have close-in planetary systems.

Contribution

The paper provides a comprehensive, homogeneous analysis of transit data confirming the absence of TTVs and close companions for Qatar-1 b, refining system parameters with higher precision.

Findings

Transit times are consistent with a linear ephemeris.

No evidence of a close-in planetary companion.

Refined system parameters with improved precision.

Abstract

The transiting hot Jupiter planet Qatar-1 b was presented to exhibit variations in transit times that could be of perturbative nature. A hot Jupiter with a planetary companion on a nearby orbit would constitute an unprecedented planetary configuration, important for theories of formation and evolution of planetary systems. We performed a photometric follow-up campaign to confirm or refute transit timing variations. We extend the baseline of transit observations by acquiring 18 new transit light curves acquired with 0.6-2.0 m telescopes. These photometric time series, together with data available in the literature, were analyzed in a homogenous way to derive reliable transit parameters and their uncertainties. We show that the dataset of transit times is consistent with a linear ephemeris leaving no hint for any periodic variations with a range of 1 min. We find no compelling evidence for the existence of a close-in planetary companion to Qatar-1 b. This finding is in line with a paradigm that hot Jupiters are not components of compact multi-planetary systems. Based on dynamical simulations, we place tighter constraints on a mass of any fictitious nearby planet in the system. Furthermore, new transit light curves allowed us to redetermine system parameters with the precision better than that reported in previous studies. Our values generally agree with previous determinations.