Revisiting TrES-5 b: departure from a linear ephemeris instead of short-period transit timing variation

Abstract

Aims. The orbital motion of the transiting hot Jupiter TrES-5 b was reported to be perturbed by a planetary companion on a nearby orbit. Such compact systems do not frequently occur in nature, and investigating their orbital architecture could shed some light on the formation processes of hot Jupiters. Methods. We acquired 15 new precise photometric time-series for 12 transits of TrES-5 b between June 2019 and October 2020 using 0.9–2.0 m telescopes. The method of precise transit timing was employed to verify the deviation of the planet from the Keplerian motion. Results. Although our results show no detectable short-time variation in the orbital period of TrES-5 b and the existence of the additional nearby planet is not confirmed, the new transits were observed about two minutes earlier than expected. We conclude that the orbital period of the planet could vary on a long timescale. We found that the most likely explanation of the observations is the line-of-sight acceleration of the system’s barycentre caused by the orbital motion induced by a massive, wide-orbiting companion.

Revisiting the Transit Timing Variations in the TrES-3 and Qatar-1 Systems with TESS Data

“…As the obtained value of k p = 1.95 ± 0.26 for Qatar-1b is an unphysical value with a large uncertainty, it is difficult to infer the interior density profile of this hot Jupiter. This indicates a nondetection of apsidal precession using the available timing data of Qatar-1b (Maciejewski et al 2021). To confirm this, future follow-up observations of transits and occultations will be needed.…”

“…We thus explored this possibility for the TrES-3 and Qatar-1 systems. To do so, we followed Maciejewski et al (2021) and fitted the following orbital decay model to the timing data of both the hot Jupiters:…”

“…As the timescales for tidal circularization are much smaller than the ages of the systems, the presence of an orbital eccentricity is inconsistent with tidal theory. If apsidal precession is taking place in these systems, there must be some mechanism that can excite and maintain a nonzero eccentricity (see Bouma et al 2019;Maciejewski et al 2021). In this context, Ragozzine & Wolf (2009) showed that the interiors of very hot Jupiters could be a dominant source for apsidal precession.…”

“…Acceleration toward the observer causes a decreasing period, whereas an increasing period corresponds to acceleration away from the observer. If the centers of mass of the TrES-3 and Qatar-1 systems were really accelerating away from us with an amplitude  v RV , then the observed  P q of their hot Jupiters would be related to  v RV by the following equation of Maciejewski et al (2021):…”

A search for transit timing variations in the HATS-18 planetary system

“…WASP-4 is also known to have a decreasing orbital period (Bouma et al 2019;Southworth et al 2019) but the origin of this is not yet settled (Baluev et al 2020;Bouma et al 2020;Turner et al 2022). TTVs can arise due to the light-time effect caused by longperiod companions in a system, as has been found for TrES-5 (Maciejewski et al 2021), WASP-148 (Maciejewski et al 2020) and HAT-P-26 (von Essen et al 2019). TTVs can also be caused by apsidal precession (Patra et al 2017), starspots (Watson & Dhillon 2004;Oshagh et al 2013), the Applegate mechanism (Applegate 1992;Watson & Marsh 2010) and gravitational perturbations in multi-planetary systems (e.g.…”