A search for transit timing variations and orbital decay in WASP-46b

Abstract

We present 12 new transit observations of the exoplanet WASP-46b obtained with the 1.54-m telescope at Estación Astrofísica de Bosque Alegre (EABA, Argentina) and the 0.40-m Horacio Ghielmetti and 2.15-m Jorge Sahade telescopes at Complejo Astronómico El Leoncito (CASLEO, Argentina). We analyse them together with 37 light curves from the literature to re-determine the physical parameters and search for additional planets via transit timing variations (TTVs). We consider the 31 transits with uncertainties in their mid-transit times ($e_{{\mathrm{T}}_0}$) $<$ 1 minute, to perform the first homogeneous study of TTVs for the system, finding a dispersion of $\sigma =1.66$ minutes over a 6 year baseline. Since no periodic variations are found, our interpretation for this relatively high value of $\sigma$ is that the stellar activity could be affecting the measured mid-transit times. This value of dispersion allows us to rule out the presence of additional bodies with masses larger than 2.3, 4.6, 7, and 9.3 $M_{⨁}$ at the first-order mean-motion resonances 2:1, 3:2, 4:3, and 5:4 with the transiting planet, respectively. Despite the 6 year baseline and a typical light curve precision of $2\times 10^{-3}$, we find that we cannot significantly demonstrate a slow decrease of the orbital period of WASP-46b. We place a lower limit of Q${}_{\star }$ > $7\times 10^3$ on the tidal quality factor and determine that an additional 6 year baseline is required to rule out Q${}_{\star }$ < $10^5$.

Accepted MNRAS, 16 pages, 10 Figures, 8 Tables

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Cited by in corpus (1)

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