Homogeneously derived transit timings for 17 exoplanets and reassessed TTV trends for WASP-12 and WASP-4
Molina, D.; Bretton, M.; Jones, H. R. A.; Fernández-Lajús, E.; Guerra, P.; Nielsen, L. D.; Baştürk, Ö.; Evans, P.; Benni, P.; Kim, T.; Kang, W.; Marchini, A.; Papini, R.; Salvaggio, F.; Hentunen, V. -P.; Shadick, S.; Garlitz, J.; Jongen, Y.; Baluev, R. V.; Di Sisto, R. P.; Sokov, E. N.; Qvam, J. K. T.; Ogmen, Y.; Schneiter, E. M.; Ibrahimov, M. A.; Shaidulin, V. Sh; Sokova, I. A.; Villarreal D'Angelo, C.; Wunsche, A.; PakštienÄ--, E.; Knight, C. R.; Salisbury, M.; Garcia, F.; Esseiva, N.; Karavaev, Yu; Rusov, S.; Karimov, R. G.
Russia, United Kingdom, Switzerland, United States, Argentina, Ireland, Turkey, France, Finland, Canada, South Korea, Lithuania, Norway, New Zealand, Spain, Italy, Chile, Cyprus, Uzbekistan
Abstract
We homogeneously analyse ∼3.2 × 105 photometric measurements for ∼1100 transit light curves belonging to 17 exoplanet hosts. The photometric data cover 16 years (2004-2019) and include amateur and professional observations. Old archival light curves were reprocessed using up-to-date exoplanetary parameters and empirically debiased limb-darkening models. We also derive self-consistent transit and radial-velocity fits for 13 targets. We confirm the non-linear transit timing variation (TTV) trend in the WASP-12 data at a high significance, and with a consistent magnitude. However, Doppler data reveal hints of a radial acceleration of about -7.5 ± 2.2 m s-1 yr-1, indicating the presence of unseen distant companions, and suggesting that roughly 10 per cent of the observed TTV was induced via the light-travel (or Roemer) effect. For WASP-4, a similar TTV trend suspected after the recent TESS observations appears controversial and model dependent. It is not supported by our homogeneous TTV sample, including 10 ground-based EXPANSION light curves obtained in 2018 simultaneously with TESS. Even if the TTV trend itself does exist in WASP-4, its magnitude and tidal nature are uncertain. Doppler data cannot entirely rule out the Roemer effect induced by possible distant companions.