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

J. Southworth, A. J. Barker, T. C. Hinse, Y. Jongen, M. Dominik, U. G. Jørgensen, P. Longa-Peña, S. Sajadian, C. Snodgrass, J. Tregloan-Reed, N. Bach-Møller, M. Bonavita, V. Bozza, M. J. Burgdorf, R. Figuera Jaimes, C. Helling, J. A. Hitchcock, M. Hundertmark, E. Khalouei, H. Korhonen, L. Mancini, N. Peixinho, S. Rahvar, M. Rabus, J. Skottfelt, P. Spyratos

HATS-18 b is a transiting planet with a large mass and a short orbital period, and is one of the best candidates for the detection of orbital decay induced by tidal effects. We present extensive photometry of HATS-18 from which we measure 27 times of mid-transit. Two further transit times were measured from data from the Transiting Exoplanet Survey Satellite (TESS) and three more taken from the literature. The transit timings were fitted with linear and quadratic ephemerides and an upper limit on orbital decay was determined. This corresponds to a lower limit on the modified stellar tidal quality factor of Q>105.11±0.04⁠. This is at the cusp of constraining the presence of enhanced tidal dissipation due to internal gravity waves. We also refine the measured physical properties of the HATS-18 system, place upper limits on the masses of third bodies, and compare the relative performance of TESS and the 1.54 m Danish Telescope in measuring transit times for this system.

stars: fundamental parameters, stars: individual: HATS-18, planetary systems

Monthly Notices of the Royal Astronomical Society
Volume 515, Issue 3, Page 3212
2022 September

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia