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The GAPS programme with HARPS-N at TNG
VI. The curious case of TrES-4b

A. Sozzetti, A. S. Bonomo, K. Biazzo, L. Mancini, M. Damasso, S. Desidera, R. Gratton, A. F. Lanza, E. Poretti, M. Rainer, L. Malavolta, L. Affer, M. Barbieri, L. Bedin, C. Boccato, M. Bonavita, F. Borsa, S. Ciceri, R. Claudi, D. Gandolfi, P. Giacobbe, T. Henning, C. Knapic, D. W. Latham, G. Lodato, A. Maggio, J. Maldonado, F. Marzari, A. F. Martinez Fiorenziano, G. Micela, E. Molinari, C. Mordasini, V. Nascimbeni, I. Pagano, M. Pedani, F. Pepe, G. Piotto, N. C. Santos, G. Scandariato, E. Shkolnik, J. Southworth

We update the TrES-4 system parameters using high-precision HARPS-N radial-velocity measurements and new photometric light curves. A combined spectroscopic and photometric analysis allows us to determine a spectroscopic orbit with a semi-amplitude K = 51 ± 3 m s-1. The derived mass of TrES-4b is found to be Mp = 0.49 ± 0.04 MJup, significantly lower than previously reported. Combined with the large radius (Rp = 1.84-0.09+0.08 RJup) inferred from our analysis, TrES-4b becomes the transiting hot Jupiter with the second-lowest density known. We discuss several scenarios to explain the puzzling discrepancy in the mass of TrES-4b in the context of the exotic class of highly inflated transiting giant planets.

stars: individual: TrES-4b – planetary systems – techniques: radial velocities – techniques: spectroscopic – techniques: photometric

Astronomy & Astrophysics
Volume 575, Number of pages L15_1
2015 March

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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