WASP-103 b: a new planet at the edge of tidal disruption ^⋆

¹ Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, Sart Tilman, 4000 Liège 1, Belgium
e-mail: michael.gillon@ulg.ac.be
² Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
³ SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
⁴ Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
⁵ Department of Physics, University of Warwick, Coventry CV4 7AL, UK
⁶ Cavendish Laboratory, Department of Physics, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
⁷ N. Copernicus Astronomical Centre, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland
⁸ Department of Physics and Kavli Institute for Astrophysics & Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Received: 8 November 2013
Accepted: 9 January 2014

Abstract

We report the discovery of WASP-103 b, a new ultra-short-period planet (P = 22.2 h) transiting a 12.1 V-magnitude F8-type main-sequence star (1.22 ± 0.04 M_⊙, 1.44_-0.03^+0.05 R_⊙, T_eff = 6110 ± 160 K). WASP-103 b is significantly more massive (1.49 ± 0.09 M_Jup) and larger (1.53_-0.07^+0.05 R_Jup) than Jupiter. Its large size and extreme irradiation (~ 9 × 10⁹ erg s^-1 cm^-2) make it an exquisite target for a thorough atmospheric characterization with existing facilities. Furthermore, its orbital distance is less than 20% larger than its Roche radius, meaning that it might be significantly distorted by tides and might experience mass loss through Roche-lobe overflow. It thus represents a new key object for understanding the last stage of the tidal evolution of hot Jupiters.