WASP-64 b and WASP-72 b: two new transiting highly irradiated giant planets^⋆

¹ Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 août 17, Sart Tilman, Liège 1, Belgium
e-mail: michael.gillon@ulg.ac.be
² Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
³ 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 Department of Physics and Astronomy, University of Leicester, Leicester, LE1 7RH, UK

Received: 15 October 2012
Accepted: 11 February 2013

Abstract

We report the discovery by the WASP transit survey of two new highly irradiated giant planets. WASP-64 b is slightly more massive (1.271 ± 0.068 M_Jup) and larger (1.271 ± 0.039 R_Jup) than Jupiter, and is in very-short (a = 0.02648 ± 0.00024 AU, P = 1.5732918 ± 0.0000015 days) circular orbit around a V = 12.3 G7-type dwarf (1.004 ± 0.028 M_⊙, 1.058 ± 0.025 R_⊙, T_eff = 5500 ± 150 K). Its size is typical of hot Jupiters with similar masses. WASP-72 b has also a mass a bit higher than Jupiter’s (1.461_-0.056^+0.059 M_Jup) and orbits very close (0.03708 ± 0.00050 AU, P = 2.2167421 ± 0.0000081 days) to a bright (V = 9.6) and moderately evolved F7-type star (1.386 ± 0.055 M_⊙, 1.98 ± 0.24 R_⊙, T_eff = 6250 ± 100 K). Despite its extreme irradiation (~5.5 × 10⁹ erg s^-1 cm^-2), WASP-72 b has a moderate size (1.27 ± 0.20 R_Jup) that could suggest a significant enrichment in heavy elements. Nevertheless, the errors on its physical parameters are still too high to draw any strong inference on its internal structure or its possible peculiarity.