WASP-94 A and B planets: hot-Jupiter cousins in a twin-star system^⋆

¹ Observatoire Astronomique de l’Université de Genève, Chemin des Maillettes 51, 1290 Sauverny, Switzerland
e-mail: marion.neveu@unige.ch
² Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, UK
³ Astrophysics Group, Keele University, Staffordshire, ST5 5BG, UK
⁴ SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
⁵ Institut d’Astrophysique et de Géophysique, Université de Liège,17, Allée du 6 Août, Bat. B5C, 1290 Liège, Belgium
⁶ Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
⁷ N. Copernicus Astronomical Centre, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland
⁸ Kavli Institute for Astrophysics & Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

Received: 4 August 2014
Accepted: 18 September 2014

Abstract

We report the discovery of two hot-Jupiter planets, each orbiting one of the stars of a wide binary system. WASP-94A (2MASS 20550794–3408079) is an F8 type star hosting a transiting planet with a radius of 1.72 ± 0.06 R_Jup, a mass of 0.452 ± 0.034 M_Jup, and an orbital period of 3.95 days. The Rossiter-McLaughlin effect is clearly detected, and the measured projected spin-orbit angle indicates that the planet occupies a retrograde orbit. WASP-94B (2MASS 20550915–3408078) is an F9 stellar companion at an angular separation of 15′′ (projected separation 2700 au), hosting a gas giant with a minimum mass of 0.618 ± 0.028 M_Jup with a period of 2.008 days, detected by Doppler measurements. The orbital planes of the two planets are inclined relative to each other, indicating that at least one of them is inclined relative to the plane of the stellar binary. These hot Jupiters in a binary system bring new insights into the formation of close-in giant planets and the role of stellar multiplicity.