Hot Jupiters with relatives: discovery of additional planets in orbit around WASP-41 and WASP-47^⋆,⋆⋆

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 Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
⁵ SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife, KY16 9SS, UK
⁶ Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août, 17, Bat. B5C, 19C 4000 Liège 1, Belgium
⁷ Las Cumbres Observatory Global Telescope Network, 6740 Cortona Dr. Suite 102, Goleta, CA 93117, USA
⁸ Departamento de Astronomía, Universidad de Chile, Camino El Observatorio 1515, Las Condes, Santiago, Chile
⁹ Centre for Planetary Sciences, University of Toronto at Scarborough, 1265 Military Trail, Toronto, ON, M1C 1A4, Canada
¹⁰ Department of Astronomy & Astrophysics, University of Toronto, Toronto, ON, M5S 3H4, Canada

Received: 14 July 2015
Accepted: 30 September 2015

Abstract

We report the discovery of two additional planetary companions to WASP-41 and WASP-47. WASP-41 c is a planet of minimum mass 3.18 ± 0.20 M_Jup and eccentricity 0.29 ± 0.02, and it orbits in 421 ± 2 days. WASP-47 c is a planet of minimum mass 1.24 ± 0.22 M_Jup and eccentricity 0.13 ± 0.10, and it orbits in 572 ± 7 days. Unlike most of the planetary systems that include a hot Jupiter, these two systems with a hot Jupiter have a long-period planet located at only ~1 au from their host star. WASP-41 is a rather young star known to be chromospherically active. To differentiate its magnetic cycle from the radial velocity effect induced by the second planet, we used the emission in the Hα line and find this indicator well suited to detecting the stellar activity pattern and the magnetic cycle. The analysis of the Rossiter-McLaughlin effect induced by WASP-41 b suggests that the planet could be misaligned, though an aligned orbit cannot be excluded. WASP-47 has recently been found to host two additional transiting super Earths. With such an unprecedented architecture, the WASP-47 system will be very important for understanding planetary migration.