SOPHIE velocimetry of Kepler transit candidates

XIX. The transiting temperate giant planet KOI-3680b

¹ Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis Boulevard Arago, 75014 Paris, France
e-mail: hebrard@iap.fr
² Observatoire de Haute-Provence, CNRS, Université d’Aix-Marseille, 04870 Saint-Michel-l’Observatoire, France
³ INAF, Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025, Pino Torinese, Italy
⁴ CONICET, Instituto de Astronomía y Física del Espacio (IAFE), Universidad de Buenos Aires, Buenos Aires, Argentina
⁵ CNRS, CNES, Laboratoire d’Astrophysique de Marseille, Aix Marseille Université, 13388 Marseille, France
⁶ Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
⁷ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua Campo Alegre, 4169-007 Porto, Portugal
⁸ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
⁹ Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
¹⁰ INAF, Osservatorio Astrofisico di Catania, Via S. Sofia, 78, 95123 Catania, Italy
¹¹ Université Côte d’Azur, OCA, Lagrange CNRS, 06304 Nice, France
¹² Canada France Hawaii Telescope Corporation, Kamuela, HI 96743, USA
¹³ Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
¹⁴ Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK

Received: 27 September 2018
Accepted: 19 November 2018

Abstract

Whereas thousands of transiting giant exoplanets are known today, only a few are well characterized with long orbital periods. Here we present KOI-3680b, a new planet in this category. First identified by the Kepler team as a promising candidate from the photometry of the Kepler spacecraft, we establish here its planetary nature from the radial velocity follow-up secured over 2 yr with the SOPHIE spectrograph at Observatoire de Haute-Provence, France. The combined analysis of the whole dataset allows us to fully characterize this new planetary system. KOI-3680b has an orbital period of 141.2417 ± 0.0001 days, a mass of 1.93 ± 0.20 M_Jup, and a radius of 0.99 ± 0.07 R_Jup. It exhibits a highly eccentric orbit (e = 0.50 ± 0.03) around an early G dwarf. KOI-3680b is the transiting giant planet with the longest period characterized so far around a single star; it offers opportunities to extend studies which were mainly devoted to exoplanets close to their host stars, and to compare both exoplanet populations.