A hot Uranus transiting the nearby M dwarf GJ 3470
1 UJF-Grenoble 1 / CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG), UMR 5274, 38041 Grenoble, France
2 Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Août 17, Bât. B5C, 4000 Liège, Belgium
3 Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland
4 Institut d’Astrophysique de Paris, CNRS, Université Pierre et Marie Curie, 98bis Bd Arago, 75014 Paris, France
5 Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
6 Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
7 Astrophysics Research Centre, School of Mathematics & Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK
Received: 17 May 2012
Accepted: 23 June 2012
We report on the discovery of GJ 3470 b, a transiting hot Uranus of mass mp = 14.0 ± 1.8 M⊕, radius Rp = 4.2 ± 0.6 R⊕ and period P = 3.3371 ± 0.0002 day. Its host star is a nearby (d = 25.2 ± 2.9 pc) M1.5 dwarf of mass M⋆ = 0.54 ± 0.07 M⊙ and radius R⋆ = 0.50 ± 0.06 R⊙. The detection was made during a radial-velocity campaign with Harps that focused on the search for short-period planets orbiting M dwarfs. Once the planet was discovered and the transit-search window narrowed to about 10% of an orbital period, a photometric search started with Trappist and quickly detected the ingress of the planet. Additional observations with Trappist, EulerCam and Nites definitely confirmed the transiting nature of GJ 3470b and allowed the determination of its true mass and radius. The star’s visible or infrared brightness (Vmag = 12.3, Kmag = 8.0), together with a large eclipse depth D = 0.57 ± 0.05%, ranks GJ 3470 b among the most suitable planets for follow-up characterizations.
Key words: techniques: radial velocities / techniques: photometric / planetary systems / stars: late-type / stars: individual: GJ 3470
Based on observations made with the HARPS instrument on the ESO 3.6 m telescope under the program IDs 183.C-0437 at Cerro La Silla (Chile).
Our radial-velocity and photometric time series are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (22.214.171.124) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/546/A27
© ESO, 2012