Volume 599, March 2017
|Number of page(s)||10|
|Section||Planets and planetary systems|
|Published online||20 February 2017|
From dense hot Jupiter to low-density Neptune: The discovery of WASP-127b, WASP-136b, and WASP-138b⋆
1 University of Warwick, Department of Physics, Gibbet Hill Road, Coventry, CV4 7AL, UK
2 Astrophysics Group, Keele University, Staffordshire ST5 5BG, UK
3 Institut d’Astrophysique et de Géophysique, Université de Liège, Allée du 6 Aout, 17 Bât. B5C, Liège 1, Belgium
4 Institut d’Astrophysique de Paris, UMR 7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
5 Observatoire de Haute-Provence, Université d’Aix-Marseille & CNRS, 04870 Saint-Michel-l’ Observatoire, France
6 Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria
7 Observatoire de Genève, Université de Genève, 51 Chemin des Maillettes, 1290 Sauverny, Switzerland
8 Max Planck Institute for Astronomy, Koenigstuhl 17, 69117 Heidelberg, Germany
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
11 Institute of Astronomy, Madingley Road, Cambridge, CB3 0HA, UK
12 SUPA, School of Physics and Astronomy, University of St. Andrews, North Haugh, Fife KY16 9SS, UK
13 ARC, School of Mathematics & Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN, UK
14 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
15 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
16 INAF–Osservatorio Astrofisico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
17 Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Penteli, Greece
18 Instituto de Astrofisica de Canarias, via Lactea sn, 38200 La Laguna, Tenerife, Spain
19 Cavendish Laboratory, J J Thomson Avenue, Cambridge, CB3 0HE, UK
Received: 22 July 2016
Accepted: 20 October 2016
We report three newly discovered exoplanets from the SuperWASP survey. WASP-127b is a heavily inflated super-Neptune of mass 0.18±0.02 MJ and radius 1.37±0.04 RJ. This is one of the least massive planets discovered by the WASP project. It orbits a bright host star (Vmag = 10.16) of spectral type G5 with a period of 4.17 days. WASP-127b is a low-density planet that has an extended atmosphere with a scale height of 2500 ± 400 km, making it an ideal candidate for transmission spectroscopy. WASP-136b and WASP-138b are both hot Jupiters with mass and radii of 1.51 ± 0.08 MJ and 1.38 ± 0.16 RJ, and 1.22 ± 0.08 MJ and 1.09 ± 0.05 RJ, respectively. WASP-136b is in a 5.22-day orbit around an F9 subgiant star with a mass of 1.41 ± 0.07 M⊙ and a radius of 2.21 ± 0.22 R⊙. The discovery of WASP-136b could help constrain the characteristics of the giant planet population around evolved stars. WASP-138b orbits an F7 star with a period of 3.63 days. Its radius agrees with theoretical values from standard models, suggesting the presence of a heavy element core with a mass of ~ 10 M⊕. The discovery of these new planets helps in exploring the diverse compositional range of short-period planets, and will aid our understanding of the physical characteristics of both gas giants and low-density planets.
Key words: planetary systems / stars: individual: WASP-127 / techniques: radial velocities / techniques: photometric / stars: individual: WASP-136 / stars: individual: WASP-138
Radial velocity and photometry tables are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/599/A3
© ESO, 2017
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