1 Department of PhysicsUniversity of Warwick, Gibbet Hill Road, Coventry, CV4 7AL, UK
2 Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, 13388 Marseille, France
3 Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, 4150-762 Porto, Portugal
4 Departamento de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC campus 28691 Villanueva de la Cañada ( Madrid), Spain
5 Université. Grenoble Alpes, IPAG, 38000 Grenoble, France
6 CNRS, IPAG, 38000 Grenoble, France
7 INAF−Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese, Italy
8 Observatoire Astronomique de l’Université de Genève, 51 chemin des Maillettes, 1290 Versoix, Switzerland
9 Institut d’Astrophysique de Paris, UMR7095 CNRS, Université Pierre & Marie Curie, 98bis boulevard Arago, 75014 Paris, France
10 Observatoire de Haute-Provence, Université d’Aix-Marseille & CNRS, 04870 Saint Michel l’Observatoire, France
11 CNRS, Canada-France-Hawaii Telescope Corporation, 65-1238 Mamalahoa Hwy., Kamuela, HI 96743, USA
Received: 2 March 2015
Accepted: 18 August 2015
Aims. The K2 mission has recently begun to discover new and diverse planetary systems. In December 2014, Campaign 1 data from the mission was released, providing high-precision photometry for ~22 000 objects over an 80-day timespan. We searched these data with the aim of detecting more important new objects.
Methods. Our search through two separate pipelines led to the independent discovery of K2-19b and c, a two-planet system of Neptune-sized objects (4.2 and 7.2 R⊕), orbiting a K dwarf extremely close to the 3:2 mean motion resonance. The two planets each show transits, sometimes simultaneously owing to their proximity to resonance and the alignment of conjunctions.
Results. We obtained further ground-based photometry of the larger planet with the NITES telescope, demonstrating the presence of large transit timing variations (TTVs), and used the observed TTVs to place mass constraints on the transiting objects under the hypothesis that the objects are near but not in resonance. We then statistically validated the planets through the PASTIS tool, independently of the TTV analysis.
Key words: planets and satellites: individual: EPIC201505350c / planets and satellites: detection / planets and satellites: general / planets and satellites: dynamical evolution and stability / planets and satellites: individual: EPIC201505350b
Using observations made with SOPHIE on the 1.93-m telescope at Observatoire de Haute-Provence (CNRS), France.
Appendix is available in electronic form at http://www.aanda.org
A table of the data plotted in Fig. 1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (126.96.36.199) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/582/A33
© ESO, 2015