Radial velocity confirmation of Kepler-91 b

Additional evidence of its planetary nature using the Calar Alto/CAFE instrument

¹ Depto. de Astrofísica, Centro de Astrobiología (CSIC-INTA), ESAC campus, 28691 Villanueva de la Cañada ( Madrid), Spain
e-mail: Jorge.Lillo@cab.inta-csic.es
² Max Planck Institute for Astronomy, Königstuhl 17, 69117 Heidelberg, Germany
³ Centro de Astrofísica, Universidade do Porto, Rua das Estrelas, 4150-762 Porto, Portugal
⁴ Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, 4150-762 Porto, Portugal
⁵ Centro Astronómico Hispano-Alemán (CAHA), Calar Alto Observatory, c/ Jesús Durbán Remón 2-2, 04004 Almería, Spain
⁶ Instituto de Astronomía, Universidad Nacional Autonóma de México, A.P. 70-264, 04510 México, D.F, Mexico

Received: 11 July 2014
Accepted: 31 July 2014

Abstract

The object transiting the star Kepler-91 was recently assessed as being of planetary nature. The confirmation was achieved by analysing the light-curve modulations observed in the Kepler data. However, quasi-simultaneous studies claimed a self-luminous nature for this object, thus rejecting it as a planet. In this work, we apply anindependent approach to confirm the planetary mass of Kepler-91b by using multi-epoch high-resolution spectroscopy obtained with the Calar Alto Fiber-fed Echelle spectrograph (CAFE). We obtain the physical and orbital parameters with the radial velocity technique. In particular, we derive a value of 1.09 ± 0.20 M_Jup for the mass of Kepler-91b, in excellent agreement with our previous estimate that was based on the orbital brightness modulation.