Radial velocity confirmation of Kepler-91 b: Additional evidence of its planetary nature using the Calar Alto/CAFE instrument

The object transiting the star <ASTROBJ>Kepler-91</ASTROBJ> 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 <ASTROBJ>Kepler-91b</ASTROBJ> 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<SUB>Jup</SUB> for the mass of Kepler-91b, in excellent agreement with our previous estimate that was based on the orbital brightness modulation.