We report the strategy and results of our radial velocity follow-up campaign with the SOPHIE spectrograph ( 1.93-m OHP ) of four transiting planetary candidates discovered by the Kepler space mission .
We discuss the selection of the candidates KOI-428 , KOI-410 , KOI-552 , and KOI-423 .
KOI-428 was established as a hot Jupiter transiting the largest and the most evolved star discovered so far and is described by Santerne et al .
( 2011a ) .
KOI-410 does not present radial velocity change greater than 120 m s ^ { -1 } , which allows us to exclude at 3 \sigma a transiting companion heavier than 3.4 \mathrm { M } _ { Jup } .
KOI-552b appears to be a transiting low-mass star with a mass ratio of 0.15 .
KOI-423b is a new transiting companion in the overlapping region between massive planets and brown dwarfs .
With a radius of 1.22 \pm 0.11 \mathrm { R } _ { Jup } and a mass of 18.0 \pm 0.92 \mathrm { M } _ { Jup } , KOI-423b is orbiting an F7IV star with a period of 21.0874 \pm 0.0002 days and an eccentricity of 0.12 \pm 0.02 .
From the four selected Kepler candidates , at least three of them have a Jupiter-size transiting companion , but two of them are not in the mass domain of Jupiter-like planets .
KOI-423b and KOI-522b are members of a growing population of known massive companions orbiting close to an F-type star .
This population currently appears to be absent around G-type stars , possibly due to their rapid braking and the engulfment of their companions by tidal decay .