We report the detection of a low-mass companion orbiting the solar-type star HD 178911B , the distant component of the stellar triple system HD 178911 .
The variability of HD 178911B was first detected using radial-velocity measurements obtained with the HIRES spectrograph mounted on the 10–m Keck 1 telescope at the W.M .
Keck Observatory ( Hawaii , USA ) .
We then started an intense radial-velocity follow up of the star with the ELODIE echelle spectrograph mounted on the 1.93–m telescope at the Observatoire de Haute-Provence ( France ) in order to derive its orbital solution .
The detected planet candidate has an orbital period of 71.5 days and a minimum mass of 6.3 { \mathrm { M } _ { Jup } } .
We performed a spectral analysis of the star , which shows that the lithium abundances in the system are similar to those in another known planet-hosting wide binary stellar system , 16 Cyg .
In both systems the lithium is undetected in the atmosphere of the visual secondary harboring the planetary companion , but is easily detected in the spectrum of the visual primary .
We discuss this similarity and its ramifications .