Left: RV data of HD 12438 obtained with FEROS and HARPS during more than nine years. The line represents the orbit with lower rms obtained for a period of 11.4 years fixing the eccentricity to e = 0. The high scatter around this line is mainly caused by stellar oscillations. Right: squared visibilities of HD 12438 observed on October 6, 2008. The lines are the visibilities of a binary (see Eq. (5)), for the baselines of the observation, obtained with a separation of the components of  ~ 12 mas and a position angle of 120^o.