The Unseen Companion of HD 140913: Another Brown Dwarf Candidate

For more than 10 years we have been monitoring the radial velocity of HD 140913 as part of an effort to set up a new system of radial-velocity standard stars for the IAU. Data from the Digital Speedometers at CfA and from the radial-velocity spectrometer at DAO independently give the same low-amplitude spectroscopic orbit with period 147 days, amplitude 1.8 km/s, eccentricity 0.5, and minimum mass for the companion of 37 Jupiter masses. Together with HD 114762, this makes two G dwarfs among the IAU radial-velocity standards with low-mass companions which are probably below the substellar limit of 85 Jupiter masses.