The Pan-Pacific Planet Search III: Five companions orbiting giant stars

Abstract

We report a new giant planet orbiting the K giant HD 155233, as well as four stellar-mass companions from the Pan-Pacific Planet Search, a southern hemisphere radial velocity survey for planets orbiting nearby giants and subgiants. We also present updated velocities and a refined orbit for HD 47205b (7 CMa b), the first planet discovered by this survey. HD 155233b has a period of 885±63 days, eccentricity e = 0.03±0.20, and m sin i=2.0±0.5 M Jup . The stellar-mass companions range in m sin i from 0.066 M ⊙ to 0.33 M ⊙ . Whilst HD 104358B falls slightly below the traditional 0.08 M ⊙ hydrogen-burning mass limit, and is hence a brown dwarf candidate, we estimate only a 50% a priori probability of a truly substellar mass.