Substellar Companions to Seven Evolved Intermediate-Mass Stars

We report on the detections of substellar companions orbiting around seven evolved intermediate-mass stars from precise Doppler measurements at Okayama Astrophysical Observatory. o UMa (G4 II-III) is a giant with a mass of 3.1M_', and hosts a planet with a minimum mass of m₂ sini = 4.1M_J in an orbit with a period P = 1630 d and an eccentricity e = 0.13. The star also exhibits a linear velocity trend, suggesting the existence of an outer, more massive companion. 75 Cet (G3 III:) is a 2.5M_⊙ giant hosting a planet of m₂ sini = 3.0M_J in a 692 d orbit with e = 0.12. The star also shows a possible additional periodicity of about 200 d and 1880 d with a velocity amplitude of ∼7-10 m s^-1, although these are not significant at this stage. ν Oph (K0 III) is a 3.0M_⊙ giant, and has two brown-dwarf companions of m₂ sini = 24M_J and 27M_J, in orbits with P = 530.3 d and 3190 d, and e = 0.126 and 0.17, respectively, which were independently announced by Quirrenbach, Reffert, and Bergmann (2011, AIP Conf. Proc. 1331, 102). The ratio of the periods is close to 1:6, suggesting that the companions are in mean motion resonance. We also independently confirmed planets around κ CrB (K0 III-IV) and HD 210702 (K1 IV), which were announced by Johnson et al. (2008, ApJ, 675, 784) and Johnson et al. (2007a, ApJ, 665, 785), respectively. All of the orbital parameters we obtained are consistent with the previous results.