We report the detection of three extrasolar planets from the Lick and Keck observatories. The F8 V star HD 40979 has a companion with orbital period P = 263.1 ± 3 days, eccentricity e = 0.25 ± 0.05, and velocity semiamplitude K = 101.2 ± 5.6 m s-1. The inferred semimajor axis is 0.83 AU and M sin i = 3.28MJup. Observations of planetary companions orbiting the G6 V star HD 12661 and the G4 IV star HD 38529 have already been published, and here we report additional, longer period companions for both of these stars. The outer companion to HD 12661 has Pc = 1444.5 ± 12.5 days, ec = 0.20 ± 0.04, and Kc = 27.6 ± 2.5 m s-1. Adopting a stellar mass of 1.07 M⊙, we find Mc sin i = 1.57MJup and a semimajor axis of 2.56 AU. The second companion to HD 38529 has Pc = 2174 ± 30 days, ec = 0.36 ± 0.05, and Kc = 170.5 ± 9 m s-1. The assumed mass of 1.39 M⊙ for HD 38529 yields Mc sin i = 12.7MJup and a semimajor axis of 3.68 AU. Photometric observations at Fairborn Observatory reveal low-amplitude brightness variations in HD 40979 and HD 38529 due to rotational modulation in the visibility of photospheric starspots, and they yield rotation periods of 7.0 and 35.7 days, respectively, very different from the planetary orbital periods. The orbital parameters of these two systems are compared with updated parameters for all of the known multiple-planet systems. Updated velocities are provided for the Υ Andromedae system.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science