Planetary companions to HD 12661, HD 92788, and HD 38529 and variations inKeplerian residuals of extrasolar planets

Precision Doppler observations at the Lick and Keck observatories have reve aled Keplerian velocity variations in the stars HD 12661, HD 92788, and HD 38529. HD 12661 (G6 V) has an orbital period of 252.7 +/- 2.7 days, velocit y semiamplitude K = 88.4 +/- 2.0 m s(-1), and orbital eccentricity e = 0.23 +/- 0.024. Adopting a stellar mass of 1.07 M-., we infer a companion mass of M sin i = 2.79 M-J and a semimajor axis of a = 0.79 AU. HD 92788 (G5 V) has an orbital period of 326.7 +/- 3.2 days, velocity semiamplitude K = 99. 9 +/- 2.4, and orbital eccentricity e = 0.30 +/- 0.06. The adopted stellar mass of 1.06 M-. yields a companion mass of M sin i = 3.34 M-J and a semima jor axis of a = 0.95 AU. HD 38529 (G4 IV) has an orbital period of 14.3 +/- 0.8 days, velocity semiamplitude K= 53.8 +/- 2.0 m s(-1), and eccentricity e = 0.27 +/- 0.03. The stellar mass of 1.4 M-. sets M sin i = 0.77 M-J, wi th a semimajor axis of a = 0.13 AU for this companion. In addition to the 1 4.3 day periodicity, the velocity residuals for HD 38529 show curvature ove r the three years of observations. Based on a measurement of Ca II H and K emission, all three stars are chromospherically inactive. Based on both spe ctral synthesis modeling and narrowband photometry, HD 12661, HD 92788, and HD 38529 all appear to be metal-rich stars, reinforcing the correlation of high metallicity in the host stars of gas giant extrasolar planets. We exa mine the velocity residuals to the Keplerian fits for a subsample of 12 pla net-bearing stars that have been observed longer than two years at the Lick Observatory. Five of the 12 (Ups Andromedae, tau Boo, 55 Cnc, HD 217107, a nd HD 38529) exhibit coherent variations in the residual velocities that ar e consistent with additional companions. Except for Upsilon Andromedae, the source of the velocity variation remains speculative pending completion of one full orbit. GJ 876 exhibits residual velocities with high rms scatter (24 m s(-1)), lacking identifiable coherence. The residual velocities for s ix of the 12 stars (51 Peg, 70 Vir, 16 Cyg B, rho CrB, 47 UMa, and HD 19501 9) exhibit rms velocity scatter of similar to7 m s(-1), consistent with err ors. The residual velocity trends suggest that known planet-bearing stars a ppear to harbor a distant (>3 AU) detectable companion more often than othe r stars in our planet survey.