We introduce the Pan-Pacific Planet Search, a survey of 170 metal-rich Southern hemisphere subgiants using the 3.9m Anglo-Australian Telescope. We report the first discovery from this program, a giant planet orbiting 7 CMa (HD 47205) with a period of 763±17 days, eccentricity e = 0.14±0.06, and m sin i=2.6±0.6 M Jup . The host star is a K giant with a mass of 1.5±0.3 M ⊙ and metallicity [Fe/H]=0.21±0.10. The mass and period of 7 CMa b are typical of planets which have been found to orbit intermediate-mass stars (M * > 1.3M ⊙ ). Hipparcos photometry shows this star to be stable to 0.0004 mag on the radialvelocity period, giving confidence that this signal can be attributed to reflex motion caused by an orbiting planet.

Context. Exoplanet searches have revealed interesting correlations between the stellar properties and the occurrence rate of planets. In particular, different independent surveys have demonstrated that giant planets are preferentially found around metal-rich stars and that their fraction increases with the stellar mass. Aims. During the past six years we have conducted a radial velocity follow-up program of 166 giant stars to detect substellar companions and to characterize their orbital properties. Using this information, we aim to study the role of the stellar evolution in the orbital parameters of the companions and to unveil possible correlations between the stellar properties and the occurrence rate of giant planets. Methods. We took multi-epoch spectra using FEROS and CHIRON for all of our targets, from which we computed precision radial velocities and derived atmospheric and physical parameters. Additionally, velocities computed from UCLES spectra are presented here. By studying the periodic radial velocity signals, we detected the presence of several substellar companions. Results. We present four new planetary systems around the giant stars HIP 8541, HIP 74890, HIP 84056, and HIP 95124. Additionally, we study the correlation between the occurrence rate of giant planets with the stellar mass and metallicity of our targets. We find that giant planets are more frequent around metal-rich stars, reaching a peak in the detection of f = 16.7 +15.5 −5.9 % around stars with [Fe/H] ∼ 0.35 dex. Similarly, we observe a positive correlation of the planet occurrence rate with the stellar mass, between M ∼ 1.0 and 2.1 M , with a maximum of f = 13.0Conclusions. We conclude that giant planets are preferentially formed around metal-rich stars. In addition, we conclude that they are more efficiently formed around more massive stars, in the stellar mass range of ∼1.0-2.1 M . These observational results confirm previous findings for solar-type and post-MS hosting stars, and provide further support to the core-accretion formation model.

The lithium abundances for 378 G/K giants are derived with non-LTE correction considered. Among these, there are 23 stars that host planetary systems. The lithium abundance is investigated, as a function of metallicity, effective temperature, and rotational velocity, as well as the impact of a giant planet on G/K giants. The results show that the lithium abundance is a function of metallicity and effective temperature. The lithium abundance has no correlation with rotational velocity at vsini < 10 km s −1 . Giants with planets present lower lithium abundance and slow rotational velocity (vsini < 4 km s −1 ). Our sample includes three Li-rich G/K giants, 36 Li-normal stars and 339 Li-depleted stars. The fraction of Li-rich stars in this sample agrees with the general rate of less than 1% in literature, and the stars that show normal amounts of Li are supposed to possess the same abundance at the current interstellar medium. For the Lidepleted giants, Li deficiency may have already taken place at the main sequence stage for many intermediate-mass (1.5-5 M ⊙ ) G/K giants. Finally, we present the lithium abundance and kinematic parameters for an enlarged sample of 565 giants using a compilation of literature, and confirm that the lithium abundance is a function of metallicity and effective temperature. With the enlarged sample, we investigate the differences between the lithium abundance in thin-/thick-disk giants, which indicate that the lithium abundance in thick-disk giants is more depleted than that in thin-disk giants.