New planetary systems from the Calan-Hertfordshire Extrasolar planet search

Abstract

We report the discovery of eight new giant planets, and updated orbits for four known planets,orbiting dwarf and subgiant stars using the CORALIE, HARPS, and MIKE instruments aspart of the Calan–Hertfordshire Extrasolar Planet Search. The planets have masses in therange 1.1–5.4MJ’s, orbital periods from 40 to 2900 d, and eccentricities from 0.0 to 0.6. Theyinclude a double-planet system orbiting the most massive star in our sample (HD147873),two eccentric giant planets (HD128356band HD154672b), and a rare 14 Herculis analogue(HD224538b). We highlight some population correlations from the sample of radial velocitydetected planets orbiting nearby stars, including the mass function exponential distribution,confirmation of the growing body of evidence that low-mass planets tend to be found orbitingmore metal-poor stars than giant planets, and a possible period–metallicity correlation forplanets with masses>0.1MJ, based on a metallicity difference of 0.16 dex between thepopulation of planets with orbital periods less than 100 d and those with orbital periods greaterthan 100 d.