The CORALIE survey for southern extrasolar planets. XVI. Discovery of a planetary system around HD 147018 and of two long period and massive planets orbiting HD 171238 and HD 204313

We report the detection of a double planetary system around HD 140718 as well as the discovery of two long period and massive planets orbiting HD 171238 and HD 204313. Those discoveries were made with the CORALIE Echelle spectrograph mounted on the 1.2-m Euler Swiss telescope located at La Silla Observatory, Chile. The planetary system orbiting the nearby G9 dwarf HD 147018 is composed of an eccentric inner planet (e = 0.47) with twice the mass of Jupiter (2.1 M$_Jup$) and with an orbital period of 44.24 days. The outer planet is even more massive (6.6 M$_Jup$) with a slightly eccentric orbit (e = 0.13) and a period of 1008 days. The planet orbiting HD 171238 has a minimum mass of 2.6 M$_Jup$, a period of 1523 days and an eccentricity of 0.40. It orbits a G8 dwarfs at 2.5 AU. The last planet, HD 204313 b, is a 4.0 M$_Jup$-planet with a period of 5.3 years and has a low eccentricity (e = 0.13). It orbits a G5 dwarfs at 3.1 AU. The three parent stars are metal rich, which further strengthens the case that massive planets tend to form around metal rich stars. The CORALIE radial velocity measurements discussed in this paper are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/511/A45 Based on observations collected at the ESO La Silla Observatory with the CORALIE Echelle spectrograph mounted on the Swiss telescope.