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

TL;DR

This paper reports the discovery of multiple long-period, massive exoplanets around three metal-rich stars using the CORALIE spectrograph, expanding knowledge of planetary system architectures.

Contribution

First detection of a double planetary system around HD 147018 and new massive planets around HD 171238 and HD 204313 using the CORALIE spectrograph.

Findings

Discovered a double planetary system around HD 147018.

Identified massive planets orbiting HD 171238 and HD 204313.

All host stars are metal-rich, supporting the link between stellar metallicity and giant planet formation.

Abstract

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 MJup ) and with an orbital period of 44.24 days. The outer planet is even more massive (6.6 MJup) 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 MJup, 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 MJup -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 strengthened the case that massive planets tend to form around metal rich stars.