Truly eccentric – I. Revisiting eight single-eccentric planetary systems

We examine eight known single-eccentric planetary systems in light of recently released large data archives and new analysis techniques. For four of these systems (HD 7449, HD 65216, HD 89744, HD 92788) we find evidence for additional long-period companions. HD 65216c is a Jupiter analogue, with a period of 14.7 yr, e = 0.18, and m sin i of 2MJup, while the remaining candidate companions move on as-yet-incomplete orbits. Our results highlight the importance of revisiting the analysis of known exoplanetary systems when new data become available, particularly given the possibility that poorly sampled data might previously have led to the detection of a ‘false-positive’ single-eccentric planet, when the system in question actually contains two (or more) planets on near-circular orbits.