Radial velocities and S-index values for HR 5183

Based on two decades of radial velocity (RV) observations using Keck/High Resolution Echelle Spectrometer (HIRES) and McDonald/Tull, and more recent observations using the Automated Planet Finder, we found that the nearby star HR 5183 (HD 120066) hosts a 3 M_J_ minimum mass planet with an orbital period of 74_-22_^+43^ yr. The orbit is highly eccentric (e~0.84), shuttling the planet from within the orbit of Jupiter to beyond the orbit of Neptune.

Our careful survey design enabled high cadence observations before, during, and after the planet's periastron passage, yielding precise orbital parameter constraints. We searched for stellar or planetary companions that could have excited the planet's eccentricity, but found no candidates, potentially implying that the perturber was ejected from the system. We did identify a bound stellar companion more than 15000 au from the primary, but reasoned that it is currently too widely separated to have an appreciable effect on HR 5183 b.