HD 60532, a planetary system in a 3:1 mean motion resonance

A recent paper has reported that there is a planetary system around the star HD 60532, composed of two giant planets in a possible 3:1 mean motion resonance, which should be confirmed within the next decade. Here we show that the analysis of the global dynamics of the system already allows this resonance to be confirmed. The present best fit to the data corresponds to this resonant configuration, and the system is stable for at least 5 Gyr. The 3:1 resonance is so robust that stability is still possible for a wide variety of orbital parameters around the best-fit solution and would also be if the inclination of the system orbital plane is as small as 15° with respect to the plane of the sky. Moreover, if the inclination is taken as a free parameter in the adjustment to observations, we find an inclination ~20°, which corresponds to Mb = 3.1 MJup and Mc = 7.4 MJup for the planetary companions.