Letter to the Editor

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

¹ ASD, IMCCE, CNRS-UMR8028, Observatoire de Paris, UPMC, 77 avenue Denfert-Rochereau, 75014 Paris, France e-mail: laskar@imcce.fr
² Departamento de Física, Universidade de Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal e-mail: correia@ua.pt

Received: 20 January 2009
Accepted: 3 February 2009

Abstract

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 M_b = 3.1 M_Jup and M_c = 7.4 M_Jup for the planetary companions.