Resonances of low orders in the planetary system of HD37124

TL;DR

This paper analyzes radial velocity data for HD37124, revealing two stable high-eccentricity planetary configurations involving mean-motion and apsidal resonances, and discusses possible non-resonant scenarios.

Contribution

It identifies two distinct stable high-eccentricity orbital solutions with specific resonances for HD37124's planets, expanding understanding of its planetary dynamics.

Findings

Two families of stable high-eccentricity solutions found

Outer planets in 2/1 and 5/2 mean-motion resonances

Possible non-resonant configurations with lower eccentricities

Abstract

The full set of published radial velocity data (52 measurements from Keck + 58 ones from ELODIE + 17 ones from CORALIE) for the star HD37124 is analysed. Two families of dynamically stable high-eccentricity orbital solutions for the planetary system are found. In the first one, the outer planets c and d are trapped in the 2/1 mean-motion resonance. The second family of solutions corresponds to the 5/2 mean-motion resonance between these planets. In both families, the planets are locked in (or close to) an apsidal corotation resonance. In the case of the 2/1 MMR, it is an asymmetric apsidal corotation (with the difference between the longitudes of periastra $\Delta\omega\sim 60^\circ$), whereas in the case of the 5/2 MMR it is a symmetric antialigned one ($\Delta\omega = 180^\circ$). It remains also possible that the two outer planets are not trapped in an orbital resonance. Then their orbital eccentricities should be relatively small (less than, say, 0.15) and the ratio of their orbital periods is unlikely to exceed $2.3-2.5$.