Stability and Formation of the Resonant System HD 73526

TL;DR

This paper investigates the stability and formation of the resonant exoplanet system HD 73526, demonstrating that stable, non-chaotic orbital solutions are consistent with observations and can result from combined migration and perturbative processes.

Contribution

It presents new stable orbital solutions for HD 73526 and explores formation scenarios involving planetary migration and perturbative effects, supported by comprehensive simulations.

Findings

HD 73526's orbital data can be consistent with a stable 2:1 resonance.

The system's dynamical state may result from combined migration and scattering events.

Stable, coplanar resonant configurations are possible for HD 73526.

Abstract

Based on radial velocity measurements it has been found recently that the two giant planets detected around the star HD 73526 are in 2:1 resonance. However, as our numerical integration shows, the derived orbital data for this system result in chaotic behavior of the giant planets, which is uncommon among the resonant extrasolar planetary systems. We intend to present regular (non-chaotic) orbital solutions for the giant planets in the system HD 73526 and offer formation scenarios based on combining planetary migration and sudden perturbative effects such as planet-planet scattering or rapid dispersal of the protoplanetary disk. A comparison with the already studied resonant system HD 128311, exhibiting similar behavior, is also done. The new sets of orbital solutions have been derived by the Systemic Console (www.oklo.org). The stability of these solutions has been investigated by the Relative Lyapunov indicator, while the migration and scattering effects are studied by gravitational N-body simulations applying non-conservative forces as well. Additionally, hydrodynamic simulations of embedded planets in protoplanetary disks are performed to follow the capture into resonance. For the system HD 73526 we demonstrate that the observational radial velocity data are consistent with a coplanar planetary system engaged in a stable 2:1 resonance exhibiting apsidal corotation. We have shown that, similarly to the system HD 128311, the present dynamical state of HD 73526 could be the result of a mixed evolutionary process melting together planetary migration and a perturbative event.