Orbital evolution of the best-fit system of two planets that started off on circular orbits but with unconstrained periods. Left: 1-year excerpt from the simulation. Right: excerpt for the following 999 yr. Both in the left and right part of the figure, the individual panels show from top to bottom the short-term variation of the semi-major axes a₁ and a₂, of the eccentricities e₁ and e₂, and of the difference of the longitudes of periastron ω₂ − ω₁. The last quantity is not plotted when one of the eccenticities are close to zero (e₁ or e₂< 0.0001) since then the longitude of periastron is undefined (hence the gaps in the lower left panel). The variation pattern of these parameters shows various periodicites of which the following can be most easily seen here: 15 d and 104 d (all five parameters, left part of figure), and 65 yr (e₁ and ω₂ − ω₁; right part of figure).