On the Extrasolar Multiplanet System around HD 160691

We re-analyze the precision radial velocity (RV) observations of HD160691 (muAra) by the Anglo-Australian Planet Search Team. The star is supposed to hosttwo Jovian companions (HD160691b, HD160691c) in long-period orbits about 630days and about 2500 days, respectively) and a hot-Neptune (HD160691d) in about9 days orbit. We perform a global search for the best fits in the orbitalparameters space with a hybrid code employing the genetic algorithm and simplexmethod. The stability of Keplerian fits is verified with the N-body model ofthe RV signal that takes into account the dynamical constraints (so called GAMPmethod). Our analysis reveals a signature of the fourth, yet unconfirmed,Jupiter-like planet HD160691e in about 307 days orbit. Overall, the globalarchitecture of four-planet configuration recalls the Solar system. Allcompanions of mu Ara move in quasi-circular orbits. The orbits of two innerJovian planets are close to the 2:1 mean motion resonance. The alternativethree-planet system involves two Jovian planets in eccentric orbits (e about0.3), close to the 4:1 MMR, but it yields a significantly worse fit to thedata. We also verify a hypothesis of the 1:1 MMR in the subsystem of two innerJovian planets in the four-planet model.