ABSTRACT. We numerically investigated the dynamical architecture of 47 UMa with the planetary configuration of the best-fit orbital solutions by Fischer and coworkers. We systematically studied the existence of Earth-like planets in the region 0.05 AU ≤ a ≤ 2.0 AU for 47 UMa with numerical simulations and also explored the packed planetary geometry and Trojan planets in the system. In the simulations, we found that "hot Earths" at 0.05 AU ≤ a < 0.4 AU can dynamically survive for at least 1 Myr. The Earth-like planets can eventually remain in the system for 10 Myr in areas involved in mean motion resonances (MMRs; e.g., 3 : 2 MMR) with the inner companion. Moreover, we showed that the 2 : 1 and 3 : 1 resonances are on the fringe of stability, while the 5 : 2 MMR is unstable. In addition, the 2 : 1 MMR marks out a remarkable boundary between chaotic and regular motions: inside, most of the orbits can survive, but outside, they are mostly lost in the orbital evolution. In a dynamical sense, the most likely candidates for habitable environments are Earth-like planets with orbits in the ranges 0.8 AU ≤ a < 1.0 AU and 1.0 AU < a < 1.30 AU (except the 5 : 2 MMR and several unstable cases) with relatively low eccentricities. The Trojan planets with low eccentricities and inclinations can secularly last at the triangular equilibrium points of the two massive planets. Hence, the 47 UMa planetary system may be a close analog to our solar system, bearing a similar dynamical structure.

Subject headings: celestial mechanics; methods: N-body simulations; planetary systems; stars: individual (47 Ursae Majoris)

Print publication: Issue 2 (2005 October 1)
Received 2004 December 10, accepted for publication 2005 June 15