干旱区生态环境知识资源中心

During the late stage of planet formation, when Mars-sized cores appear, interactions among planetary cores can excite their orbital eccentricities, accelerate their merging, and thus sculpt their final orbital architecture. This study contributes to the final assembling of planetary systems with N-body simulations, including the type I or II migration of planets and gas accretion of massive cores in a viscous disk. Statistics on the final distributions of planetary masses, semimajor axes, and eccentricities are derived and are comparable to those of the observed systems. Our simulations predict some new orbital signatures of planetary systems around solar mass stars: 36% of the surviving planets are giant planets (> 10M(circle plus)). Most of the massive giant planets (> 30 M-circle plus) are located at 1-10 AU. Terrestrial planets are distributed more or less evenly at <1-2 AU. Planets in inner orbits may accumulate at the inner edges of either the protostellar disk (3-5 days) or its magnetorotational instability dead zone (30-50 days). There is a planet desert in the mass-eccentricity diagram, i.e., a lack of planets with masses 0.005-0.08M(J) in highly eccentric orbits (e > 0.3-0.4). The average eccentricity (similar to 0.15) of the giant planets (> 10M(circle plus)) is greater than that (similar to 0.05) of the terrestrial planets (< 10M(circle plus)). A planetary system with more planets tends to have smaller planet masses and orbital eccentricities on average.