55Cancri系是已发现的太阳系外众多行星系中的一个,其中心天体类似太阳,周围有4颗巨行星.最内部的行星e是2004年新发现的,质量与海王星类似,但到中心天体的距离却仅为水星到太阳的1/10.这类行星在外太阳系具有典型性.为了探索该类行星的轨道稳定性问题,本文对行星e进行了10年的轨道演化数值模拟.结果表明:除了与相邻行星的2:11共振点外,行星e半长径在小于0.0388AU范围内的轨道都是稳定的.该结果意味着,在类太阳恒星的周围,类海王星质量的行星可以稳定在近距离的轨道上.
55 Cancri four giant planets system is one of known extrosolar planetary systems. It has the like-sun star and The planet e is the innermost one,with like-Neptune mass and the distance form the star equal to tenth that of Mercury form the sun,ls newly discovered in 2004. The class of the planets occupies a larger number in extrosolar. To study the orbital stability of the class of the planets, we study the orbital evolution of the planet e by numerical integration for 10^6 years. The result shows that the planet e is stable if a〈0. 0388AU expect the resonance point between planets e and b. The result also indicates that the Neptune-mass planets can be stable on the obits closer to the like-sun.