伽利略卫星的内部结构模型以及平衡形状参数

木星的４颗大卫星都是同步轨旋卫星，常被称为伽利略卫星．美国发射的伽利略飞船自１９９５年１２月抵达木星系统后，近几年来对木星的４颗伽利略卫星进行了一系列的探测．利用飞船探测的最新资料（参看表１）作为约束条件，建立了伽利略卫星的一组内部结构模型（参看表３～６）；然后按照同步轨旋卫星的形状理论公式计算了它们的平衡形状参数（参看表７），以木卫一为例，其三轴椭球体的 ３个油分别是 １８３０．７３，１８１９．８９和 １８１６．２７ ｋｍ；最后，将计算结果与已有的研究结果作了比较和讨论．

A Study of Internal Structure Models and Equilibrium Shapes of Galilean Satellites

The Galilean satellites Ic, Europa, Ganymede, and Callisto are orbiting synchronously (in resonance 1: 1), i. e. the angular velocity to of the satellite is equal to its orbital mean motion n. The rotation axes of Jupiter and Galilean satellites are nearly parallel, and the inclination of the orbital plane of satellites is small enough, i. e. the satellites assumed to be orbiting in the equatorial plane of Jupiter. The eccentricity of the orbit is small and it can be assumed to be circular in the figure theory. Galileo mission to Jupiter has allowed major advances in our understanding of Galilean satellites over the past few years. Particularly exciting findings include the evidence for internal liquid water oceans in Europa and Callisto, detection of a strong intrinsic magnetic field within Ganymede, and discovery of high - temperature volcanic eruption on Io. The primary objectives of the present paper are three- fold. First, a set of interior models of Galilean satellites is constructed using the undated physical parameters (of. Table 1). Regarding the mean density and the moment factor, I/AN2, as two constrained conditions, and using the state equations of the constitutive material for the satellites, one can then obtain the profile of density p(r) of the bodies. Secondly, the parameters of equilibrium shape can be obtained by using Equations (12) and (14) in this paper as well. Taking Io as an example we conclude the equilibrium shape is 1 830. 73, 1 819. 89, 1 816. 27 km, and the (a- c) is 14. 46 km. And thirdly, a comparison with other results is made.