摘要
本文根据金星空间探测器对金星重力场的最新探测结果,讨论了由于金星重力场的非对称性引起的对金星自转演化中的影响。计算结果表明,金星自转速率具有周期性变化为:根据金星内部构成的模型力学性质,计算了上式引起的金星的永久变形,从而导致其对自转轴惯性矩的变化。根据文[1]的结论,金星形成初期为快速顺向自转的天体,取其平均初始自转周期T0=15小时[2-4],则可求得其自转速率的长期减慢为:ωg=-6.2155×10-22弧度/秒2。如果金星形成后其重力场的变化不大,那么由图1结果可知ωg对金星初期的自转速率变化曾起过一定的作用。
In this paper, based on the results of gravitational field of the Venus measured by the Venera probes, the effect on the rotational evolution of the Venus caused by the non-zonal harmonics in Venus gravitaitonal field has been estimated. The periodic change of the rotational rate of the Venus can be expressed as.
where T is hour angle of the Sun with reference to the prime meridian of the Venus. Using the mechanical modal of Venus internal structure could be changed by the permanent deformation of the Venus caused by the change of angular momentum period term mentioned aboove. Taking the original anticlockwise rotation period of 15h for the Venus, we can obtain that the angrlar acceleration ωθ is about 7.116 × 10-22/s2. If we take into account the three torques: the solar gravitation tide, the zonal wind of the Venus, and its non-zonal gravitational field, the time of evolution from quick anticlockwise rotation to the present period of rotation of 243 days is about 2.82×10θyr.
出处
《中国科学院上海天文台年刊》
1989年第10期29-33,共5页
Annals Shanghai Astronomical Observatory Chinese Academy of Sciences
