木星极光区亮斑形成机制

The causation of bright spots polarward of Jupiter s aurora oval

近年来一系列的木星照片显示,除了主极光卵和卫星足迹外,在极光卵内还有极区发射.学者基本认为这是由中磁尾的磁场活动引起的.本文建立一个具有离心力效应的木星稳态磁场模型.并以该模型给出的磁场结果为基础,利用Hill等人1979年总结的木星磁层较差自转的结果进行模拟分析.结果显示在约54R_j(R_j为木星平均半径)至60R_j的木星磁场由于较差自转形成涡旋结构,其形状约为5R_j的圆形.由于磁力线的扭曲引发大小为数十万安培的电流注入极区电离层,与中性粒子相互作用,从而形成极光卵内的亮斑.

An extended series of images have shown that, besides the main aurora oval and satellite footprints, there is polar emission in the aurora oval, which is believed by some scholars that it results from the activities of the middle magnetotail. This paper aims to construct a selfconsistent stationary model of the Jupiterrs magnetosphere include the centrifugal force, and make analysis of numerical simulation based on the result of magnetic field and the differential rotation theory of Hill in 1979. It is shown that because of the differential rotation, the middle magnetotail （about 54Rj to 60Ri） forms a shape of volution, which looks like a round with five Jupitersr radius. It generates a current about 2.9×0^5 A return to the polar ionosphere, and a bright spot inside the auroral oval has been observed.