Grigg-Skjellerup彗星新生离子激发低频电磁波性质

PROPERTIES OF LOW FREQUENCY ELECTROMAGNETIC WAVES AT COMET GRIGG-SKJELLERUP

本文运用磁场的最小方差分析法和磁场—电子密度的相关分析法分析了欧洲空间局Giotto飞船对P／Grigg-Skjellerup（简称G-S）彗星弓激波附近磁场和电子能流的部分观测数据．结果表明彗星附近存在大量的频率靠近新生水族离子回旋频率的波动，它们是由彗星新生水族离子环流激发的低频左旋电磁波．波在近似平行于磁场方向传播，斜传播角小于15°．电子数据和磁场数据相关分析表明即使在离彗星很远的地方仍然存在压缩波．

In this paper by using the minimum variance method and cross cormlation analysis, we analyze the data of magnetic field and electron flux obtained by the spacecraft Giotto at comet P/Grigg-Skjellerup. The results show that there exist a large amount of low frequency waves for a weakly active comet at frequencies close to the local water group ion cyclotron frequencies. These low frequency left-handed electromagnetic waves are generated by cometary newborn ring ions. The direction of propagation is not exactly parallel to the magnetic field direction, but not far from it.Cross-analysis of the electron parameters with the magnehc field reveals the existence of a compressive wave component even at large distance from the nucleus.