Investigatin of the origin of Jupiter's aurora : in coordination with distant-encounter of Ulysses

我们研究了太阳风参数与木星红外极光积分通量之间的相关性，以找出它们是呈正相关还是负相关。在过去，观察者提出了“正”相关性(尽管很弱)，另一方面，理论家们提出了一些模型，认为太阳风和木星的极光响应之间存在负相关。本研究采用观测与模拟相结合的方法，通过对日本4个观测点的行星际闪烁进行MHD层析成像分析，确定了太阳风参数。还确定了行星际磁场(IMF)参数。我们从我们的档案中选取了木星数据，并将4个数据集(1998-2000年获得)与太阳风数据进行了比较。我们的结论包括：(1)两个数据集，每个数据集都有多个晚上的木星观测，表明与太阳风冲压有很好的正相关。(2)一个数据集表示“负”相关，然而，它只包括两个晚上的木星观测，而在此期间缺乏IPS测量，使我们无法得出可靠的结论。(3)在4组数据中，极光亮度可以明显地分为两组：第一组是较亮的极光，与偏北的IMF有关；第二组是较暗的极光，与偏南的IMF有关。这种关系与木星的磁场与地球的磁场具有相反的极性是一致的。上面最后一个结论(与IMF极性的关联)是最重要的，并首次基于观测得出。有了通过这项研究开发的这些有用的工具，我们应该能够继续增加我们关于太阳-风磁层相互作用的知识。

We have investigated the correlation between the solar wind parameters and integrated flux of Jupiter's infrared aurora to find out if they show "positive" or "negative" correlation. In the past, observers suggested "positive" correlations (weak, though), and on the other hand, theoretists proposed models which expect negative correlations between the solar wind and Jupiter's auroral response. This study is to clarify the case using observations and simulations.The solar wind parameters have been determined based on MHD tomography analysis of interplanetary scintillations which are measured at 4 observing sites in Japan. Parameters on interplanetary magnetic field (IMF) have also been determined. Jupiter data have been selected from our archives and 4 data sets (acquired in 1998-2000) were compared with the solar-wind data.Our conclusions include :(1) Two data sets, each of which has many nights of Jupiter observations, indicate a good "positive" correlation with the solar-wind ram pressure.(2) One data set is indicative of "negative" correlation, however, it includes only 2 nights of Jupiter observations, and lack of IPS measurements just before this period prevents us from solid conclusions. Another set shows nearly constant aurora brightness in spite of a dramatic increase of the solar-wind ram pressure.(3) Among all of 4 data sets, the aurora brightness can be clearly divided in 2 groups : the first one is "brighter" aurora and is associated to northward IMF, and the second one is "dimmer" aurora associated to southward IMF. Such relationship is consistent with the fact that Jupiter's magnetic field has an opposite polarity compared to the Earth's one.The last conclusion in the above (correlation with IMF polarity) is the most important and is for the first time indicated based on the observations. With such useful tools, developed through this study, we should be able to continue increasing our knowledge about the solar-wind magnetosphere interactions.