Observational approaches for resolving the solar wind acceleration mechanism

解决太阳风加速机制的观测方法

基本信息

批准号：
12440130
负责人：
KOJIMA Masayoshi
金额：
$ 7.17万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

(1) Properties of slow solar wind originated from a small coronal holeIt is well-known that fast solar wind originates from polar coronal holes. On the other hand, the origin of slow solar wind is complex in comparison with that of fast solar wind. Thus we have analyzed the origin of the slow solar wind by using IPS tomography velocity maps) photospheric magnetograms (Kitt Peak/NSO) and coronal hole boundary maps obtained from HeI1803 nm observation (Kitt Peal/NSO). We found several slow solar wind regions originated from small coronal holes at mid-latitude. Next we analyzed plasma parameters such as temperature, density, helium abundance, and their fluctuation levels using in situ measurements data. As results, we also found that plasma parameters of the slow solar wind originated from the small coronal hole resemble those of fast solar wind.(2) Spatial structure of ICMEsWe have analyzed in this study g-value data for two IOME events, which occurred on June 2000 and 1998 September. It is found from the model fitting analysis that an angular span for these ICME events is not isotropic. Such a troidal-shape structure also has been disclosed from the model fitting analysis for the ICME event associated with an X5.7/3B flare on July 14, 2000. The E-W angular span is about 7 larger than the N-S span for this event. While angular anisotropy estimated for 2000 June and 1998 Sep. events is smaller than one for the 2000 July event, we consider that such angular anisotropy might be a common feature for a certain class of ICME events. A possible agency to cause the angular anisotropy of ICME structure is either an interaction with the slow speed component of the solar wind or the effect of the magnetic flux rope.

（1）慢性太阳风的性质起源于小冠状孔，众所周知，快速太阳风起源于极性冠状孔。另一方面，与快速太阳风相比，慢太阳风的起源是复杂的。因此，我们通过使用IPS断层扫描速度图（KITT Peak/NSO）和从HEI1803 NM观察（Kitt Peal/NSO）获得的光磁图（Kitt Peak/NSO）和冠状孔边界图分析了慢性太阳风的起源。我们发现几个缓慢的太阳风区来自中纬度的小冠状孔。接下来，我们使用原位测量数据分析了血浆参数，例如温度，密度，氦气丰度及其波动水平。结果，我们还发现，慢性太阳风的等离子体参数起源于小冠状孔类似于快速太阳风。（2）ICMESWE的空间结构在这项研究中分析了两个IOME事件的G-Value数据，发生了两种IME事件，这发生了，这是如此2000年6月和1998年9月。从模型拟合分析中可以发现，这些ICME事件的角跨度不是各向同性的。从2000年7月14日，与X5.7/3B耀斑相关的ICME事件的模型拟合分析也已披露了这种三体形状结构。e-W Angular跨度比此事件的N-S跨度大约7。尽管估计2000年6月和1998年9月的角度各向异性的事件小于2000年7月事件的事件，但我们认为这种角各向异性可能是特定类别ICME事件的共同特征。引起ICME结构角各向异性的可能机构是与太阳风的慢速分量的相互作用，或者是磁通绳的效果。