Study of solar wind acceleration mechanisms with coordinated interplanetary scintillation observations at different frequencies.

利用不同频率协调行星际闪烁观测研究太阳风加速机制。

基本信息

批准号：
04640424
负责人：
KOJIMA Masayoshi
金额：
$ 1.22万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

1. We studied the origin of a low-speed solar wind using the solar wind speed measured by interplanetary scintillation (IPS), the soft X-ray solar corona data observed by the Yohkoh satellite, and photospheric magnetic field. We have found that the low-speed wind originated from over a sun spot region has a lower speed than that from the magnetic neutral line on the source surfase.2. We observed the phenomena of large acceleration in high-speed solar winds at distances of 0.1-0.3 AU using the IPS method. To confirm the reliability of the observational results, we estimated possible biasing effects in the observations by computer simulation. we have found that any biasing effects cannot cause the observational phenomena of the large acceleration.3. We studied the inner scale in micro turbulence using the IPS data observed at microfrequencies. The inner scale shows small but significant difference between a high-speed wind and a low-speed wind. This suggests that the inner scale is determined by cyclotron dumping. We also found that the behavior of the inner scale near the sun suggesting non-radial density divergence caused by solar wind acceleration.4. We studied the random velocity which is expected to be related to the MHD waves in the solar wind. We found that the radial distance dependence is obviously different between a high-speed wind and a low-speed wind : the high-speed wind shows increase of the random velocity at 0.1 AU,while the low-speed wind shows no radial distance dependency up to 0.1 AU.5. We made comparison of the solar wind speeds measured by the Ulysses and by the IPS.We found that if the turbulence level of density is proportional inversely to the root square of a speed, the IPS speeds agree with the Ulysses observations.

1. 我们利用行星际闪烁（IPS）测量的太阳风速、Yokkoh卫星观测到的软X射线日冕数据以及光球磁场，研究了低速太阳风的起源。我们发现，源自太阳黑子区域的低速风的速度比源自源面磁中性线的低速风低。2．我们利用IPS方法在0.1-0.3天文单位距离处观察到了高速太阳风的大加速度现象。为了确认观测结果的可靠性，我们通过计算机模拟估计了观测中可能存在的偏差影响。我们发现任何偏置效应都不会引起大加速度的观测现象。 3．我们使用在微频率下观察到的 IPS 数据研究了微湍流的内部尺度。内部尺度显示高速风和低速风之间虽小但显着的差异。这表明内部尺度是由回旋加速器倾倒决定的。我们还发现太阳附近内尺度的行为表明太阳风加速引起的非径向密度发散。4．我们研究了预计与太阳风中的 MHD 波相关的随机速度。我们发现高速风和低速风之间的径向距离依赖性明显不同：高速风在0.1 AU处表现出随机速度的增加，而低速风则没有表现出径向距离依赖性。至 0.1 AU.5。我们对Ulysses和IPS测量的太阳风速度进行了比较。我们发现，如果密度的湍流水平与速度的平方根成反比，则IPS速度与Ulysses的观测结果一致。