Studies of Solar Wind and Coronal Turbulence via Radioastronomical Observations

研究人员将使用射电天文仪器和技术研究外日冕和内太阳风的等离子体。这些仪器是位于新墨西哥州中部的甚大阵列射电望远镜和分布在美国各地的甚长基线阵列射电望远镜。这两台仪器都是国家射电天文台的设施。该研究方案利用观测视线靠近太阳的河外射电源，从而探测距离为太阳半径4至35倍的日冕和太阳风。该研究将利用两种类型的测量，这些测量在过去的实验中已被证明是成功的：（1）法拉第旋转测量，以及（2）测量VLBA干涉仪相位中湍流引起的波动。该研究计划的科学目标包括：（1）绘制日冕法拉第旋转与扩展的极化背景射电源的关系图，以测量或限制全球日冕磁场和日冕湍流;（2）通过观测相对于太阳不同距离和方向的河外射电源星座，对日光层内的湍流进行层析成像;（3）利用磁流体动力学（MHD）模拟观测时的太阳风，阐明沿着视线的物理特性，分别确定高速和低速太阳风湍流条件;（4）研究引起相位闪烁现象的惯性范围等离子体湍流的各向异性，（5）继续进行一项计划，以遥控确定湍流密度波动强度与日心距的关系。这项研究计划的长期目标是确定日光层内部湍流的强度和等离子体物理特性，以便更好地评估这种湍流在日冕和太阳风动力学中的作用。此外，这项研究与星际介质的研究密切相关，包括与超新星遗迹有关的宇宙射线起源的研究。

The investigators will study the plasma of the outer solar corona and inner solar wind using radioastronomical instrumentation and techniques. The instruments are the Very Large Array (VLA) radiotelescope in central New Mexico, and the Very Long Baseline Array (VLBA) array of radiotelescopes distributed throughout the United States. Both instruments are facilities of the National Radio Astronomy Observatory. The research program utilizes observations of extragalactic radio sources whose lines of sight pass close to the Sun, and thus probe the corona and solar wind at distances from 4 to 35 times the solar radius. The study will make use of two types of measurements, which have proven successful in past experiments: (1) Faraday rotation measurements, and (2) measurement of turbulence-induced fluctuations in the phases of the VLBA interferometer. Among the scientific goals of the research program are (1) mapping of the coronal Faraday rotation against an extended, polarized, background radio source, to measure or constrain the global coronal magnetic field and coronal turbulence, (2) tomography of the turbulence in the inner heliosphere by observations of a constellation of extragalactic radio sources at different distances and orientations relative to the Sun, (3) the use of magnetohydrodynamic (MHD) simulations of the solar wind at the time of the observations to illuminate the physical characteristics along the lines of sight, and separately determine high speed and low speed solar wind turbulence conditions, (4) study of the anisotropy of the inertial range plasma turbulence responsible for the phase scintillation phenomena, and (5) continuation of a program to remotely determine the heliocentric distance dependence of the intensity of turbulent density fluctuations. The long-term goal of this program of research is to determine the intensity and plasma physical properties of turbulence in the inner heliosphere, so as to better assess the role this turbulence plays in coronal and solar wind dynamics. In addition, this research is closely related to that of the interstellar medium, including the study of the origin of the cosmic rays associated with supernova remnants.