Studies of Solar Wind and Coronal Turbulence via Radioastronomical Observations

研究人员将利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。这些仪器是新墨西哥州中部的甚大阵列(VLA)射电望远镜，以及分布在美国各地的甚长基线阵列(VLBA)射电望远镜阵列。这两台仪器都是国家射电天文台的设施。该研究计划利用对视线靠近太阳的河外射电源的观测，从而探测距离太阳半径4到35倍的日冕和太阳风。这项研究将使用两种在过去的实验中被证明是成功的测量：(1)法拉第旋转测量，和(2)测量VLBA干涉仪中由湍流引起的相位波动。该研究计划的科学目标包括：(1)绘制针对扩展的、极化的背景射电源的日冕法拉第旋转图，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，对内日光层中的湍流进行层析成像；(3)使用观测时太阳风的磁流体动力学(MHD)模拟，以照亮视线上的物理特征，并分别确定高速和低速太阳风湍流条件，(4)研究引起位相闪烁现象的惯性范围内等离子体湍流的各向异性；(5)继续编制程序，遥测湍流密度起伏强度与日心距离的关系。这项研究计划的长期目标是确定日球层内湍流的强度和等离子体物理性质，以便更好地评估这种湍流在日冕和太阳风动力学中所起的作用。此外，这项研究与星际介质密切相关，包括研究与超新星遗迹相关的宇宙射线的起源。

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.