Plasma Turbulence in the Interstellar Medium: Characteristics and Consequences

史蒂文·斯潘格勒博士（爱荷华州大学）将探索星际介质中的湍流以及这种湍流在星际过程中所起的作用。 研究计划中的调查方法包括：（1）通过HII区域观察使用河外射电源的甚大阵列（VLA）进行新的射电天文观测，（2）使用VLA和Murchison Widefield Array在低无线电频率下对附近恒星进行新的观测，以及（3）检查和重新分析附近星际云湍流的广泛光谱测量。 在资助期内将进行的具体研究项目如下：（1）将用VLA对通过6个HII区域及其相关气泡观察的约150个河外射电源的样本进行法拉第旋转观测;（2）低频（小于100 MHz）闪烁测量将由四个微弱散射并通过“局部气泡”观察的散射体进行：将对闪烁数据进行检查，以确定是否存在“脉冲星弧”，脉冲星弧包含关于湍流沿着视线的距离和分布的信息;（3）将分析现有的一套高质量的邻近星际云吸收线测量数据，以确定其中包含的关于这些云中湍流特性的信息;（4）研究轻电离分子云中湍流的性质及其与分子离子的相互作用，通过对青年科学家进行物理科学研究方法、射电天文和射电物理测量能力以及等离子体物理基础等方面的个性化培训，使整个社会受益。 斯潘格勒博士对爱荷华州大学本科生和研究生的指导将继续在这个奖项下。 这项研究计划还有一个推广部分，包括与爱荷华州的业余天文学团体，特别是爱荷华州锡达拉皮兹的锡达业余天文学家的联系。

Dr. Steven Spangler (University of Iowa) will explore turbulence in the interstellar medium and the role such turbulence plays in interstellar processes. Methods of inquiry in the research program include (1) new radio-astronomical observations using the Very Large Array (VLA) of extragalactic radio sources viewed through HII regions, (2) new observations at low radio frequencies of nearby pulsars with the VLA and the Murchison Widefield Array, and (3) examination and re-analysis of extensive spectroscopic measurements of turbulence in nearby interstellar clouds. Specific research projects to be undertaken in the grant period are the following: (1) Faraday rotation observations will be made with the VLA of a sample of about 150 extragalactic radio sources viewed through 6 HII regions and their associated bubbles; (2) low frequency (less than 100 MHz) scintillation measurements will be made of four pulsars which are weakly scattered and viewed through the "Local Bubble": the scintillation data will be examined for the presence of "pulsar arcs", which contain information on the distance and distribution of turbulence along the line of sight; (3) an existing, high quality set of measurements of absorption lines due to nearby interstellar clouds will be analysed for the information it contains on the properties of turbulence in these clouds; (4) the properties of turbulence in the lightly ionized molecular clouds, and its interaction with molecular ions, will both be investigated.This research will benefit society as a whole through the individualized training of young scientists in the methods of physical science research, the capabilities of radioastronomical and radiophysical measurements, and in fundamentals of plasma physics. Dr. Spangler's mentorship of University of Iowa undergraduate and graduate students will continue under this award. This research program also has an outreach component, consisting of an association with amateur astronomy groups in Iowa, particularly the Cedar Amateur Astronomers in Cedar Rapids, Iowa.