Plasma Turbulence in the Interstellar Medium: Characteristics and Consequences

爱荷华大学的史蒂文·斯潘格勒博士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。研究计划中的研究方法包括：(1)使用通过HII区观察的河外射电源甚大阵列(VLA)进行新的射电天文观测；(2)利用VLA和Murchison Widefield阵列在附近脉冲星的低频进行新的观测；以及(3)检查和重新分析对附近星际云中湍流的广泛光谱测量。将在赠款期间进行的具体研究项目如下：(1)将利用VLA对通过6个HII区观看的约150个河外射电源及其相关气泡进行法拉第旋转观测；(2)将对四颗弱散射的脉冲星进行低频(小于100 MHz)的闪烁测量：将检查闪烁数据中是否存在“脉冲星弧”，其中包含关于湍流沿视线的距离和分布的信息；(3)将分析现有的一套由附近星际云引起的高质量的吸收线测量，以获取有关这些云中湍流特性的信息；(4)将研究轻电离分子云中的湍流特性及其与分子离子的相互作用。这项研究将通过对青年科学家进行个人化的物理科学研究方法、射电天文和放射物理测量能力以及等离子体物理基础方面的培训，使整个社会受益。斯潘格勒博士对爱荷华大学本科生和研究生的指导将在该奖项下继续下去。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团体，特别是爱荷华州锡达拉皮兹的雪松业余天文学家协会。

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.