US-France Cooperative Research: A Study of Magnetic Fields in Interstellar Material

该奖项将支持托马斯·特罗兰博士与肯塔基大学的理查德·克鲁彻博士以及法国梅顿天文台的伊利亚·卡泽斯博士在天文学方面的合作研究。今天银河系天文学最引人注目的问题之一是星际物质云聚集在一起，形成新的恒星，然后最终消散的过程。理论研究表明，磁场可能在这一进化过程中发挥关键作用。然而，在星际介质中，特别是在分子云中，磁场强度是所有相关物理量中最不确定的。在过去的几年里，特罗兰博士和克鲁彻博士发起了一项重大的观测计划，以纠正这一缺陷。他们对18厘米OH谱线中塞曼效应的研究已经得到了目前存在的关于分子云场强的大部分信息。这些研究中的大多数都是利用南开射电望远镜进行的，该望远镜现在非常有效地实现了这一目的。他们寻求在南开继续这项工作，这将补充NRAO 43米望远镜和阿雷西博望远镜正在进行的塞曼效应观测。在所有地点收集的数据将允许对目前关于星际介质中磁效应的理论进行重要的实验测试。研究人员还计划开始另一个项目，用IRAM 30米望远镜观测毫米波长的塞曼效应。此外，用IRAM望远镜进行的额外观测将构成对塞曼效应区域密度研究的一部分。这项拟议工作的结果可能对我们理解分子云和其中的恒星形成过程有很大帮助。

This award will support collaborative research in astronomy between Dr. Thomas Troland, together with Dr. Richard Crutcher, University of Kentucky, and Dr. Ilya Kazes, Observatoire de Meudon, France. One of the most compelling problems of galactic astronomy today is the process whereby clouds of interstellar material gather together, form new stars and eventually disperse. Theoretical studies indicate that magnetic fields may play a crucial role in this evolutionary process. Yet magnetic field strengths are the least well determined of all relevant physical quantities in the interstellar medium, especially in molecular clouds. In the past few years, Drs. Troland and Crutcher have launched a major observational program to correct this deficiency. Their studies of the Zeeman effect in 18 centimeter OH lines have yielded most of the information that now exists regarding field strengths in molecular clouds. Most of these studies have been carried out with the Nancay radio telescope, which now functions very efficiently for this purpose. They seek to continue this work at Nancay, which will complement Zeeman effect observations in progress with the NRAO 43 meter telescope and the Arecibo telescope. Data collected at all sites will permit significant experimental tests of current theories on magnetic effects in the interstellar medium. The investigators also plan to begin work on another project, millimeter wavelength Zeeman effect observations with the IRAM 30 meter telescope. Moreover, additional observations made with the IRAM telescope will form part of a study of densities in regions searched for the Zeeman effect. The results of this proposed work may contribute significantly to our understanding of molecular clouds and of the star-forming processes within them.