The Role of Magnetic Fields in the Evolution of Molecular Clouds

理论研究已经提供了令人信服的论据，即磁场在星际介质中由物质云形成恒星的过程中发挥着重要的、或许是必不可少的作用。对这些理论结果的实证检验非常重要。可能的测试是：(1)通过观测中性原子氢原子、羟基和其他分子的谱线上的塞曼效应来测量和绘制稠密云中的磁场强度；(2)通过观测和绘制选定分子的毫米波谱线来确定云的质量、大小、运动学和密度，以评估磁场的动力学重要性；(3)测量云中分子物种的分数电离变化，以估计冻结磁场通量的条件；(4)测定质量磁通量比及其在云中的变化。这笔赠款支持伊利诺伊大学理查德·克鲁彻博士与肯塔基大学托马斯·特罗兰博士合作开展的一个观察性研究项目，以测试上述所有领域的当前理论想法。

Theoretical research has provided compelling arguments that magnetic fields play an important and perhaps essential role in the formation of stars out of clouds of material in the interstellar medium. Empirical tests of these theoretical results are very important. Possible tests are: (1) the measurement and mapping of the strengths of the magnetic fields in dense clouds by observations of the Zeeman effect on spectral lines of neutral atomic hydrogen, hydroxyl, and other molecules; (2) determination of cloud masses, sizes, kinematics, and densities by observation and mapping of millimeter-wave lines of selected molecules in order to assess the dynamical importance of magnetic fields; (3) measurement of the variation of the fractional ionization of molecular species in clouds in order to estimate the conditions for freezing the magnetic field flux; and (4) determination of the mass-to-magnetic flux ratio and its variation within a cloud. This grant supports an observational research project conducted by Dr. Richard Crutcher, at the University of Illinois, in collaboration with Dr. Thomas Troland, at the University of Kentucky, to test the current theoretical ideas in all of the areas outlined above.