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

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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.