AAS 198th Meeting, June 2001
Session 59. Galactic ISM
Display, Wednesday, June 6, 2001, 10:00am-7:00pm, Exhibit Hall

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[59.15] Circular Polarization in water masers - VLA Zeeman Effect Observations

A. P. Sarma (NCSA, University of Illinois at Urbana-Champaign), T. H. Troland (Physics & Astronomy Dept., University of Kentucky), R. M. Crutcher (Astronomy Dept., University of Illinois at Urbana-Champaign), D. A. Roberts (IT Dept., Northwestern University)

We present VLA observations of the Zeeman effect in water masers. The Zeeman effect in radio frequency spectral lines remains the most direct method for measuring magnetic field strengths in the ISM. Water masers are an unique tracer of the Zeeman effect in high density regions. Our observations, which constitute the first comprehensive interferometric study of the Zeeman effect in water masers, reveal significant fields ranging from 13 to 49 mG in several star forming regions. For some regions, the detected fields also provide a 2/3-point map of the magnetic field, indicating the nature of field variations on arcsecond scales. The observed values of the magnetic field indicate that the magnetic field-gas density relationship inferred from H I and OH Zeeman effect observations at lower densities may carry over to the higher density regime.

The author(s) of this abstract have provided an email address for comments about the abstract: asarma@astro.uiuc.edu

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