First detection of circular polarization in 4.7 GHz excited OH masers

Abstract

We report the first detection of circular polarization in 4.7 GHz excited OH masers in star-forming regions made using full Stokes measurements with the Green Bank 100m telescope. The Zeeman shift between the two circular components provides a measure of the magnetic field pervading these maser spots. Three different methods are used to determine the shift in velocity between the Right Circular Polarization and Left Circular Polarization components. We find fields with $B\sim 100$ mG using archival molecular parameters that have limited precision and uncertain values. Reservations of using 1.7 and 6.0 GHz OH masers to estimate magnetic fields in star-forming regions are discussed.

16 pages, 6 figures, 4 tables, accepted for publication in The Astrophysical Journal

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