Testing Faraday Rotation Estimates of Magnetic Field Strengths toward Dark Clouds

Abstract

We have carried out OH Zeeman observations toward a position at the edge of a Taurus molecular cloud where a continuum polarization minimum and excessive Faraday rotation measure were reported by Wolleben & Reich in 2004. They had interpreted this result as requiring a line-of-sight magnetic field strength in excess of 20 μG. Our Zeeman measurement failed to detect a field consistent with this result.