Measurement of Magnetic Field Strength in the Dark Cloud Barnard 1

The detection of the Zeeman effect in OH emission in the dark cloud Barnard 1 is reported. The region of the OH emission in B1 extends over 1.1 pc, has 1.3 km/s linewidth, and has mean column density of 6 x 10 to the 21st/sq cm. The detected field strength, -27 + or - 4 micro-G, agrees well with two estimates of equilibrium field strength derived from the observations, and also with the evolutionary model of Mouschovias (1976, 1987). 31 references.