Zeeman splitting of 18 centimeter OH lines toward Cassiopeia A and other sources

Abstract

Zeeman splitting of the OH absorption lines has been detected toward Ori B, W22, and Cas A. For W22, the derived magnetic field strength is -11 micro-G. For Ori B, the inferred magnetic field strength is consistent in magnitude, but not in direction, with the 38 micro-G derived previously by Crutcher and Kazes (1983, 1985); the field is positive and therefore points away from the observer. For Cas A, the average field in four velocity components is +9 micro-G, in the same direction as, but weaker than, the field strengths measured in single-dish H I data. They are considerably weaker than the field strengths in less dense H I clumps that are associated with the OH clumps. This circumstance raises serious interpretive difficulties.