SIMBAD references

We report the detection of a 3.1±0.4mG magnetic field in the dense crescent of gas bordering the W3(OH) compact HII region. The Zeeman splitting in the highly excited ²{PI}_3/2 J=7/2 F=3⁺-3^– transition of OH was observed, in absorption against the radio continuum, with the MPIfR 100-m telescope. The derived field strength is, by far, the strongest ever reported from thermally excited, i.e., non-masing gas; it compares with the average field derived from the cluster of OH maser spots, thought to arise from within the same dense layer of gas. A quantitative anlysis reveals that magnetic pressure dominates the clump energetics by nearly an order of magnitude over other processes. A possible scenario is discussed in terms of a bow-shock model, in which the magnetic field is compressed in the cooled post-shock layer preceeding the compact HII region.