Ammonia in the W3(OH) region

High-sensitivity 3 arcsec angular resolution maps have been made in the (J,K) = (1,1) and (2,2) inversion lines of NH3 over a 2 arcmin region centered on the compact H II region W9(OH). There is no emission one beam north of the region, and a beam-averaged upper limit of 10 exp 14/q cm can be set for this gas. One beam south of W3(OH), the column density is 2 x 10 exp 14/sq cm. These values are 1/30 of those seen in absorption, a lack of emission which indicates that the model involving a symmetrical toroid of molecular gas around W3(OH) needs some revision. The symmetric elliptical shape of the H II region cannot be explained in a simple model involving champagne flow since molecular clouds are found only to the south. Toward the H2O masers, there is an unresolved center of optically thick NH3 emission. Excitation arguments indicate that the radius is 0.04 pc. Applying the virial theorem to the line width shows a mass of 18 solar masses and an average density of 10 exp 9/cu cm.