AMMONIA IN THE W3(OH) REGION

Maps in the (J, K) = (1, 1) and (2, 2) inversion lines of NH3 made with 3'' angular resolution (=0.03 pc at 2.2 kpc) show the presence of optically thick unresolved emission 5.2'' east of the compact H II region W3(OH). The position agrees with previous HCN results. This clump is about 0.8'' west of the center of the group of H2O masers; the virial mass is 18 M.. From the virial mass and estimated radius, 0.006 pc, the average density is 4 x 10(8) cm-3. From the peak H-2 column density, 10(25) Cm-2, and the NH3 column density, 10(17) cm(-2), the NH3/H2 ratio is 10(-8). As found previously, there is prominent absorption toward the high surface brightness, compact H II region W3(OH). However, toward W3(OH), there is no emission counterpart to the NH3 absorption. There are weak, extended emission features more than 15'' SE and SW of W3(OH). This emission is not found to the north of W3(OH). This asymmetrically distributed emission would seem to provide an argument against a toroidal belt of molecular gas surrounding W3(OH). The largest scale feature is a remarkable, 1.5' long, less than 20'' wide filament which extends from N of the H II region-H2O maser complex to the NE. Within this filament there are at least five maxima. The T(k) in this region is of order 20-30 K, and the FWHP line width is less than 2.4 km s-1. From virial estimates, the molecular mass In our map is less than 200 M..