The circumstellar envelope of W3(OH) - NH3 observations

Abstract

Observations of absorption in the 1.3 cm (J,K) = (1,1) amd (2,2) lines of NH3 toward the ultracompact H II region W3(OH) made at subarcsecond resolution with the VLA are reported. Maps of optical depth, beam-filling factor, column density, and rotational temperature are presented. The NH3 absorption is similar to the OH maser emission in velocity, extent, and location, a result which suggests that both species are constituents of the same clumpy molecular envelope. The optical depths are nearly constant across the maps, while the beam-filling factors and the (2,2)-(1,1) rotational temperature decrease from west to east. The NH3 maps and the OH maser results indicate that the thermal and turbulent pressures in the ultracompact H II region are comparable to the magnetic and ram pressures from the surrounding neutral material that appears to be falling inward. 27 references.