COMPACT AMMONIA SOURCES TOWARD THE G10.5-II REGION COMPLEX(0.0 H)

We present observations of the (2, 2) and (3, 3) inversion transitions of ammonia toward a group of compact H II regions near l = 10-degrees .5, b = 0-degrees.0, made at 4'' resolution using the VLA. We detected three distinct ammonia sources in a region of approximately 2' in dia meter. The densest and hottest cloud, having a line center velocity of 66.9 +/- 0.2 km s-1, is associated with the G 10.47 + 0.03 cluster of ultracompact H II regions. It exhibits a core-halo structure, with a core of approximately 0.08 pc in size surrounded by an envelope of app roximately 0.25 pc in diameter. The peak optical depth in the main lin e of the (2, 2) and (3, 3) transitions are 25 and 37, respectively. Th e rotational temperature of the ammonia gas rises from -25 K in the ou ter parts of the halo to -75 K at the center of the core. The ammonia column density rises from approximately 4 x 10(17) cm-2 in the envelop e region to approximately 4 x 10(18) cm-2 in the central position. The NH3 emission from the core region is remarkably broad in velocity; th e line widths of the (2, 2) and (3, 3) main lines are 12.2 +/- 1.2 and 11.6 +/- 0.5 km s-1, respectively. The observed velocity structure of the ammonia emission indicates that the halo is slowly rotating, with an angular velocity of 9.5 +/- 1.1 km s-1 pc-1, while the gas in the core is undergoing rapid motions. A second cloud, having an angular si ze of approximately 13', a line center velocity of 71.3 +/- 0.2 km s-1 , and a line width of 3.5 km s-1, is found toward the G10.46 + 0.03 co mplex region of ionized gas. It has a rotational temperature of 48 +/- 6 K and an NH3 column density of approximately 1 X 10(16) cm-2. The v elocity structure of the ammonia emission suggests that this cloud is probably expanding, with a velocity of approximately 2 km s-1. The thi rd cloud, at l = 10-degrees-48, b = 0.03-degrees, has a size of approx imately 9'', a line center velocity of 65.4 +/- 0.9 km s-1, and a line width of 3.5 km s-1, and is not associated with any known radio conti nuum emission. It may represent a molecular core undergoing gravitatio nal collapse in a stage prior to the formation of a star.