Kinematics, kinetic temperatures, and column densities of NH3 in the OrionHot Core

Using the VLA, we have mapped the Orion Hot Core region (full extent 10 ") with an angular resolution of similar to 1 " in the (J, K)=(4,4) and (10, 9 ) inversion transitions of (NH3)-N-14 and an angular resolution of 4 " in t he (J, K) = (2, 2) and (3, 3) inversion transitions of (NH3)-N-15. All of t he single-dish flux density for the (10, 9) transition was recovered by the VLA, but a substantial fraction of the flux density in the (4, 4) and (NH3 )-N-15 (3, 3) lines was not detected. The missing flux density is from the spatially extended "spike" component. Assuming that local thermodynamic equ ilibrium (LTE) holds, we have calculated the optical depths of the (4, 4) i nversion transition for all positions where the main and satellite lines we re detected with sufficient signal-to-noise ratio. We combined our (10, 9) data with these (4, 4) line results to produce images of the rotational tem perature, T-rot, and the column density of ammonia, N(NH3). For the H-2 den sities in the Hot Core, T-rot = T-kin, the kinetic temperature. An addition al determination of T-kin and N(NH3) was made by combining our (10, 9) inve rsion line data with our (NH3)-N-15 (3, 3) inversion line results. The (NH3 )-N-15 inversion transitions have no quadrupole hyperfine structure so that the line shapes are simpler. The moment distribution of the (NH3)-N-15 (3, 3) line shows that the largest intensity-weighted line width arises close to the center of the Hot Core region. Thus, we may have discovered a low-lu minosity outflow source embedded in the Hot Core. Alternatively, this may b e a result of gas motions related to source " I," which is about half a bea mwidth from this feature.