HOT AMMONIA EMISSION - KINETIC TEMPERATURE-GRADIENTS IN ORION-KL

The first astronomical detections of the (J, K) = (10,10), (11,11), (1 2,12), (13,13) and (14,14) doublet inversion emission lines of NH3 at 1 cm wavelength are presented. These transitions are emitted from ener gy levels up to 1900K above the ground state; these are the most energ etic states probed by quasithermal radio emission lines. The linewidth s and radial velocities are consistent with emission from the Hot Core of the Orion KL nebula. There is no systematic change in DELTAV1/2 an d V(lsr) with (J, K). The spectra also show no wide linewings; these f indings agree with results for inversion transitions between lower lyi ng doublet levels. From a least squares fit to the column densities of the new NH3 inversion line data, T(rot) is similar to 400+/-40K; this exceeds the previous value based on lower lying NH3 inversion lines. A good fit to the 37 NH3 inversion lines is obtained using a model wit h spherical symmetry and all NH3 inversion lines thermalized. This giv es n(H-2) is similar to R-2.5+/-0.2, if T(k) is similar to R-0.4. Comp arisons are made with other Hot Core results.