KINETIC TEMPERATURES IN GALACTIC-CENTER MOLECULAR CLOUDS

Measurements of six metastable (J = K) inversion transitions of ammoni a for 36 clouds in the galactic center region are presented. Most of t he clouds are not related to SgrA or SgrB2. In order to minimize the e ffect of weather, either the (J, K)=(1, 1), (2,2) and (4,4) or the (4, 4) and (5,5) inversion lines of para-NH3 were measured simultaneously. A common calibration was obtained by forcing the integrated intensiti es of the (4,4) inversion line spectra from different periods to agree . The (3,3) and (6,6) lines of ortho-NH3 were also measured simultaneo usly. A determination of the rotational temperatures, T(rot), obtained from these lines shows that there must be at least two kinetic temper ature regimes in these clouds. In a few cases, small maps of the cloud s were made: two of these show that the distribution of the (1, 1) and (2,2) inversion lines are similar, but differ markedly from that of t he (4,4) inversion line. An analysis of the data shows that the warmer temperature is approximately 200 K, the cooler is approximately 25 K. The warmer gas contains about approximately 25% of the total column d ensity of NH3. The heating processes which give rise to the high kinet ic temperatures in these clouds are not certain: These may include an enhanced flux of low energy cosmic rays, cloud-cloud collisions, or io n-slip (ambipolar diffusion).