On the excitation of interstellar ammonia in the Kleinmann-Low nebula

摘要: We report investigations of the region in which NH/sub 3/ lines are formed direction Kleinmann-Low nebula. A non-LTE model, including transfer both line radiation and dust-generated continuum radiation, was constructed to study excitation lowest 31 levels 3/. Agreement between model observations is excellent. The implies relatively high densities (approx.10/sup 6/H/sub 2/cm/sup -3/) temperatures (approx.70K) for formation region. These results further imply that come from a small (approx.16'') core with an optical depth approx.0.02 dust at 250..mu..m. have also studied problem shapes. derive abundance (NH/sub 3/)/(H/sub 2/)approx. =5 x 10/sup -7/, factor approx.10/sup higher than ion-molecule predictions. Our is, however, consistent ice on grains seen toward BN object if interpretation 3..mu..m feature as H/sub 2/O ices correct. suggest extreme clumping implied by 16'' may be due evaporation