Astronomy and Astrophysics – Astronomy
Scientific paper
Feb 1979
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1979a%26a....72..215w&link_type=abstract
Astronomy and Astrophysics, vol. 72, no. 1-2, Feb. 1979, p. 215-223.
Astronomy and Astrophysics
Astronomy
38
Absorption Spectra, Ammonia, Electron Transitions, Radio Astronomy, Galactic Nuclei, H Ii Regions, Line Spectra, Metastable State, Sagittarius Constellation
Scientific paper
The metastable (J, K) (1, 1), (2, 2), (3, 3), and (4, 4) inversion transitions and the nonmetastable (2, 1) and (3, 2) inversion transitions of ammonia have been observed in the direction of the Sgr B2 molecular cloud. The metastable lines are observed in absorption in the direction of the compact H II regions embedded in the cloud but in emission away from these positions. The nonmetastable lines are always observed in emission. Rotational temperatures of 65 to 180 K between the (2, 2) and (4, 4) levels are estimated and shown to be high in comparison with previous estimates of the cloud kinetic temperature based on CO measurements (about 20 K). It is argued that the kinetic temperature in the cloud core may be as high as 100 K. In addition, it appears that the nonmetastable transitions may be inverted and that the metastable transitions have excitation temperatures much lower than presently available statistical-equilibrium calculations predict. Possible explanations for this are discussed.
Churchwell Edward
Walmsley Charles Malcolm
Winnewisser Gisbert
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