1982/08/01 by R. Genzel, Paul T. P. Ho, John H. Bieging +1 · 1 citation
Earth and Planetary Sciences · Physics and Astronomy · Chemistry · #Atmospheric Ozone and Climate #Astrophysics and Star Formation Studies #Spectroscopy and Laser Applications
paper · doi:10.1086/183856
openalex publication_date 1982/08/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/11
The observations of ammonia in Orion-KL are reinterpreted in a way which greatly simplifies the understanding of single-dish and VLA data. In this new picture, there are only two velocity components: the 'spike' component from the quiescent molecular cloud and the 'hot core' component from both streaming and 'stationary' gas in the 18 km/s outflow from the compact infrared source IRc2. What has been interpreted previously as the NH3 'plateau' from high-velocity gas is mainly the blended hyperfine satellite emission from the 'hot core' component. The ammonia lines are highly optically thick) tau greater than (10), and NH3 column densities reach 5 x 10 to the 18th per sq cm. Kinetic temperatures in the outflow region are bout 200 K, and NH3 is probably collisionally excited at hydrogen densities of 10 to the 8th to 10 to the 9th per cu cm. Ammonia may be highly overabundant in this dense and warm gas and may tie up a considerable fraction of the available nitrogen. The maps can be interpreted as showing a clumpy, expanding, and turbulent shell advancing into the densest part of the Orion-KL region.