1995A&A...297..567T -
Astronomy and Astrophysics, volume 297, 567-573 (1995/5-2)
Atomic carbon and CO isotope emission in the vicinity of the Orion Bar.
TAUBER J.A., LIS D.C., KEENE J., SCHILKE P. and BUETTGENBACH T.H.
Abstract (from CDS):
We present observations of the 3P1-3P0 fine structure transition of atomic carbon, as well as of the J=2-1 transition of 13CO and C18O toward the Orion Bar, the south-eastern rim of the cavity carved out in the Orion molecular cloud by the HII region surrounding the Trapezium stars. The Orion Bar is a dense region illuminated by an intense flux of UV photons, i.e. a photodissociation or photon-dominated region (PDR). The observed Ci intensity agrees with models of uniform-density edge-on PDRs, which predict a spatially stratified morphology for the ionized, neutral, and molecular components. Our observations, however, show a surprisingly good spatial correlation between Ci and 13CO. The bright neutral carbon and 13CO emission from the Bar is superposed on a broad plateau of extended emission. The origin of this extended distribution may lie in the particular geometry of the region, which gives rise to face-on PDRs associated with the back and front walls of the cavity. Because of their weak emission, we infer that these face-on PDRs must be clumpy with a low beam filling factor (∼30-40%) in contrast to the Bar which has been shown to have a filling factor of ∼1 for radiation from the ionizing stars.
Abstract Copyright:
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Journal keyword(s):
ISM: atoms - ISM: clouds - ISM: individual objects: Orion - radio lines: ISM
Simbad objects:
6
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