Astronomy and Astrophysics – Astrophysics – Galaxy Astrophysics
Scientific paper
2009-02-09
Astronomy and Astrophysics
Astrophysics
Galaxy Astrophysics
Published in A&A 498, 161-165 (2009); v2: updated with correct line strengths after corrigendum in A&A 510, C1 (2010)
Scientific paper
10.1051/0004-6361/200811391
Photon-dominated regions (PDRs) are expected to show a layered structure in molecular abundances and emerging line emission, which is sensitive to the physical structure of the region as well as the UV radiation illuminating it. We aim to study this layering in the Orion Bar, a prototypical nearby PDR with a favorable edge-on geometry. We present new maps of 2 by 2 arcminute fields at 14-23 arcsecond resolution toward the Orion Bar in the SO 8_8-9_9, H2CO 5_(1,5)-4_(1,4), 13CO 3-2, C2H 4_(9/2)-3_(7/2) and 4_(7/2)-3_(5/2), C18O 2-1 and HCN 3-2 transitions. The data reveal a clear chemical stratification pattern. The C2H emission peaks close to the ionization front, followed by H2CO and SO, while C18O, HCN and 13CO peak deeper into the cloud. A simple PDR model reproduces the observed stratification, although the SO emission is predicted to peak much deeper into the cloud than observed while H2CO is predicted to peak closer to the ionization front than observed. In addition, the predicted SO abundance is higher than observed while the H2CO abundance is lower than observed. The discrepancies between the models and observations indicate that more sophisticated models, including production of H2CO through grain surface chemistry, are needed to quantitatively match the observations of this region.
der Tak Floris F. S. van
der Wiel Matthijs H. D. van
Fuller Gary A.
Ossenkopf Volker
Plume Rene
No associations
LandOfFree
Chemical stratification in the Orion Bar: JCMT Spectral Legacy Survey observations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Chemical stratification in the Orion Bar: JCMT Spectral Legacy Survey observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chemical stratification in the Orion Bar: JCMT Spectral Legacy Survey observations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-176520