2009A&A...498..161V


C.D.S. - SIMBAD4 rel 1.7 - 2021.03.05CET21:17:01

2009A&A...498..161V - Astronomy and Astrophysics, volume 498, 161-165 (2009/4-4)

Chemical stratification in the Orion bar: JCMT spectral legacy survey observations.

VAN DER WIEL M.H.D., VAN DER TAK F.F.S., OSSENKOPF V., SPAANS M., ROBERTS H., FULLER G.A. and PLUME R.

Abstract (from CDS):

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'x2' fields at 14''-23'' resolution toward the Orion Bar in the SO 88-99, H2CO 515-414, 13CO 3-2, C2H 49/2-37/2 and 47/2-35/2, 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 the H2CO peak 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.

Abstract Copyright:

Journal keyword(s): ISM: molecules - ISM: structure - ISM: individual objects: Orion Bar - stars: formation

Errata: erratum vol.510, p. C1 (2010)

Simbad objects: 3

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Number of rows : 3

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 NAME Ori Region reg 05 35 17.30 -05 23 28.0           ~ 500 0
2 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 743 0
3 NAME ORI MOL CLOUD MoC 05 56 -01.8           ~ 890 1

    Equat.    Gal    SGal    Ecl

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