L183 (L134N) revisited. III. The gas depletion

We present a detailed study of the gas depletion in L183 (= L134N) for a set of important species, namely, CO, CS, SO, N sub(2)H super(+) and NH sub(3). We show that all these species are depleted at some level. This level seems to depend mostly on a density threshold rather than on dust opacity. Th...

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Published in:Astronomy and astrophysics (Berlin) 2005, Vol.429 (1), p.181-192
Main Authors: PAGANI, L, PARDO, J.-R, APPONI, A. J, BACMANN, A, CABRIT, S
Format: Article
Language:English
Subjects:
Astrophysics
Sciences of the Universe
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Summary:We present a detailed study of the gas depletion in L183 (= L134N) for a set of important species, namely, CO, CS, SO, N sub(2)H super(+) and NH sub(3). We show that all these species are depleted at some level. This level seems to depend mostly on a density threshold rather than on dust opacity. Therefore UV shielding would not be a main factor in the triggering of depletion. Our data suggest that CO, CS and SO depletion happen at densities of similar to 3 x 10 super(4) cm super(-3), while N sub(2)H super(+) and NH sub(3) seem to deplete at densities close to 10 super(6) cm super(-3). The latter result is consistent with the Bergin & Langer (1997, ApJ, 486, 316) polar (H sub(2)O) ice case but not with the more recent models of Aikawa et al. (2003, ApJ, 593, 906). CS depletion occurs much below its (J:2-1) critical density, (7 x 10 super(5) cm super(-3)) and therefore makes this species unsuitable to study the density structure of many dark cloud cores.
ISSN:0004-6361
1432-0746
1432-0756
DOI:10.1051/0004-6361:20041044