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- L. Pagani, J. R. Pardo, A.J. Apponi and A. Bacmann.
"L183 Revisited-III : the gas depletion"
Astronomy and Astrophysics, 429, 181-192 (2005).
We present a detailed study of the gas depletion in
L183 (= L134N) for a set of
important species, namely, CO, CS, SO, N2H+ and NH3. 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 ~ 3 * 10**4 cm**(-3), while
N2H+b and NH3 seem to deplete at densities close to
10**6 cm**(-3). The latter result is consistent with the
Bergin and Langer (ApJ, 486, 316) polar (H2O) ice
case but not with the more recent models of Aikawa et al.
(ApJ, 593, 906). CS depletion occurs much below its
(J:2-1)b critical density, (7*10**5 cm**(-3) and
therefore makes this species unsuitable to study
the density structure of many
dark cloud cores.
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