Query : 2007A&A...470..615P

2007A&A...470..615P - Astronomy and Astrophysics, volume 470, 615-623 (2007/8-1)

Photon-dominated region modeling of the CO and [CI] line emission in Barnard 68.


Abstract (from CDS):

We use the Barnard 68 dark globule as a test case for a spherically symmetric PDR model exposed to low-UV radiation fields. With a roughly spherical morphology and an accurately determined density profile, Barnard 68 is ideal for this purpose. The processes governing the energy balance in the cloud surface are studied in detail. We compare the spherically symmetric PDR model by Stoerzer, Stutzki & Sternberg (1996A&A...310..592S) to observations of the three lowest rotational transitions of 12CO, 13CO J=2-1, and J=3-2, as well as the [CI] 3P1-3P0 fine structure transition. We study the role of polycyclic aromatic hydrocarbons (PAHs) in the chemical network of the PDR model and consider the impact of depletion, as well as of a variation in the external FUV field. We find it difficult to simultaneously model the observed 12CO and 13CO emission. The 12CO and [CI] emission can be explained by a PDR model with an external FUV field of 1-0.75χ0, but this model fails to reproduce the observed 13CO by a factor of ∼2. Adding PAHs to the chemical network increases the [CI] emission by 50% in our model but makes [CII] very faint. The CO depletion only slightly reduces the 12CO and 13CO line intensity (by ≲10% and ≲20%, respectively). Predictions for the [CI] 2P3/2-2P1/2, [CI] 3P2-3P1, and 12CO J=5-4 and 4-3 transitions are presented. This allows a test of our model with future observations (APEX, NANTEN2, HERSCHEL, SOFIA).

Abstract Copyright:

Journal keyword(s): astrochemistry - ISM: molecules - ISM: individual objects: Barnard 68 - ISM: clouds

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 829 0
2 NAME Ophiuchus Molecular Cloud SFR 16 28 06 -24 32.5           ~ 3497 1
3 LDN 57 DNe 17 22 38.2 -23 49 34           ~ 306 1

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