Table 2.
Three-stage evolutionary cloud model.
| Stage 1 | Stage 2 | Stage 3 | |
|---|---|---|---|
| Classification (a) | Diffuse | Translucent | Dense |
| ngas (cm−3) | 1e2 | 1e3 | 104–106 |
| N(H2)ext. (cm−2) (b) | 5.7e20 | 5.7e20 | 3.1e21 |
| radius (pc) | 25 | 10 | 1 |
| AV (mag) | 0.5 | 1.6 | 10 |
| ζ (s−1) | 1.0e−16 (c) | 1.3e−17 | 1.3e−17 |
| Tgas (K) | 100 | 25 | 10 |
| Tdust (K) | 15 | 15 | 10 |
| Time (yr) (d) | 107 | 106 | 105–106 |
Notes.
Classification is based on Snow & McCall (2006); see text for details.
This the H2 column density external to our single-point calculations, whereby the total column density used for the shielding factor is the sum of the external and “internal” components; the component of external N(CO) is always set to a factor of 10−6 below that of the external N(H2), as per general agreement with observations (Snow & McCall 2006, and references therein).
Equivalent to that of Rho Oph (Indriolo & McCall 2012).
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