Table 3
Parameters of the chemical simulations.
| Simulation label | n(H2) (cm−3) | Tgas,·Tdust (K) | AV (mag) | Chemical network |
|---|---|---|---|---|
| S1 | 106 | 7, 7 | 30 | Full chemical network with C and N fractionation, and |
| spin-state chemistry | ||||
| S2 | 104 | 10, 10 | 10 | As in S1 |
| S2_3C | 104 | 10, 10 | 10 | Only carbon fractionation, no spin-state chemistry |
| S2_3C_alt | 104 | 10, 10 | 10 | As in S2_3C, but omitting the newly included C isotopic |
| exchange reactions displayed in Table 1 | ||||
| S2_C20 | 104 | 10, 10 | 10 | Chemical networks of C20 |
| S3 | 5 × 102 | 20, 15 | 1 | As in S1 |
| S3_ss | 5 × 102 | 20, 15 | 1 | As in S1, but with isotope-selective N2 and CO self-shielding(a) |
Notes. The cosmic ray ionization rate is fixed to ζ = 1.3 × 10−17 s−1 in all simulations. (a)The assumed values for the N2 and CO column densities are 1013 cm−2 and 9 × 1014 cm−2, respectively (see Sect. 4.2). N2 and CO self-shielding effects are neglected in all other simulations. H2 self-shielding is however taken into account in all simulations, with the column density calculated from the relation N(H2)/AV = 1021 cm−2 mag−1 and the self-shielding factor calculated following Draine & Bertoldi (1996, their Eq. (37)).
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