Table C.1
Critical densities for the upper levels involved in the observed transitions of C2H, ortho-c-C3H2 and HC3N. Critical densities of HCN were added for discussion purposes (see Sect. 5.1).
| Species | Upper level | Critical density (cm −3) | ||
|---|---|---|---|---|
| 5K | 10 K | 20 K | ||
| C2H | 11.5,1 | – | 3.46 × 104 | 1.97 × 104 |
| 11.5,2 | – | 3.73 × 104 | 2.07 × 104 | |
| 10.5,1 | – | 2.86 × 104 | 1.74 × 104 | |
| 10.5,0 | – | 2.55 × 104 | 1.64 × 104 | |
| ortho-c-C3H2 | 21,2 | 8.90 × 104 | 6.74 × 104 | 5.46 × 104 |
| 31,2 | 2.17 × 105 | 1.87 × 105 | 1.66 × 105 | |
| 41,4 | 4.82 × 105 | 4.15 × 105 | 3.66 × 105 | |
| HC3N | 8 | 6.55 × 104 | 5.64 × 104 | 4.53 × 104 |
| 9 | 9.20 × 104 | 8.06 × 104 | 6.51 × 104 | |
| 10 | 1.26 × 105 | 1.11 × 105 | 9.01 × 104 | |
| 11 | 1.63 × 105 | 1.47 × 105 | 1.20 × 105 | |
| 12 | 2.11 × 105 | 1.91 × 105 | 1.57 × 105 | |
| HCN | 1 | 6.35 × 105 | 4.81 × 105 | 2.71 × 105 |
| 2 | 6.20 × 106 | 4.31 × 106 | 2.30 × 106 | |
| 3 | 1.83 × 107 | 1.27 × 107 | 7.14 × 106 | |
| 4 | 3.35 × 107 | 2.57 × 107 | 1.60 × 107 | |
Notes. Spectroscopic and collisional data are taken respectively from the CDMS (Müller et al. 2005) and EMAA databases. For C2H, no collisional rates were available at 5 K.
References. Collisional data for C2H (Pirlot Jankowiak et al. 2023), c-C3H2 (Ben Khalifa et al. 2019), HC3N (Hily-Blant et al. 2018), and HCN (Hernández Vera et al. 2017).
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