Table 1.
Summary of derived gas properties.
| Species | Wavelength | Componenta | N | Trot | fbg | Vrad | σV |
|---|---|---|---|---|---|---|---|
| μm | cm−2 | K | kms−1 | kms−1 | |||
| CO | 4.7 | c | 8×1017−2×1018 | 15−19 | 1−0.77 | +60 | ∼ 90 |
| CO | 4.7 | mw | 1.4×1018−2.3×1018 | 88−120 | 1−0.77 | −60 | ∼ 140 |
| CO | 4.7 | h | 9.5×1018−1.4×1019 | 730−690 | 1−0.77 | 0 | ∼ 190 |
| H2Ob | 6.2 | w | 2.4×1018−7.0×1018 | 300−270 | 1−0.35 | 0 | ∼ 90 |
| CH4 | 7.7 | w | 4.2×1018−4.7×1018 | 333−291 | 0.10−0.12c | 0 | ∼ 70 |
| C2H2d | 13.7 | mw (ν5) | 2.29±0.05e17 | 149±2 | 0.28±0.003e | −55 | ∼ 90 |
| C2H2 | 7.5 | mw (ν4+ν5) | 4.3×1017−2.6×1018 | 179−157 | 1−0.2 | 0 | ∼ 70 |
| HCN | 14.0 | c (ν2) | 2.45±0.11e17 | 52±2 | 0.28±0.003e | −75 | ∼ 90 |
| HCN | 14.0 | w (ν2) | 1.15±0.08e17 | 328±22 | 0.28±0.003e | −75 | ∼ 90 |
| HCN | 7.1 | mw (2ν2) | 5×1017−7×1018 | 110−130 | 1−0.1 | −15 | ∼ 75 |
| CO2 | 15.0 | c | 5.8×1015−2.6×1017 | 40−59 | 1−0.05 | −75 | ∼ 90 |
| N2H+ | 14.6 | c/mw | 1.3×1015−4.4×1016 | 132−192 | 1−0.05 | −75 | ∼ 90 |
| C2H | 5.4 | mw | 2.6×1017−3.7×1018 | 138−107 | 1−0.1 | −50 | ∼ 70 |
| NO | 5.3 | c | 1.3×1017−1.8×1018 | 60−48 | 1−0.1 | −50 | ∼ 70 |
| HNC | 21.6 | c | 3.2±1.2e16 | 38±4 | 0.06±0.02 | 0f | ∼ 90 |
| HCO+ | 12.1 | c? | ≲5e15 | ||||
| CS | 7.9 | ||||||
| HC3N | 15.1 | c? | ≲e16 | ||||
| HCNH+ | 12.5 | c? |
Notes. Background fractions were fit directly when constrained by optically thick features. In these cases, the uncertainties quoted are statistical 68% confidence intervals from the MCMC sampling, and do not reflect the larger systematic uncertainties. In all other cases, parameter ranges are given based on fits with the maximum and minimum possible background fraction. The radial velocities are either based on direct measurements of individual lines (e.g. CO, C2H2, HCN) or estimated from a visual comparison of the observed and modelled spectra (e.g. N2H+, CO2).
Cold (c), moderately warm (mw), warm (w) or hot (h); see Section 4.2.
The H2O ortho-to-para ratio inferred from several fits was consistent with the equilibrium value of 3; it was therefore fixed to this value in the final run.
An ortho-to-para ratio of 1.71±0.05 was inferred from the 13.7 μm band; it was fixed to this value in the 7.5 μm fit.
Coupled in the fit. If the warm HCN is located in a deeper layer of the region, its background fraction may be overestimated and, consequently, its actual column density could be higher than reported here.
With respect to the systemic redshift zWN = 0.01786 (Sakamoto et al. 2009).
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