Extended Data Fig. 6: Possible detection of weak H2O lines in the 17.2 μm and 6.5 μm regions.
From: A rich hydrocarbon chemistry and high C to O ratio in the inner disk around a very low-mass star
The pure rotational lines at 16.5–18 μm can hide as much as N(H2O)=3 × 1018 cm−2 assuming a fixed temperature of 525 K and a characteristic emitting radius of R = 0.033au, corresponding to the optically thick C2H2 component I. These lines are not affected by masking of C2H2 since only very weak lines of C2H2 are present in these spectral ranges. Some lines in the 6.3-6.8 μm range are somewhat overestimated by our LTE model but non-LTE effects will tend to quench these lines compared to the pure rotational lines longward of ~ 12μm59.
