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Fig. 2


Theoretical HC3N (9–8)/HC5N (31–30) line intensity ratio assuming LTE and optically thin conditions as a function of the gas temperature for different values of the HC3N/HC5N abundance ratio as marked (black curves). The range of values observed within a 2σ error bar towards the three regions listed in Table 1 are showed as dashed areas: FIR4-HC5N (blue), FIR4-lowHC5N (green) and FIR5 (red). We note that the temperature of FIR4 was estimated to be ~40 K (Ceccarelli et al. 2014) while no estimates for FIR5 exist.

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