SIMBAD references

A spectral survey of IRC +10216 has been carried out in the range 11-14 µm with a spectral resolution of about 4 km/s. We have identified a forest of lines in six bands of C₂H₂ involving the vibrational states from the ground to 3ν₅ and in two bands of HCN, involving the vibrational states from the ground up to 2ν₂. Some of these transitions are observed also in H¹³CCH and H¹³CN. We have estimated the kinetic, vibrational, and rotational temperatures and the abundances and column densities of C₂H₂ and HCN between 1R_* and 300R_*(≃1.5x10¹⁶ cm) by fitting about 300 of these rovibrational lines. The envelope can be divided into three regions with approximate boundaries at 0.019" (the stellar photosphere), 0.1" (the inner dust formation zone), and 0.4" (outer dust formation zone). Most of the lines might require a large microturbulence broadening. The derived abundances of C₂H₂ and HCN increase by factors of 10 and 4, respectively, from the innermost envelope outward. The derived column densities for both C₂H₂ and HCN are ≃1.6x10¹⁹/cm2. Vibrational states up to 3000 K above ground are populated, suggesting pumping by near-infrared radiation from the star and innermost envelope. Low rotational levels can be considered under LTE, while those with J>20-30 are not thermalized. A few lines require special analysis to deal with effects like overlap with lines of other molecules.