A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz

A spectral line survey of IRC + 10216 between 13.3 and 18.5 GHz was carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65 m) with a sensitivity of <7 mK. Thirty-five spectral lines of 12 different molecules and radicals were detected in total. Except for SiS, the detected molecules are all carbon-chain molecules, including HC3N, HC5N, HC7N, HC9N, C6H, C6H, C8H, SiC2, SiC4, c-C3H2, and l-C5H. The presence of rich carbon-bearing molecules is consistent with the identity of IRC +10216 as a carbon-rich asymptotic giant branch (AGB) star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.