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

TL;DR

This paper presents a detailed spectral line survey of the carbon-rich star IRC +10216 in the 13.3 to 18.5 GHz range, detecting 35 lines from 12 molecules, revealing its rich carbon chemistry.

Contribution

First spectral survey in this frequency range for IRC +10216, identifying multiple carbon-chain molecules and deriving their physical properties.

Findings

Detected 35 spectral lines from 12 molecules.

Confirmed rich carbon chemistry in IRC +10216.

Derived excitation temperatures and column densities.

Abstract

A spectral line survey of IRC +10216 between 13.3 and 18.5 GHz is carried out using the Shanghai Tian Ma 65 m Radio Telescope (TMRT-65m) with a sensitivity of < 7 mK. Thirty-five spectral lines of 12 different molecules and radicals are 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 AGB star. The excitation temperatures and column densities of the observed species are derived by assuming a local thermodynamic equilibrium and homogeneous conditions.