HCNH+ abundance in cold dense clouds

Although it plays a crucial role in the chemistry of HCN and HNC, the excitation rate coefficients of this molecular cation by the dominant interstellar colliders have not been thoroughly investigated, leading to limitations in radiative transfer models use to derive its abundance.

We present here the first hyperfine-resolved excitation rate coefficients for HCNH^+^ induced by collisions with both He and H_2_ at low temperatures, addressing a crucial requirement for precise modeling of HCNH^+^ abundance in typical cold dense molecular clouds. Using non-local thermodynamic equilibrium (LTE) radiative transfer calculations, we reproduce fairly well the 1-->0 and 2-->1 observational spectra of HCNH^+^ and derive updated molecular column densities.