Rotational Excitation of HC5NH+ by He: Collision Dynamics and Astrophysical Applications
Abstract
Reliable collisional rate coefficients are crucial for interpreting the rotational emission spectra of molecules in interstellar clouds. In this work, we construct a two-dimensional potential energy surface (PES) for the HC5NH+--He system at the CCSD(T)-F12B/cc-pVTZ-F12 level of theory. Rotationally inelastic cross sections are calculated using the quantum close-coupling (CC) method, and the corresponding collisional rate coefficients are obtained by thermal averaging over a Maxwell--Boltzmann distribution. We use these collisional data in a non-local thermodynamic equilibrium (non-LTE) radiative transfer model to investigate the excitation of HC5NH+ in the cold dark cloud TMC-1. A global χ2 minimization analysis of seven observed lines yields best-fitting values of n(H2)=1.63×105\,cm−3 and N(H2)=5.09×1011\,cm−2, with reduced χ2min=0.87. The modelled line intensities are in good agreement with the observations. These results provide insight into the collisional excitation and radiative properties of HC5NH+ under the physical conditions prevailing in TMC-1.
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BibTeX
@misc{xiang2026rotational,
title = {{Rotational Excitation of HC$_5$NH$^+$ by He: Collision Dynamics and Astrophysical Applications}},
author = {Ziyu Xiang and Liman Tian and Tong Sun and Wenli Zou and Xiaolin Chen},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.08197},
eprint = {2611.08197},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.08197},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Rotational Excitation of HC_5NH^+ by He: Collision Dynamics and Astrophysical Applications
AU - Ziyu Xiang
AU - Liman Tian
AU - Tong Sun
AU - Wenli Zou
AU - Xiaolin Chen
PY - 2026
DA - 2026/11/05
PB - arXiv
DO - 10.48550/arxiv.2611.08197
UR - https://arxiv.org/abs/2611.08197
AB - Reliable collisional rate coefficients are crucial for interpreting the rotational emission spectra of molecules in interstellar clouds. In this work, we construct a two-dimensional potential energy surface (PES) for the HC_5NH^+--He system at the CCSD(T)-F12B/cc-pVTZ-F12 level of theory. Rotationally inelastic cross sections are calculated using the quantum close-coupling (CC) method, and the corresponding collisional rate coefficients are obtained by thermal averaging over a Maxwell--Boltzmann distribution. We use these collisional data in a non-local thermodynamic equilibrium (non-LTE) radiative transfer model to investigate the excitation of HC_5NH^+ in the cold dark cloud TMC-1. A global χ^2 minimization analysis of seven observed lines yields best-fitting values of n(H_2)=1.63×10^5\,cm^−3 and N(H_2)=5.09×10^11\,cm^−2, with reduced χ^2_min=0.87. The modelled line intensities are in good agreement with the observations. These results provide insight into the collisional excitation and radiative properties of HC_5NH^+ under the physical conditions prevailing in TMC-1.
ER -