{
  "abstract": "Reliable collisional data are essential for interpreting the rotational emission of HMgC$_3$N under the non-equilibrium conditions of molecular clouds. We investigate the rotational excitation and de-excitation of HMgC$_3$N induced by collisions with He, combining \\textit{ab initio} calculations with quantum scattering theory. A two-dimensional potential energy surface (PES) for HMgC$_3$N--He was constructed using the CCSD(T)-F12A method in conjunction with the aug-cc-pVTZ basis set. Quantum close-coupling (CC) calculation were then performed to obtain state-to-state integral cross sections and temperature-dependent rate coefficients for rotational transitions with $Δj=\\pm1$, $\\pm2$, and $\\pm3$, covering rotational levels up to $j=20$ and temperatures from $3$ to $50$~K. The rate coefficients exhibit a clear propensity for $Δj=\\pm2$ transitions. The resulting collisional data were incorporated into radiative transfer modelling to constrain the physical conditions and column density of HMgC$_3$N from its observed spectral line emission. A $χ^2$ minimization yields a best-fitting H$_2$ volume density of $n(\\mathrm{H}_2)=1.233\\times10^5~\\mathrm{cm}^{-3}$ and column density of $N(\\mathrm{HMgC}_3\\mathrm{N})=1.831\\times10^{12}~\\mathrm{cm}^{-2}$. The derived column density is in approximate agreement with the observational estimate of $(3.0\\pm0.6)\\times10^{12}~\\mathrm{cm}^{-2}$. These results provide new collisional data for non-LTE studies of HMgC$_3$N and support a more realistic treatment of its rotational excitation and radiative transfer in molecular clouds.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.41876",
  "author_total": 4,
  "authors": [
    {
      "name": "Liman Tian"
    },
    {
      "name": "Ziyu Xiang"
    },
    {
      "name": "Wenli Zou"
    },
    {
      "name": "Xiaolin Chen"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/ca04nbhpxtdz1.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.41876",
  "fulltext_url": null,
  "id": "ca04nbhpxtdz1",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.41876",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.41876",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/ca04nbhpxtdz1.ris",
  "sources": [
    {
      "first_seen": "2026-11-02T12:21:15Z",
      "native_id": "2610.41876",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.41876"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "Collisional excitation of HMgC$_3$N by He: rate coefficients and astrophysical implications",
  "title_text": "Collisional excitation of HMgC_3N by He: rate coefficients and astrophysical implications",
  "type": "preprint",
  "updated_at": "2026-11-04T15:20:51Z",
  "url": "https://research.draconitic.com/paper/ca04nbhpxtdz1",
  "venue": "arXiv",
  "versions": []
}