{
  "abstract": "Context . Carbocations are key species in interstellar chemistry, providing entry points for building larger hydrocarbons. CH + , and more recently, CH 3 + , have been detected. Other carbocations await detection to provide a comprehensive view of the astrochemical network that is at work in the interstellar medium. Aims . We search for CH 2 + in objects in which CH 3 + was detected and evaluate the most favorable conditions for detecting the elusive CH 2 + reactive cation. Methods . We calculated the CH 2 + rotational and rovibrational transitions expected to contribute in the mid- to far-infrared, focusing on the lower-energy rovibrational levels. We then calculated CH 2 + infrared emission spectra at different excitation temperatures and compared them to JWST spectra of the externally irradiated disk d203-506 in Orion, where CH + and CH 3 + have already been detected. We used thermochemical models to predict the abundance and spatial morphology of CH 2 + to better understand its nondetection. Results . The comparison to JWST spectra allowed us to provide excitation-temperature-dependent upper limits to the excited column density. These are several times lower than those detected for CH + and CH 3 + in their excited states. Based on model calculations for photodissociation regions and assuming similar excitation temperatures, the upper limit derived from observations and CH 2 + model spectrum is either slightly above or below the column density expected from models of photodissociation regions. We provide a list of tabulated transitions to allow the community to search for this carbocation in future observations as CH 2 + is key in providing observational constraints on astrochemical models.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": null,
  "author_total": 17,
  "authors": [
    {
      "name": "M. Zannese"
    },
    {
      "name": "L H Coudert"
    },
    {
      "name": "E. Dartois"
    },
    {
      "name": "P. Dell’ova"
    },
    {
      "name": "O. Roncero"
    },
    {
      "name": "P. del Mazo-Sevillano"
    },
    {
      "name": "U. Jacovella"
    },
    {
      "name": "B. Gans"
    },
    {
      "name": "J R Goicoechea"
    },
    {
      "name": "D. van de Putte"
    },
    {
      "name": "C. Boersma"
    },
    {
      "name": "E. Habart"
    },
    {
      "name": "E. Peeters"
    },
    {
      "name": "J. Cami"
    },
    {
      "name": "R. Chown"
    },
    {
      "name": "I. Schroetter"
    },
    {
      "name": "O. Kannavou"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/56rqmrgrn1hsb.bib",
  "cited_by": 0,
  "doi": "10.1051/0004-6361/202660602",
  "fulltext_url": null,
  "id": "56rqmrgrn1hsb",
  "issns": [
    "0004-6361",
    "1432-0746"
  ],
  "landing_url": "https://hal.science/hal-05780139v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "0.sdu"
    ],
    [
      "openalex",
      "3103|Astrophysics and Star Formation Studies"
    ]
  ],
  "openalex": "W7166646060",
  "pdf_url": "https://hal.science/hal-05780139/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-11",
  "publisher": "EDP Sciences",
  "ris": "https://research.draconitic.com/paper/56rqmrgrn1hsb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:48Z",
      "native_id": "hal-05780139",
      "source": "hal",
      "url": "https://hal.science/hal-05780139v1"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Astrophysics and Star Formation Studies",
      "subfield": "stellar"
    }
  ],
  "title": "Searching for the elusive CH 2 + with the James Webb Space Telescope",
  "title_text": "Searching for the elusive CH 2 + with the James Webb Space Telescope",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:48Z",
  "url": "https://research.draconitic.com/paper/56rqmrgrn1hsb",
  "venue": "Astronomy & Astrophysics - A&A",
  "versions": []
}