{"paper":{"title":"Chemistry and ro-vibrational excitation of CH$^+$ in the planetary nebula NGC 7027","license":"http://creativecommons.org/licenses/by/4.0/","headline":"Chemical pumping significantly enhances ro-vibrational emissions from CH+ in NGC 7027 beyond standard excitation processes.","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Alexandre Faure, Fran\\c{c}ois Lique, Helmut Wiesemeyer, J\\'er\\^ome Loreau, Josh Forer, Milan Sil, Pierre Hily-Blant, Tom\\'as Gonz\\'alez-Lezana","submitted_at":"2026-04-09T14:02:57Z","abstract_excerpt":"Small carbon hydride cations, such as the methylidyne ion (CH$^+$), play an important role in the chemistry of the interstellar medium (ISM). They participate in gas-phase reaction networks leading to the formation of hydrocarbon species that act as precursors to more complex organic molecules. CH$^+$ is a highly reactive ion that is rapidly destroyed by H, H$_2$, and free electrons, making its excitation challenging to model. Its level populations depend not only on radiative and inelastic processes but also on chemical formation and destruction rates, a mechanism known as chemical pumping. W"},"claims":{"count":4,"items":[{"kind":"strongest_claim","text":"RADEX models show that chemical pumping significantly enhances populations above (υ = 0, J = 1), strongly increasing ro-vibrational emission, especially in the υ=2 → 1 band.","source":"verdict.strongest_claim","status":"machine_extracted","claim_id":"C1","attestation":"unclaimed"},{"kind":"weakest_assumption","text":"The chemical structure, temperature, and density profiles from the CLOUDY model accurately represent the nebula, and the new state-resolved collision data plus implemented chemical rates in RADEX capture the dominant excitation without requiring full 1D spatial modeling.","source":"verdict.weakest_assumption","status":"machine_extracted","claim_id":"C2","attestation":"unclaimed"},{"kind":"one_line_summary","text":"Chemical pumping from formation and destruction processes significantly enhances CH+ ro-vibrational populations and emission lines in NGC 7027 beyond radiative and inelastic collisions alone.","source":"verdict.one_line_summary","status":"machine_extracted","claim_id":"C3","attestation":"unclaimed"},{"kind":"headline","text":"Chemical pumping significantly enhances ro-vibrational emissions from CH+ in NGC 7027 beyond standard excitation processes.","source":"verdict.pith_extraction.headline","status":"machine_extracted","claim_id":"C4","attestation":"unclaimed"}],"snapshot_sha256":"9a0e6d2feb73fbf7d99cde25c528808f340f03c8f83f835725e2f55cd01cccbe"},"source":{"id":"2604.08273","kind":"arxiv","version":2},"verdict":{"id":"29e2a616-f72a-449c-906c-51741e26cd07","model_set":{"reader":"grok-4.3"},"created_at":"2026-05-10T17:48:11.934389Z","strongest_claim":"RADEX models show that chemical pumping significantly enhances populations above (υ = 0, J = 1), strongly increasing ro-vibrational emission, especially in the υ=2 → 1 band.","one_line_summary":"Chemical pumping from formation and destruction processes significantly enhances CH+ ro-vibrational populations and emission lines in NGC 7027 beyond radiative and inelastic collisions alone.","pipeline_version":"pith-pipeline@v0.9.0","weakest_assumption":"The chemical structure, temperature, and density profiles from the CLOUDY model accurately represent the nebula, and the new state-resolved collision data plus implemented chemical rates in RADEX capture the dominant excitation without requiring full 1D spatial modeling.","pith_extraction_headline":"Chemical pumping significantly enhances ro-vibrational emissions from CH+ in NGC 7027 beyond standard excitation processes."},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2604.08273/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"references":{"count":10,"sample":[{"doi":"","year":2015,"title":"A., & Alsolami, Z","work_id":"d167aed1-2f94-4695-897e-847a027351a0","ref_index":1,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2017,"title":"Finally, for the pho- todissociation of CH + (reaction R6), theA V-dependent rate co- efficient was taken from Heays et al. (2017). For the reactions R1, R3, and R4, the rate coefficients were fitted ","work_id":"4270a69a-a42f-427a-a967-22474dc4962a","ref_index":2,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2017,"title":"(2017), based on the more accurate but expensive time- dependent wave-packet (TDWP) method, and a good agreement (within a factor of","work_id":"8d687d27-e151-4d05-826a-e565e457ad56","ref_index":3,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2026,"title":"1 of González-Lezana et al","work_id":"003f5ff9-5d14-442e-938d-a0b4a36f90aa","ref_index":4,"cited_arxiv_id":"","is_internal_anchor":false},{"doi":"","year":2017,"title":"The formation tempera- tureT form was taken as 2/3×(E H2(v,J)−∆H o 0), as observed and recommended by Faure et al","work_id":"6978cc9a-5e60-430d-8c77-55624de93468","ref_index":5,"cited_arxiv_id":"","is_internal_anchor":false}],"resolved_work":10,"snapshot_sha256":"931c7f20e0441113efa7b010e33e11f0b90f195616d50114fe6b5812d2c4462f","internal_anchors":0},"formal_canon":{"evidence_count":2,"snapshot_sha256":"41cde586cf006a02e30e4185688b459269dfedb6089645bca8b74479d3766854"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}