{"paper":{"title":"Emission-line Helium Abundances in Highly Obscured Nebulae","license":"","headline":"","cross_cats":[],"primary_cat":"astro-ph","authors_text":"(2) CITA, 3), (3) U. of Kentucky, David R. Ballantyne (2), Gary J. Ferland (2, Jennifer Karr (2), Mary-Helen Armour (1), P. G. Martin (2) ((1) York Univ., Toronto, USA)","submitted_at":"1999-07-27T18:45:33Z","abstract_excerpt":"This paper outlines a way to determine the ICF using only infrared data. We identify four line pairs, [NeIII] 36$\\micron$/[NeII] 12.8$\\micron$, [NeIII]~15.6$\\micron$ /[NeII] 12.8$\\micron$, [ArIII] 9$\\micron$/[ArII] 6.9$\\micron$, and [ArIII] 21$\\micron$/[ArII] 6.9$\\micron$, that are sensitive to the He ICF. This happens because the ions cover a wide range of ionization, the line pairs are not sensitive to electron temperature, they have similar critical densities, and are formed within the He$^+$/H$^+$ region of the nebula. We compute a very wide range of photoionization models appropriate for "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"astro-ph/9907387","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"}