{"paper":{"title":"Modelling the Warm H2 Infrared Emission of the Helix Nebula Cometary Knots","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"2), (2) IAG-USP, (3) Institute of Origins, 4), (4) Institute of Origins, Albert A. Zijlstra (1), Astronomy, Department of Physics, Isabel Aleman (1, Mikako Matsuura (3, Mullard Space Science Laboratory, Rafael K. Kimura (2) ((1) Jodrell Bank Centre for Astrophysics, Ruth Gruenwald (2), The University of Manchester, Universidade de Sao Paulo, University College London, University College London)","submitted_at":"2011-05-18T00:46:17Z","abstract_excerpt":"Molecular hydrogen emission is commonly observed in planetary nebulae. Images taken in infrared H2 emission lines show that at least part of the molecular emission is produced inside the ionised region. In the best-studied case, the Helix nebula, the H2 emission is produced inside cometary knots (CKs), comet-shaped structures believed to be clumps of dense neutral gas embedded within the ionised gas. Most of the H2 emission of the CKs seems to be produced in a thin layer between the ionised diffuse gas and the neutral material of the knot, in a mini photodissociation region (PDR). However, PDR"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1105.3506","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"}