{"paper":{"title":"\"Distance mapping\" and the 3-D structure of BB +30 3639","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":["astro-ph.GA"],"primary_cat":"astro-ph.SR","authors_text":"S. Akras, W. Steffen","submitted_at":"2012-03-15T21:38:17Z","abstract_excerpt":"BD +30 3639 is a member of a group of uncommon planetary nebula with Wolf-Rayet central star and higher expansion velocities in [O III] than in [N II] lines. Images and high-resolution spectra from the literature are used in order to construct a 3-D model of the nebula using the morpho-kinematic code SHAPE. We find that two homologous expansion laws are needed for the [N II] and [O III] shell. We conclude that the internal velocity field of BD +30 3639 decreases with the distance from the central star at least between the [O III] and [N II] shells. A cylindrical velocity component is used to r"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1203.3579","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"}