{"paper":{"title":"The initial evolution of SN 1993J: Piston phase versus standard model","license":"http://creativecommons.org/licenses/by-nc-sa/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.HE","authors_text":"C.-I. Bjornsson","submitted_at":"2025-06-08T13:33:32Z","abstract_excerpt":"The evolution of SN 1993J is unlikely to be self-similar. Spatially resolved VLBI-observations show that the velocity of the outer rim of the radio emission region brakes at a few hundred days. The reason for this break remains largely unknown. It is argued here that it is due to the transition between an initial piston phase to a later phase, which is described by the standard model. The properties of the reverse shock are quite different for a piston phase as compared to the standard self-similar model. This affects the expected X-ray emission; for example, the reverse shock becomes transpar"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2506.07137","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":""},"integrity":{"clean":true,"summary":{"advisory":0,"critical":0,"by_detector":{},"informational":0},"endpoint":"/pith/2506.07137/integrity.json","findings":[],"available":true,"detectors_run":[],"snapshot_sha256":"c28c3603d3b5d939e8dc4c7e95fa8dfce3d595e45f758748cecf8e644a296938"},"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"}