{"paper":{"title":"SDSO1 is a Shocked Ghost Planetary Nebula in Front of M 31","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Alberto Noriega-Crespo, Biny Sebastian, Carl Bjork, Lewis McCallum, Marcel Dreschsler, Mark Petersen, Patrick Ogle, Patrick Sparkman, R. Michael Rich, Sendhil Chinnasamy, Steeve Body, Tarun Kottary, Tim Schaeffer, Xavier Strottner, Yann Sainty","submitted_at":"2025-07-21T17:44:19Z","abstract_excerpt":"We present new, deep narrowband imagery and discuss the nature of SDSO 1, the large [O III]-emitting nebula centered 1.5 degrees SE of M 31. We find strong evidence to support the hypothesis that SDSO 1 is unrelated to M 31 and is instead a faded, giant (D = 20 pc), ghost planetary nebula (GPN) expelled by the symbiotic WD binary star EG Andromedae. The associated 45-pc long turbulent tail, seen in projection in front of M 31, yields an estimated age of 400 kyr. The initial hypersonic velocity of 91 km/s drives a strong bow shock into the local interstellar medium and a reverse shock into the "},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2507.15834","kind":"arxiv","version":2},"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/2507.15834/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"}