{"paper":{"title":"Reevaluating UMa3/U1: star cluster or the smallest known galaxy?","license":"http://creativecommons.org/licenses/by/4.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"Holger Baumgardt, Sarah M. Sweet, Scot Devlin","submitted_at":"2025-04-30T04:23:10Z","abstract_excerpt":"Ursa Major III/UNIONS 1 (UMa3/U1) is the faintest Milky Way satellite discovered to date, exhibiting a half-light radius of 3 $\\pm$ 1 pc and an absolute V-band magnitude of +2.2 $\\pm$ 0.4. Previous studies suggest UMa3/U1 is a dwarf galaxy, based on its large internal velocity dispersion and the improbability (indicated by dynamical cluster simulations) of its long-term survival if it were a dark-matter-free star cluster. In this paper, we model the evolution of UMa3/U1 as a star cluster using collisional N-body simulations that include a description of stellar evolution and the external tidal"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"2504.21301","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/2504.21301/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"}