{"paper":{"title":"The Orbit and Origin of the Ultra-faint Dwarf Galaxy Segue 1","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.GA","authors_text":"A. Wetzel, E. J. Tollerud, M. Lokken, N. Kallivayalil, P. Zivick, S. T. Linden, T. K. Fritz","submitted_at":"2017-11-24T19:00:01Z","abstract_excerpt":"We present the first proper motion measurement for an ultra-faint dwarf spheroidal galaxy, Segue 1, using SDSS and LBC data as the first and second epochs separated by a baseline of $\\sim 10$ years. We obtain a motion of $\\mu_{\\alpha}\\,\\cos(\\delta) = -0.37\\pm0.57$ mas yr$^{-1}$ and $\\mu_{\\delta} =-3.39\\pm0.58$ mas yr$^{-1}$. Combining this with the known line-of-sight velocity, this corresponds to a Galactocentric V$_\\mathrm{rad}=84\\pm9$ and V$_\\mathrm{tan}=164^{+66}_{-55}$ km s$^{-1}$. Applying Milky Way halo masses between 0.8 to 1.6$\\times 10^{12}$ M$_\\odot$ results in an apocenter at 33.9$"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1711.09097","kind":"arxiv","version":3},"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"}