{
  "abstract": "Ultra-faint dwarf galaxies (UFDs; stellar masses $M_* < 10^5\\,M_\\odot$) offer unique insights into early chemical evolution in low-mass systems. However, interpreting their metallicity distribution functions (MDFs) has been challenging due to limited spectroscopic samples, especially beyond the red giant branch. We present metallicities from the CaII K absorption feature, measured from low-resolution ($R\\sim1000$) Keck/LRIS spectroscopy of 40 stars in the UFD Segue 1 ($M_* \\approx 500\\,M_\\odot$), including both red giant branch and main-sequence turnoff stars, resulting in a metallicity sample more than six times larger than previously published data for Segue 1. The resulting MDF has an average [Fe/H] $= -2.52 \\pm 0.10$ dex and a dispersion of $σ= 0.59 \\pm 0.06$ dex, and is best described by a single Gaussian, with no evidence for multimodal substructure. This is consistent with a continuous, short-duration ($\\lesssim$1~Gyr) episode of star formation and chemical enrichment prior to reionization. The nonzero metallicity spread reaffirms its classification as a galaxy. Segue 1 highlights the rich chemical enrichment histories present even in the least massive galaxies, and underscores the importance of deep spectroscopic follow-up to fully characterize these ancient stellar systems.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2605.12810",
  "author_total": 9,
  "authors": [
    {
      "name": "Daisy Bissonette"
    },
    {
      "name": "Alexander P. Ji"
    },
    {
      "name": "Joshua D. Simon"
    },
    {
      "name": "Joss Bland-Hawthorn"
    },
    {
      "name": "Anirudh Chiti"
    },
    {
      "name": "Marla Geha"
    },
    {
      "name": "Ting S. Li"
    },
    {
      "name": "Anna Frebel"
    },
    {
      "name": "Alice M. Luna"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5bs2v8pbh98hj.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2605.12810",
  "fulltext_url": null,
  "id": "5bs2v8pbh98hj",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2605.12810",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2605.12810",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-19",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5bs2v8pbh98hj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:04Z",
      "native_id": "2605.12810",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2605.12810"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "The Metallicity Distribution of the Ultra-Faint Dwarf Galaxy Segue 1",
  "title_text": "The Metallicity Distribution of the Ultra-Faint Dwarf Galaxy Segue 1",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:04Z",
  "url": "https://research.draconitic.com/paper/5bs2v8pbh98hj",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.33232/001c.172763",
      "pid": "5vn6b11vna4wk",
      "relation": "published-as",
      "title": "The Metallicity Distribution of the Ultra-Faint Dwarf Galaxy Segue 1",
      "venue": "The Open Journal of Astrophysics"
    }
  ]
}