{
  "abstract": "Ultra-faint dwarf galaxies (UFDs; stellar masses M * < 10 5 M ⊙ ) 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 Ca II K absorption feature, measured from low-resolution ( R ∼ 1000 ) Keck/LRIS spectroscopy of 40 stars in the UFD Segue~1 ( M * ≈ 500 M ⊙ ), 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 ± 0.10 dex and a dispersion of σ = 0.59 ± 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 ($$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": [
    "University of Chicago"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Daisy Bissonette",
      "orcid": "0009-0006-5977-618X"
    },
    {
      "name": "Alexander P. Ji",
      "orcid": "0000-0002-4863-8842"
    },
    {
      "name": "Joshua D. Simon"
    },
    {
      "name": "Joss Bland-Hawthorn",
      "orcid": "0000-0001-7516-4016"
    },
    {
      "name": "Anirudh Chiti",
      "orcid": "0000-0002-7155-679X"
    },
    {
      "name": "Marla Geha"
    },
    {
      "name": "Ting S. Li",
      "orcid": "0000-0002-9110-6163"
    },
    {
      "name": "Anna Frebel"
    },
    {
      "name": "Alice M. Luna",
      "orcid": "0009-0009-9570-0715"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5vn6b11vna4wk.bib",
  "cited_by": 0,
  "doi": "10.33232/001c.172763",
  "fulltext_url": null,
  "id": "5vn6b11vna4wk",
  "issns": [
    "2565-6120"
  ],
  "landing_url": "https://astro.theoj.org/article/172763-the-metallicity-distribution-of-the-ultra-faint-dwarf-galaxy-segue-1",
  "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": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7161124890",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-20",
  "publisher": "Maynooth University",
  "ris": "https://research.draconitic.com/paper/5vn6b11vna4wk.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:19Z",
      "native_id": "10.33232/001c.172763",
      "source": "crossref",
      "url": "https://astro.theoj.org/article/172763-the-metallicity-distribution-of-the-ultra-faint-dwarf-galaxy-segue-1"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "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": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:19Z",
  "url": "https://research.draconitic.com/paper/5vn6b11vna4wk",
  "venue": "The Open Journal of Astrophysics",
  "versions": [
    {
      "doi": "10.48550/arxiv.2605.12810",
      "pid": "5bs2v8pbh98hj",
      "relation": "preprint",
      "title": "The Metallicity Distribution of the Ultra-Faint Dwarf Galaxy Segue 1",
      "venue": "arXiv"
    }
  ]
}