{
  "abstract": "We present Hubble Space Telescope Advanced Camera for Surveys observations of Gep I, a globular cluster (GC) candidate in the low-mass ($M_{\\star}\\sim 6.5 \\times 10^5\\,M_{\\odot}$) M31 dwarf spheroidal (dSph) satellite Andromeda XXV (And XXV). We confirm the nature of this object and provide the first detailed characterisation of its resolved stellar populations using a colour-magnitude diagram (CMD) that reaches 2 magnitudes below the horizontal branch. We compare Gep I's metallicity and distance with those of the surrounding And XXV stellar population, and find them to be strikingly similar, consistent with a physical association between the GC and the dSph. Gep I is very extended ($R_h=24^{+5}_{-4}$ pc) and faint ($M_V = -4.5 \\pm 0.2$ mag), similar to the star clusters residing in other low-mass dwarf galaxies. It is characterised by a very low metallicity ($\\rm [Fe/H] = -2.4^{+0.3}_{-0.4}\\,$dex) and a red horizontal branch morphology, a combination also seen in suspected accreted GCs in the M31 halo and in the Local Group dwarf irregular galaxy NGC 6822. While Gep I is most likely a genuine star cluster, the current data do not exclude the tantalising possibility that it consists of And XXV stars temporarily captured by a dark subhalo orbiting within the dSph's potential well.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: Mon Not R Astron Soc (2026)",
  "arxiv": "2608.26959",
  "author_total": 9,
  "authors": [
    {
      "name": "Chiara Crociati"
    },
    {
      "name": "Annette M. N. Ferguson"
    },
    {
      "name": "Gracie McGill"
    },
    {
      "name": "Raffaele Pascale"
    },
    {
      "name": "Anna Genina"
    },
    {
      "name": "Pete B. Kuzma"
    },
    {
      "name": "Dougal Mackey"
    },
    {
      "name": "Alan W. McConnachie"
    },
    {
      "name": "Rokas Žemaitis"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/90dkbkg65s5n2.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2608.26959",
  "fulltext_url": null,
  "id": "90dkbkg65s5n2",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2608.26959",
  "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/2608.26959",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-31",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/90dkbkg65s5n2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:21:41Z",
      "native_id": "2608.26959",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2608.26959"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    }
  ],
  "title": "The solitary star cluster of the Andromeda XXV dwarf spheroidal",
  "title_text": "The solitary star cluster of the Andromeda XXV dwarf spheroidal",
  "type": "preprint",
  "updated_at": "2026-10-30T12:21:41Z",
  "url": "https://research.draconitic.com/paper/90dkbkg65s5n2",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.1093/mnras/stag1649",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}