{
  "abstract": "The formation pathway of the $α$-poor Milky Way thin disc remains under debate. The latest observational data indicates the presence of comparable numbers of old stars in both the low- and high-$α$ disc components, suggesting either coeval or overlapping formation epochs. Using GALAH DR4, we provide evidence that the $α$-poor stars coexist with $α$-rich stars up to $\\sim$12.5 Gyr. Stellar ages of 0.5 Gyr precision were re-derived for nearly $30\\,000$ subgiant stars using accurate effective temperatures ($T_{\\rm{eff}}$) from the infrared flux method (IRFM) together with distances based on Gaia parallaxes. About 22\\% of the sample constitutes a population peaking at 9.2 Gyr, with evidence for an extended old-age tail reaching 12.5 Gyr. Among stars older than 10 and 11 Gyr, between 20 and 30\\% have relative low [$α$/Fe] and solar-like metallicities ($-0.5 \\leq \\mathrm{[Fe/H]} \\leq +0.5$ dex). These stars exhibit kinematics consistent with those of near solar-age $α$-poor stars in the thin disc. These stars can be evolved Sun-like stars, i.e. old solar analogues, whose $T_{\\rm{eff}}$ and gravity modified with the time. Comparison with a well-tested Galactic disc chemical evolution model supports the presence of a significant fraction of old, $α$-poor disc stars, confirming the plausibility of our selection criteria. We provide a catalogue with the selected sample to facilitate spectroscopic follow-ups at high resolution.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.25235",
  "author_total": 4,
  "authors": [
    {
      "name": "Riano E. Giribaldi"
    },
    {
      "name": "Laura Magrini"
    },
    {
      "name": "Marco Palla"
    },
    {
      "name": "Carlos Viscasillas Vázquez"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5fa1gffmadzdq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.25235",
  "fulltext_url": null,
  "id": "5fa1gffmadzdq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.25235",
  "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"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.25235",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-21",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/5fa1gffmadzdq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:23:39Z",
      "native_id": "2609.25235",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.25235"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "The oldest low-$α$ thin disc stars",
  "title_text": "The oldest low-α thin disc stars",
  "type": "preprint",
  "updated_at": "2026-10-30T12:23:39Z",
  "url": "https://research.draconitic.com/paper/5fa1gffmadzdq",
  "venue": "arXiv",
  "versions": []
}