{
  "abstract": "Whether the high-$α$ disk experienced a continuous or episodic star-formation history remains an open question. Here we investigate the age--metallicity distribution of the high-$α$ disk using approximately 145,000 Gaia DR3 subgiants with $[\\mathrm{Fe/H}]>-1$, 6.5~kpc $\\lesssim R\\lesssim9.5$~kpc, and $|Z|\\lesssim1.5$~kpc. We adopt a forward-modelling framework that accounts for individual age and metallicity uncertainties and corrects for sample selection effects. The reconstructed distribution reveals two components: a broad, dominant population peaking at $\\sim10.6$ Gyr and $[\\mathrm{Fe/H}]\\simeq-0.38$, and an older, more metal-poor population peaking at $\\sim12.4$ Gyr and $[\\mathrm{Fe/H}]\\simeq-0.79$. These features suggest an episodic history of star formation and chemical enrichment in the high-$α$ disk, qualitatively consistent with cosmological simulations in which recurrent gas accretion drives variations in the star formation rate. The age of the older component is close to the $\\sim12.3$~Gyr epoch inferred for the proposed Low-energy--Kraken--Heracles accretion event, suggesting a possible connection between this early interaction and enhanced disk star formation. There is tentative evidence that the dominant population is possibly composed of two sub-components with age distributions peaking at $\\sim11.1$ Gyr and $\\sim10.0$ Gyr, respectively. Together, these results favour a picture in which the high-$α$ disk was built through recurrent episodes of enhanced star formation rather than a single temporally smooth phase, even for the regime of ${\\rm [Fe/H]}>-1$.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.30659",
  "author_total": 5,
  "authors": [
    {
      "name": "Tiancheng Sun"
    },
    {
      "name": "Maosheng Xiang"
    },
    {
      "name": "Jifeng Liu"
    },
    {
      "name": "Meng Zhang"
    },
    {
      "name": "Yaqian Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/7c1h7bb1n18w5.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.30659",
  "fulltext_url": null,
  "id": "7c1h7bb1n18w5",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.30659",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "arxiv",
      "astro-ph.SR"
    ],
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7223341120",
  "pdf_url": "https://arxiv.org/pdf/2610.30659",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-22",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/7c1h7bb1n18w5.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:34:34Z",
      "native_id": "2610.30659",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.30659"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.SR",
      "subfield": "stellar"
    }
  ],
  "title": "The Milky Way's Early Disk Was Built in Bursts. II. The Multi-component Age-Metallicity Structure of the High-$α$ Disk",
  "title_text": "The Milky Way's Early Disk Was Built in Bursts. II. The Multi-component Age-Metallicity Structure of the High-α Disk",
  "type": "preprint",
  "updated_at": "2026-10-30T12:34:34Z",
  "url": "https://research.draconitic.com/paper/7c1h7bb1n18w5",
  "venue": "arXiv",
  "versions": []
}