{
  "abstract": "As physical samples of distant planetary systems, the compositions of interstellar objects (ISOs) should correlate with the properties of their diverse parent stars. We combine a chemical partition model with a sample of stellar elemental abundances from APOGEE DR17 to predict the abundances of commonly-observed cometary volatiles in ISOs. We find that the compositions of ISOs vary significantly between different stars. In particular, we predict a strong correlation between an ISO's ammonia abundance and its parent star's metallicity: high-metallicity stars will create ISOs rich in ammonia. This suggests the production rates of NH$_3$'s photolytic daughter products are an ideal observational tracer for the origins of ISOs. We infer that 2I/Borisov formed around a star of near-solar metallicity ($-0.4\\lesssim[\\mathrm{Fe}/\\mathrm{H}]\\lesssim0.3$), and corroborate the velocity- and isotope-based inferences that 3I/ATLAS formed around a lower-metallicity star ($-0.8\\lesssim[\\mathrm{Fe}/\\mathrm{H}]\\lesssim0.0$). The production rates of 2I and 3I imply both only contain hypervolatiles such as CO and N$_2$ that are trapped in other less-volatile ices, similar to typical Solar System comets. Despite this, we argue that true hypervolatile-ice-rich ISOs may exist; they would exhibit high CO and N$_2$ production rate ratios, possibly similar to those of C/2016 R2 (PanSTARRS). Our predictions provide context for future ISO discoveries, opening a path to link the properties of their origin systems to observable production rates.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.30827",
  "author_total": 5,
  "authors": [
    {
      "name": "Matthew J. Hopkins"
    },
    {
      "name": "Michele T. Bannister"
    },
    {
      "name": "Bertram Bitsch"
    },
    {
      "name": "Chris Lintott"
    },
    {
      "name": "John C. Forbes"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/0qcfsz8vt0kwq.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.30827",
  "fulltext_url": null,
  "id": "0qcfsz8vt0kwq",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.30827",
  "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.EP"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ],
    [
      "openalex",
      "3103|Astro and Planetary Science"
    ]
  ],
  "openalex": "W7214619196",
  "pdf_url": "https://arxiv.org/pdf/2609.30827",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-25",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/0qcfsz8vt0kwq.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:24:52Z",
      "native_id": "2609.30827",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.30827"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "On the Compositions of Interstellar Objects",
  "title_text": "On the Compositions of Interstellar Objects",
  "type": "preprint",
  "updated_at": "2026-10-30T12:24:52Z",
  "url": "https://research.draconitic.com/paper/0qcfsz8vt0kwq",
  "venue": "arXiv",
  "versions": []
}