{
  "abstract": "We investigate the rocky and volatile composition of small exoplanets by modeling the population-level distribution of densities using a mixture framework that links interior structure models to observable quantities. We analyze three complementary samples spanning different stellar environments: the Luque \\& Pallé M-dwarf sample, the DACE M-dwarf sample, and the DACE FGK sample. We consider a log-normal parameterization, which captures a characteristic core mass fraction (CMF) and the intrinsic dispersion to describe a single rocky population. The single rocky population inference suggests a higher CMF for small planets around FGK stars than those around M stars by $\\sim$16\\% (7-11 $σ$ depending on sample selection). We also consider a power-law parameterization, which probes clustering near compositional boundaries at CMF=0.32. The power-law parameterization provides an alternative interpretation: 89.9\\% to 97.0\\% of the planets around FGK stars are rocky whereas up to 61.6\\% (ranging from 4.1\\% to 61.6\\%) of planets around M stars are rocky. In addition, we find that volatile mass fractions are highly concentrated. For example, to describe the DACE M-dwarf sample using a mixture of rocky, water-rich, and gas-rich planets, we find that more than 99.5\\% gaseous planets have an atmospheric mass fraction (AMF) $\\lesssim 0.01\\%$, and more than 55.4\\% (82.7\\%) gaseous planets have a water mass fraction (WMF) $\\lesssim 0.1\\%$ ($\\lesssim 1\\%$). These results suggest that while volatile-bearing planets are common, their composition and prevalence depend strongly on stellar environment, and their volatile inventories are tightly constrained by formation and evolutionary processes.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.09319",
  "author_total": 3,
  "authors": [
    {
      "name": "Ji Wang"
    },
    {
      "name": "Caroline Dorn"
    },
    {
      "name": "Komal Bali"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/26rb43zn11x23.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.09319",
  "fulltext_url": null,
  "id": "26rb43zn11x23",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.09319",
  "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"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2609.09319",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-08",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/26rb43zn11x23.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:20:12Z",
      "native_id": "2609.09319",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.09319"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "A Stellar-Type Dependence in the Rocky and Volatile Composition of Small Exoplanets",
  "title_text": "A Stellar-Type Dependence in the Rocky and Volatile Composition of Small Exoplanets",
  "type": "preprint",
  "updated_at": "2026-10-30T12:20:12Z",
  "url": "https://research.draconitic.com/paper/26rb43zn11x23",
  "venue": "arXiv",
  "versions": []
}