{
  "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 and 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 ∼16% (7 σ –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%–97.0% of the planets around FGK stars are rocky, whereas up to 61.6% (ranging from 4.1%–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) ≲0.01%, and more than 55.4% (82.7%) gaseous planets have a water mass fraction (WMF) ≲0.1% (≲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": [
    "The Ohio State University",
    "Institute for Particle Physics and Astrophysics"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 3,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Ji 吉 Wang 王",
      "orcid": "0000-0002-4361-8885"
    },
    {
      "affs": [
        1
      ],
      "name": "Caroline Dorn",
      "orcid": "0000-0001-6110-4610"
    },
    {
      "affs": [
        1
      ],
      "name": "Komal Bali",
      "orcid": "0000-0003-4829-7141"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/c97tbv1226jwn.bib",
  "cited_by": 0,
  "doi": "10.3847/1538-4357/aea407",
  "fulltext_url": null,
  "id": "c97tbv1226jwn",
  "issns": [
    "0004-637X",
    "1538-4357"
  ],
  "landing_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea407",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "3103|Stellar, planetary, and galactic studies"
    ]
  ],
  "openalex": "W7220950738",
  "pdf_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea407/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-08",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/c97tbv1226jwn.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:18:11Z",
      "native_id": "10.3847/1538-4357/aea407",
      "source": "crossref",
      "url": "https://iopscience.iop.org/article/10.3847/1538-4357/aea407"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "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": "peer-reviewed",
  "updated_at": "2026-10-30T12:18:11Z",
  "url": "https://research.draconitic.com/paper/c97tbv1226jwn",
  "venue": "The Astrophysical Journal",
  "versions": []
}