{
  "abstract": "Small exoplanets on close-in orbits are exposed to high levels of stellar irradiation, which can effectively remove low-mass primordial H/He envelopes through atmospheric escape. Under these conditions, planets whose masses and radii are incompatible with both bare rocky interiors and extended H-dominated atmospheres are therefore expected to host high mean molecular weight atmospheres, making them promising candidates for volatile-rich hot water worlds. We present the first detailed characterisation of the low-density super-Earth TOI-2211 b (P~3.09 d), a recently validated transiting planet orbiting a K type star (G mag: 9.1). Combining TESS and CHEOPS photometry with radial velocity measurements from HARPS, ESPRESSO, and KPF, we precisely constrain the planet's radius and mass to $1.457 \\pm 0.047$ R$_\\oplus$ and $2.69 \\pm 0.56$ M$_\\oplus$. We also identify an outer, non-transiting planetary candidate (P~15.6 d, Msin(i) $ = 8.53 \\pm 1.04$ M$_\\oplus$) in the radial velocity data. We investigate the internal structure of the transiting planet and assess the stability of the inferred volatile envelopes through a detailed evaporation analysis, thereby identifying TOI-2211 b as a promising hot water world candidate. TOI-2211 b therefore joins the small but growing sample of these close-in low-density super-Earths, which represent particularly interesting targets for testing current planet formation and evolution theories. Additionally, we investigate the full architecture of the planetary system using a generative model of planet formation and evolution, with the resulting posterior distributions showing a clear over-density consistent with the observed orbital period and minimal mass of the non-transiting planetary candidate identified in the radial velocity data.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.08922",
  "author_total": 101,
  "authors": [
    {
      "name": "J. A. Egger"
    },
    {
      "name": "P. Cortés-Zuleta"
    },
    {
      "name": "D. Kubyshkina"
    },
    {
      "name": "H. P. Osborn"
    },
    {
      "name": "S. Marques"
    },
    {
      "name": "I. Crossfield"
    },
    {
      "name": "A. Deline"
    },
    {
      "name": "S. Ulmer-Moll"
    },
    {
      "name": "A. E. Simon"
    },
    {
      "name": "G. Scandariato"
    },
    {
      "name": "A. C. M. Correia"
    },
    {
      "name": "Y. N. E. Eschen"
    },
    {
      "name": "D. Gandolfi"
    },
    {
      "name": "V. Adibekyan"
    },
    {
      "name": "A. Bonfanti"
    },
    {
      "name": "C. Pezzotti"
    },
    {
      "name": "P. H. Premnath"
    },
    {
      "name": "S. G. Sousa"
    },
    {
      "name": "T. G. Wilson"
    },
    {
      "name": "L. Fossati"
    },
    {
      "name": "R. Eltschinger"
    },
    {
      "name": "Y. Alibert"
    },
    {
      "name": "D. Degen"
    },
    {
      "name": "G. Lacedelli"
    },
    {
      "name": "T. Zingales"
    },
    {
      "name": "B. Akinsanmi"
    },
    {
      "name": "R. Alonso"
    },
    {
      "name": "T. Bárczy"
    },
    {
      "name": "D. Barrado"
    },
    {
      "name": "S. C. C. Barros"
    },
    {
      "name": "W. Baumjohann"
    },
    {
      "name": "W. Benz"
    },
    {
      "name": "N. Billot"
    },
    {
      "name": "L. Borsato"
    },
    {
      "name": "A. Brandeker"
    },
    {
      "name": "C. Broeg"
    },
    {
      "name": "M. Buder"
    },
    {
      "name": "A. Castro-González"
    },
    {
      "name": "A. Collier Cameron"
    },
    {
      "name": "C. Corral Van Damme"
    },
    {
      "name": "Sz. Csizmadia"
    },
    {
      "name": "P. E. Cubillos"
    },
    {
      "name": "M. B. Davies"
    },
    {
      "name": "M. Deleuil"
    },
    {
      "name": "O. D. S. Demangeon"
    },
    {
      "name": "B. -O. Demory"
    },
    {
      "name": "A. Derekas"
    },
    {
      "name": "B. Edwards"
    },
    {
      "name": "D. Ehrenreich"
    },
    {
      "name": "A. Erikson"
    },
    {
      "name": "A. Fortier"
    },
    {
      "name": "M. Fridlund"
    },
    {
      "name": "K. Gazeas"
    },
    {
      "name": "M. Gillon"
    },
    {
      "name": "M. Güdel"
    },
    {
      "name": "M. N. Günther"
    },
    {
      "name": "J. Hasiba"
    },
    {
      "name": "A. Heitzmann"
    },
    {
      "name": "Ch. Helling"
    },
    {
      "name": "K. G. Isaak"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/11jc5hbt76xhh.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.08922",
  "fulltext_url": null,
  "id": "11jc5hbt76xhh",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.08922",
  "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/2610.08922",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-06",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/11jc5hbt76xhh.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:27:37Z",
      "native_id": "2610.08922",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.08922"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "Searching for hot water world candidates with CHEOPS: II. A low-density super-Earth orbiting the K dwarf TOI-2211",
  "title_text": "Searching for hot water world candidates with CHEOPS: II. A low-density super-Earth orbiting the K dwarf TOI-2211",
  "type": "preprint",
  "updated_at": "2026-10-30T12:27:37Z",
  "url": "https://research.draconitic.com/paper/11jc5hbt76xhh",
  "venue": "arXiv",
  "versions": []
}