{
  "id": "2505.06228",
  "version": "v1",
  "published": "2025-05-09T17:59:50.000Z",
  "updated": "2025-05-09T17:59:50.000Z",
  "title": "A Machine-Learning Compositional Study of Exoplanetary Material Accreted Onto Five Helium-Atmosphere White Dwarfs with $\\texttt{cecilia}$",
  "authors": [
    "Mariona Badenas-Agusti",
    "Siyi Xu",
    "Andrew Vanderburg",
    "Kishalay De",
    "Patrick Dufour",
    "Laura K. Rogers",
    "Susana Hoyos",
    "Simon Blouin",
    "Javier Viaña",
    "Amy Bonsor",
    "Ben Zuckerman"
  ],
  "comment": "28 pages, 14 figures, 5 tables. Accepted for publication in MNRAS",
  "categories": [
    "astro-ph.EP",
    "astro-ph.IM",
    "astro-ph.SR",
    "cs.LG"
  ],
  "abstract": "We present the first application of the Machine Learning (ML) pipeline $\\texttt{cecilia}$ to determine the physical parameters and photospheric composition of five metal-polluted He-atmosphere white dwarfs without well-characterised elemental abundances. To achieve this, we perform a joint and iterative Bayesian fit to their $\\textit{SDSS}$ (R=2,000) and $\\textit{Keck/ESI}$ (R=4,500) optical spectra, covering the wavelength range from about 3,800\\r{A} to 9,000\\r{A}. Our analysis measures the abundances of at least two $-$and up to six$-$ chemical elements in their atmospheres with a predictive accuracy similar to that of conventional WD analysis techniques ($\\approx$0.20 dex). The white dwarfs with the largest number of detected heavy elements are SDSS J0859$+$5732 and SDSS J2311$-$0041, which simultaneously exhibit O, Mg, Si, Ca, and Fe in their $\\textit{Keck/ESI}$ spectra. For all systems, we find that the bulk composition of their pollutants is largely consistent with those of primitive CI chondrites to within 1-2$\\sigma$. We also find evidence of statistically significant ($>2\\sigma$) oxygen excesses for SDSS J0859$+$5732 and SDSS J2311$-$0041, which could point to the accretion of oxygen-rich exoplanetary material. In the future, as wide-field astronomical surveys deliver millions of public WD spectra to the scientific community, $\\texttt{cecilia}$ aspires to unlock population-wide studies of polluted WDs, therefore helping to improve our statistical knowledge of extrasolar compositions.",
  "revisions": [
    {
      "version": "v1",
      "updated": "2025-05-09T17:59:50.000Z"
    }
  ],
  "analyses": {
    "keywords": [
      "helium-atmosphere white dwarfs",
      "machine-learning compositional study",
      "exoplanetary material",
      "wide-field astronomical surveys deliver millions",
      "sdss j2311"
    ],
    "note": {
      "typesetting": "TeX",
      "pages": 28,
      "language": "en",
      "license": "arXiv",
      "status": "editable"
    }
  }
}