{
  "abstract": "Water and methanol are the fundamental constituents of interstellar and cometary ices; understanding their abundances in disks is therefore of high importance to reveal how this ice reservoir evolves across the timeline of star and planet formation. We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 5 line emission observations of water and methanol in the warm Herbig disks of HD 100546 and IRS 48. While the IRS 48 disk is methanol-rich, water vapor is not detected, implying a high methanol-to-water column density ratio of >0.2, possibly reflecting a distinct ice composition. Methanol and water are both detected in the HD 100546 disk, leading to a CH ₃ OH/H ₂ O ratio of ∼0.02, consistent with the median of the cometary distribution and with the lower edge of the distribution of young stellar objects (YSOs). We suggest that the gas-phase methanol-to-water ratio in the HD 100546 disk directly reveals the ice reservoir subsequently sublimated in the warm disk stage. Moreover, we report a methyl formate-to-methanol ratio in the IRS 48 disk of ∼0.2, consistent with the upper edge of the distribution of YSOs. The methyl formate-to-methanol ratio in the HD 100546 disk is ∼2, much higher than in younger and older sources, possibly reflecting a chemical enhancement of gas-phase methyl formate. We additionally constrain non-LTE conditions, optical depths, and emitting regions of the methanol lines in both disks. These results offer a new opportunity to probe the chemical trail of molecular complexity in the intermediate-disk stage, bridging early and late phases of the star and planet formation history.",
  "abstract_shown": true,
  "affiliations": [
    "Università degli Studi di Milano",
    "European Southern Observatory",
    "Center for Astrophysics—Harvard & Smithsonian",
    "Max-Planck Institute for Astronomy (MPIA)",
    "Universidad de Chile",
    "Joint ALMA Observatory (JAO)",
    "European Southern Observatory (ESO)",
    "Alma Mater Studiorum Università di Bologna"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 9,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Luna Rampinelli",
      "orcid": "0009-0001-2795-8468"
    },
    {
      "affs": [
        0
      ],
      "name": "Stefano Facchini",
      "orcid": "0000-0003-4689-2684"
    },
    {
      "affs": [
        1
      ],
      "name": "Marta De Simone",
      "orcid": "0000-0001-5659-0140"
    },
    {
      "affs": [
        0
      ],
      "name": "Margot Leemker",
      "orcid": "0000-0003-3674-7512"
    },
    {
      "affs": [
        2
      ],
      "name": "Alice S. Booth",
      "orcid": "0000-0003-2014-2121"
    },
    {
      "affs": [
        3
      ],
      "name": "Myriam Benisty",
      "orcid": "0000-0002-7695-7605"
    },
    {
      "affs": [
        4
      ],
      "name": "Pietro Curone",
      "orcid": "0000-0003-2045-2154"
    },
    {
      "affs": [
        5,
        6
      ],
      "name": "Elizabeth Humphreys",
      "orcid": "0000-0001-9549-6421"
    },
    {
      "affs": [
        7
      ],
      "name": "Leonardo Testi",
      "orcid": "0000-0003-1859-3070"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/b90bhcynn1hb2.bib",
  "cited_by": 0,
  "doi": "10.3847/1538-4357/aeb11e",
  "fulltext_url": null,
  "id": "b90bhcynn1hb2",
  "issns": [
    "1538-4357",
    "0004-637X"
  ],
  "landing_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aeb11e",
  "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": [
    [
      "feed-journal",
      "astronomy/general"
    ]
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  "pdf_url": "https://iopscience.iop.org/article/10.3847/1538-4357/aeb11e/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-06",
  "publisher": "American Astronomical Society",
  "ris": "https://research.draconitic.com/paper/b90bhcynn1hb2.ris",
  "sources": [
    {
      "first_seen": "2026-11-06T06:20:02Z",
      "native_id": "10.3847/1538-4357/aeb11e",
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  "subjects": [
    {
      "field": "astronomy",
      "origin": "journal-openalex:3103|Stellar, planetary, and galactic studies",
      "subfield": "stellar"
    }
  ],
  "title": "An ALMA View on Molecular Complexity: Water, Methanol, and Methyl Formate in the HD 100546 and IRS 48 Disks",
  "title_text": "An ALMA View on Molecular Complexity: Water, Methanol, and Methyl Formate in the HD 100546 and IRS 48 Disks",
  "type": "peer-reviewed",
  "updated_at": "2026-11-08T00:21:13Z",
  "url": "https://research.draconitic.com/paper/b90bhcynn1hb2",
  "venue": "The Astrophysical Journal",
  "versions": []
}