{
  "abstract": "The environs of other stellar systems may be directly probed by analyzing the cometary activity of interstellar objects. The recently discovered interstellar object 3I/ATLAS was the subject of an intensive worldwide follow-up campaign in its preperihelion approach. Now, 3I/ATLAS has begun its postperihelion departure from the solar system. In this paper, we report the first postperihelion blue-sensitive integral-field unit spectroscopy of 3I/ATLAS using the Keck Cosmic Web Imager on 2025 November 16. We confirm previously reported CN, Fe, and Ni outgassing along with detections of carbon chain molecules C 2 and C 3 . We calculate production rates for each species. We find Fe and Ni production rates of Q Fe = (9.55 ± 3.96) × 10 25 atoms s −1 and Q Ni = (6.61 ± 2.74) × 10 25 atoms s −1 , resulting in a ratio of log ( Q Ni / Q Fe ) = − 0.16 ± 0.03 , which matches solar system comets well and continues the preperihelion trend of declining log ( Q Ni / Q Fe ) with r h . We investigate the radial distributions of these elemental species and find characteristic e -folding radii of 3880 ± 39 km for Ni, 6053 ± 68 km for CN, 4194 ± 45 km for C 2 , and 3833 ± 45 km for C 3 . Compared to preperihelion measurements, these radii have increased by a factor of ∼6.5–7. Our postperihelion observations reveal that 3I/ATLAS continues to exhibit cometary behavior broadly consistent with solar system comets.",
  "abstract_shown": true,
  "affiliations": [
    "University of Hawai'i",
    "Planetary Science Institute",
    "Universidad Diego Portales",
    "Georgia Institute of Technology",
    "NSF-Simons AI Institute for the Sky (SkAI)",
    "University of Illinois Urbana-Champaign",
    "Chinese Academy of Sciences"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 13,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "W. B. Hoogendam",
      "orcid": "0000-0003-3953-9532"
    },
    {
      "affs": [
        0
      ],
      "name": "D. O. Jones",
      "orcid": "0000-0002-6230-0151"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Bin Yang",
      "orcid": "0000-0002-5033-9593"
    },
    {
      "affs": [
        0
      ],
      "name": "Benjamin J. Shappee",
      "orcid": "0000-0003-4631-1149"
    },
    {
      "affs": [
        3,
        0
      ],
      "name": "James J. Wray",
      "orcid": "0000-0001-5559-2179"
    },
    {
      "affs": [
        0
      ],
      "name": "Karen J. Meech",
      "orcid": "0000-0002-2058-5670"
    },
    {
      "affs": [
        0
      ],
      "name": "Chris Ashall",
      "orcid": "0000-0002-5221-7557"
    },
    {
      "affs": [
        0
      ],
      "name": "D. Desai",
      "orcid": "0000-0002-2164-859X"
    },
    {
      "affs": [
        4,
        0,
        5
      ],
      "name": "Jason T. Hinkle",
      "orcid": "0000-0001-9668-2920"
    },
    {
      "affs": [
        0
      ],
      "name": "Andrew Hoffman",
      "orcid": "0000-0002-8732-6980"
    },
    {
      "affs": [
        0
      ],
      "name": "K. Medler",
      "orcid": "0000-0001-7186-105X"
    },
    {
      "affs": [
        0
      ],
      "name": "Cameron Pfeffer",
      "orcid": "0000-0001-9117-6260"
    },
    {
      "affs": [
        6
      ],
      "name": "Ruining Zhao",
      "orcid": "0000-0003-4936-4959"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/5kn8xaxkt6jab.bib",
  "cited_by": 14,
  "doi": "10.3847/1538-4357/ae6243",
  "fulltext_url": null,
  "id": "5kn8xaxkt6jab",
  "issns": [
    "0004-637X",
    "1538-4357"
  ],
  "landing_url": "https://doi.org/10.3847/1538-4357/ae6243",
  "language": "en",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "1912|Astro and Planetary Science"
    ]
  ],
  "openalex": "W7162636673",
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-05-28",
  "publisher": "IOP Publishing",
  "ris": "https://research.draconitic.com/paper/5kn8xaxkt6jab.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T13:21:01Z",
      "native_id": "W7162636673",
      "source": "openalex",
      "url": "https://doi.org/10.3847/1538-4357/ae6243"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:1912|Astro and Planetary Science",
      "subfield": "planetary"
    }
  ],
  "title": "Postperihelion Integral Field Spectroscopy of the Interstellar Comet 3I/ATLAS",
  "title_text": "Postperihelion Integral Field Spectroscopy of the Interstellar Comet 3I/ATLAS",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T13:21:19Z",
  "url": "https://research.draconitic.com/paper/5kn8xaxkt6jab",
  "venue": "The Astrophysical Journal",
  "versions": []
}