{
  "abstract": "We present multiepoch optical spectroscopy of the interstellar comet 3I/ATLAS obtained between 2025 December and 2026 January (heliocentric distances of 1.8–3.3 au), yielding postperihelion production rates and mixing ratios for CN, C 3 , C 2 , CH, and gaseous metals (Fe i and Ni i ). Our results show that the coma is less depleted in C 2 after perihelion than before, indicative of subsurface activation or compositional heterogeneity. The outgassing profiles reveal a pronounced perihelion asymmetry: the CN and metal production rates decline more gradually outbound than inbound, consistent with the reported behavior of H 2 O and implying a change in the comet’s activity pattern across perihelion. Despite being metal rich relative to its H 2 O content, 3I/ATLAS follows the metal–CO correlation observed in comets of diverse origins, suggesting that gaseous metal release is more closely linked to a CO-bearing volatile reservoir than to H 2 O, potentially in the form of metal carbonyls. In addition, the [O i ] λ 6300 emission shows a significant residual after subtracting the expected contributions from H 2 O, CO 2 , and CO, which may reflect systematic uncertainties in the photodissociation yields of those molecules or a contribution from additional oxygen-bearing parents.",
  "abstract_shown": true,
  "affiliations": [
    "Chinese Academy of Sciences",
    "University of Chinese Academy of Sciences",
    "Planetary Science Institute",
    "Universidad Diego Portales",
    "Beijing Normal University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 7,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Ruining Zhao",
      "orcid": "0000-0003-4936-4959"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Xiliang Zhang",
      "orcid": "0000-0002-9918-9469"
    },
    {
      "affs": [
        2,
        3
      ],
      "name": "Bin Yang"
    },
    {
      "affs": [
        0,
        1
      ],
      "name": "Xiangyu Fan",
      "orcid": "0009-0005-6956-7413"
    },
    {
      "affs": [
        0
      ],
      "name": "Shu Min Wang",
      "orcid": "0000-0003-4489-9794"
    },
    {
      "affs": [
        1
      ],
      "name": "Yang Huang"
    },
    {
      "affs": [
        4,
        0,
        1
      ],
      "name": "Jifeng Liu",
      "orcid": "0000-0002-2874-2706"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/8jybqc9nehskq.bib",
  "cited_by": 11,
  "doi": "10.3847/2041-8213/ae73fe",
  "fulltext_url": null,
  "id": "8jybqc9nehskq",
  "issns": [
    "2041-8205",
    "2041-8213"
  ],
  "landing_url": "https://doi.org/10.3847/2041-8213/ae73fe",
  "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": "W7164309388",
  "pdf_url": "https://iopscience.iop.org/article/10.3847/2041-8213/ae73fe/pdf",
  "pmcid": null,
  "pmid": null,
  "published": "2026-06-12",
  "publisher": "IOP Publishing",
  "ris": "https://research.draconitic.com/paper/8jybqc9nehskq.ris",
  "sources": [
    {
      "first_seen": "2026-11-07T13:21:01Z",
      "native_id": "W7164309388",
      "source": "openalex",
      "url": "https://doi.org/10.3847/2041-8213/ae73fe"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "openalex:1912|Astro and Planetary Science",
      "subfield": "planetary"
    }
  ],
  "title": "Postperihelion Coma Composition of the Interstellar Comet 3I/ATLAS from Optical Spectroscopy",
  "title_text": "Postperihelion Coma Composition of the Interstellar Comet 3I/ATLAS from Optical Spectroscopy",
  "type": "peer-reviewed",
  "updated_at": "2026-11-09T13:21:19Z",
  "url": "https://research.draconitic.com/paper/8jybqc9nehskq",
  "venue": "The Astrophysical Journal Letters",
  "versions": []
}