{
  "abstract": "We present Zwicky Transient Facility observations of the interstellar comet 3I/ATLAS to characterize its dust-activity evolution before and after perihelion. Before perihelion, the effective scattering cross section $C_{\\rm e}$ brightened across the inner $2\\times10^4$ km as $C_{\\rm e}\\propto r_{\\rm H}^{-γ}$, with $γ$ increasing from $1.63\\pm0.14$ to $1.88\\pm0.34$ with aperture size. After perihelion, the heliocentric index decreased from $2.44\\pm0.09$ in the $5\\times10^3$ km aperture to $1.54\\pm0.09$ in the $8\\times10^4$ km aperture, indicating faster fading of the inner coma. Under adopted grain-size and residence-time assumptions, the implied dust mass-loss rates are $\\sim123$--$203~{\\rm kg~s^{-1}}$ before perihelion and $\\sim596$--$1412~{\\rm kg~s^{-1}}$ after perihelion. The morphology yields a sunward ejection-speed scale of $v_{\\rm ej}\\sim(190\\pm3)a_{μ{\\rm m}}^{-1/2}~{\\rm m~s^{-1}}$ and an effective perpendicular velocity of $v_\\perp=(79\\pm6)a_{μ{\\rm m}}^{-1/2}~{\\rm m~s^{-1}}$. Post-perihelion surface-brightness profiles transiently steepened to $k\\sim-2.7$ in late November and early December, then became shallower and approached $k=-1.5$ by January. Matched $g-r$ profiles show that this phase coincided with an anomalously blue outer coma that disappeared by January. We characterize the fading component with a projected destruction length of $\\ell_{\\rm DE}\\sim(6.4$--$7.2)\\times10^4$ km. Thermophysical sublimation calculations indicate that this scale, together with the order of magnitude of the water production near the main imaging epoch, is consistent with $a_0\\sim5$--$10~μ{\\rm m}$ icy grains containing a small absorbing carbonaceous fraction of $f_{\\rm C}\\sim0.1\\%$. These results suggest that the early post-perihelion coma likely contained a short-lived, volatile-bearing icy-grain component whose fading contributed to the outer-coma brightness and color evolution",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": "Journal reference: ApJL, 1008, L26 (2026)",
  "arxiv": "2610.21206",
  "author_total": 4,
  "authors": [
    {
      "name": "Bin Liu"
    },
    {
      "name": "Xiaoping Zhang"
    },
    {
      "name": "Xiaodong Liu"
    },
    {
      "name": "Man-To Hui"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/bdgdx8e3sjae2.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.21206",
  "fulltext_url": null,
  "id": "bdgdx8e3sjae2",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.21206",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "astro-ph.EP"
    ],
    [
      "arxiv",
      "astro-ph.GA"
    ]
  ],
  "openalex": null,
  "pdf_url": "https://arxiv.org/pdf/2610.21206",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-15",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/bdgdx8e3sjae2.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:50Z",
      "native_id": "2610.21206",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.21206"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.GA",
      "subfield": "galaxies"
    },
    {
      "field": "astronomy",
      "origin": "arxiv:astro-ph.EP",
      "subfield": "planetary"
    }
  ],
  "title": "Dust Activity Evolution and Constraints on Icy Grains in the Interstellar Comet 3I/ATLAS",
  "title_text": "Dust Activity Evolution and Constraints on Icy Grains in the Interstellar Comet 3I/ATLAS",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:50Z",
  "url": "https://research.draconitic.com/paper/bdgdx8e3sjae2",
  "venue": "arXiv",
  "versions": [
    {
      "doi": "10.3847/2041-8213/ae9a89",
      "pid": null,
      "relation": "published-as",
      "title": null,
      "venue": null
    }
  ]
}