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    "story_id": "mp-2026-10-31-026",
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    "headline": "Nine Eclipses Expand the Ultracompact Census",
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    "dek": "The Zwicky Transient Facility search raised the published sample of eclipsing accreting ultracompact white-dwarf binaries from 21 to 30.",
    "summary": "The Zwicky Transient Facility search raised the published sample of eclipsing accreting ultracompact white-dwarf binaries from 21 to 30.",
    "body_text": "Eclipsing ultracompact binaries are unusually valuable because their masses and radii can be measured with limited dependence on formation models. A Zwicky Transient Facility light-curve search followed by Keck spectroscopy found nine new systems and reanalyzed four earlier reports, with orbital periods from 26 to 65 minutes. The nine discoveries increase the published eclipsing sample from 21 to 30; one hydrogen-only system may be the shortest-period member of its kind. Detailed model-independent mass and radius measurements remain future work.",
    "why_it_matters": "The Zwicky Transient Facility search raised the published sample of eclipsing accreting ultracompact white-dwarf binaries from 21 to 30.",
    "limitations": [
      "The nine discoveries increase the published eclipsing sample from 21 to 30; one hydrogen-only system may be the shortest-period member of its kind.",
      "Detailed model-independent mass and radius measurements remain future work."
    ],
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    "first_published_at": "2026-10-31T09:00:00.000-04:00",
    "modified_at": "2026-10-31T09:00:00.000-04:00",
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        "text": "The Zwicky Transient Facility search raised the published sample of eclipsing accreting ultracompact white-dwarf binaries from 21 to 30.",
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        "qualification": "The nine discoveries increase the published eclipsing sample from 21 to 30; one hydrogen-only system may be the shortest-period member of its kind."
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    "source_ids": [
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    "tags": [
      "white dwarfs",
      "ZTF",
      "eclipsing binaries",
      "astronomy"
    ],
    "image_url": null,
    "corrections": []
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  "sources": [
    {
      "source_id": "source-2026-10-31-015",
      "title": "arXiv preprint 2610.40015, original v1",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2610.40015v1",
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      "source_type": "primary_research",
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      "published_at": "2026-10-28T20:00:00.000-04:00",
      "accessed_at": "2026-10-31T08:25:01.279-04:00",
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  "cite_this_report": {
    "title": "Nine Eclipses Expand the Ultracompact Census",
    "publisher": "The Machine Press",
    "published_at": "2026-10-31T09:00:00.000-04:00",
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