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  "story": {
    "story_id": "mp-2026-09-08-007",
    "source_story_id": "tmp-story-jwst-exomoon-limits",
    "edition_id": "mp-2026-09-08-morning-0061",
    "edition_url": "https://themachinepress.com/edition/2026-09-08",
    "position": 7,
    "story_type": "dispatch",
    "section": "research",
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    "headline": "Twelve Transits Ruled Out Moons One-Tenth Earth's Radius",
    "slug": "twelve-transits-ruled-out-moons-one-tenth-earth-s-radius",
    "dek": "JWST found no moon around LP 890-9c, but excluded objects comparable in size to several Solar System moons across the planet's Hill region.",
    "summary": "JWST found no moon around LP 890-9c, but excluded objects comparable in size to several Solar System moons across the planet's Hill region.",
    "body_text": "The search combined twelve JWST transits of the rocky temperate-zone exoplanet LP 890-9c. It found no exomoon and reports a 95-percent exclusion of moons at 0.1 Earth radii across the full Hill region, a scale that includes analogs of Europa, Rhea and Umbriel. The authors caution that LP 890-9c orbits at 0.04 astronomical units, where tides already make long-term survival of larger moons unlikely. The main instrument result is sensitivity: pairing a noisy transit with one clean epoch restored limits comparable with other two-epoch combinations.",
    "why_it_matters": "JWST found no moon around LP 890-9c, but excluded objects comparable in size to several Solar System moons across the planet's Hill region.",
    "limitations": [],
    "importance": 8,
    "canonical_url": "https://themachinepress.com/story/mp-2026-09-08-007/twelve-transits-ruled-out-moons-one-tenth-earth-s-radius",
    "json_url": "https://themachinepress.com/story/mp-2026-09-08-007.json",
    "first_published_at": "2026-09-08T09:00:00.000-04:00",
    "modified_at": "2026-09-08T09:00:00.000-04:00",
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    "carryover_reason": null,
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        "text": "JWST found no moon around LP 890-9c, but excluded objects comparable in size to several Solar System moons across the planet's Hill region.",
        "source_ids": [
          "source-2026-09-08-007"
        ],
        "qualification": null
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    "source_ids": [
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    "tags": [
      "JWST",
      "exomoons",
      "LP 890-9c"
    ],
    "image_url": null,
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-09-08-007",
      "title": "arXiv preprint 2609.05301",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.05301",
      "canonical_url": "https://arxiv.org/abs/2609.05301",
      "source_type": "primary_research",
      "is_primary_source": true,
      "published_at": "2026-09-04T11:53:59.000-04:00",
      "accessed_at": "2026-09-08T08:20:00.000-04:00",
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  "corrections": [],
  "publisher": {
    "name": "The Machine Press",
    "url": "https://themachinepress.com",
    "description": "A daily newspaper for the age of artificial intelligence."
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  "cite_this_report": {
    "title": "Twelve Transits Ruled Out Moons One-Tenth Earth's Radius",
    "publisher": "The Machine Press",
    "published_at": "2026-09-08T09:00:00.000-04:00",
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