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    "story_id": "mp-2026-09-12-027",
    "source_story_id": "tmp-story-wasp12b-obliquity-tides-front-rail",
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    "headline": "A Hidden Planet Could Not Explain WASP-12b’s Fall",
    "slug": "a-hidden-planet-could-not-explain-wasp-12b-s-fall",
    "dek": "The companion needed to sustain the hot Jupiter’s obliquity would be too massive to hide in existing radial-velocity data.",
    "summary": "The companion needed to sustain the hot Jupiter’s obliquity would be too massive to hide in existing radial-velocity data.",
    "body_text": "WASP-12b’s orbit is shrinking faster than standard stellar-tide models explain. One proposal gives the planet persistent obliquity tides, maintained by a nearby companion. Reworking the angular-momentum transfer, the authors find that companion would need at least about 65 Earth masses, not the earlier estimate near 10. Existing radial-velocity observations exclude such an object; within three astronomical units, the reported 95% limit is roughly 14 meters per second. The mechanism therefore cannot account for the decay, whose cause remains open.",
    "why_it_matters": "The companion needed to sustain the hot Jupiter’s obliquity would be too massive to hide in existing radial-velocity data.",
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      "Reworking the angular-momentum transfer, the authors find that companion would need at least about 65 Earth masses, not the earlier estimate near 10.",
      "The mechanism therefore cannot account for the decay, whose cause remains open."
    ],
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    "first_published_at": "2026-09-12T09:00:00.000-04:00",
    "modified_at": "2026-09-12T09:00:00.000-04:00",
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        "text": "The companion needed to sustain the hot Jupiter’s obliquity would be too massive to hide in existing radial-velocity data.",
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        "qualification": "Reworking the angular-momentum transfer, the authors find that companion would need at least about 65 Earth masses, not the earlier estimate near 10."
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    "source_ids": [
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    "tags": [
      "exoplanets",
      "orbital decay",
      "WASP-12b"
    ],
    "image_url": null,
    "corrections": []
  },
  "sources": [
    {
      "source_id": "source-2026-09-12-016",
      "title": "arXiv preprint 2609.11925",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.11925",
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      "source_type": "primary_research",
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      "published_at": null,
      "accessed_at": "2026-09-12T08:27:00.000-04:00",
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    "name": "The Machine Press",
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  "cite_this_report": {
    "title": "A Hidden Planet Could Not Explain WASP-12b’s Fall",
    "publisher": "The Machine Press",
    "published_at": "2026-09-12T09:00:00.000-04:00",
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