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    "story_id": "mp-2026-09-05-005",
    "source_story_id": "tmp-story-jwst-toi431b-atmosphere",
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    "headline": "A Lava World Dimmed Like It Still Had Air",
    "slug": "a-lava-world-dimmed-like-it-still-had-air",
    "dek": "One JWST partial eclipse placed TOI-431b below the brightness expected from a bare, dark rock, though only at 1.8 sigma.",
    "summary": "One JWST partial eclipse placed TOI-431b below the brightness expected from a bare, dark rock, though only at 1.8 sigma.",
    "body_text": "MIRI measured an 81 ± 16 parts-per-million eclipse from TOI-431b, corresponding to a dayside brightness temperature near 1,967 kelvin. The brightness ratio sits 1.8 sigma below a zero-albedo, zero-redistribution bare-rock model. Because exposed magma is expected to be dark, the team says an atmosphere best explains the lower observed emission through reflection or heat transport. The evidence comes from one partial eclipse and remains tentative; composition and stronger constraints require future observations and improved lava-planet models.",
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    "first_published_at": "2026-09-05T09:00:00.000-04:00",
    "modified_at": "2026-09-05T09:00:00.000-04:00",
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    "tags": [
      "JWST",
      "exoplanets",
      "lava worlds"
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    "image_url": null,
    "corrections": []
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  "sources": [
    {
      "source_id": "source-2026-09-05-005",
      "title": "arXiv preprint 2609.03029",
      "publisher": "arXiv",
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      "published_at": "2026-09-02T14:03:41.000-04:00",
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    "name": "The Machine Press",
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    "title": "A Lava World Dimmed Like It Still Had Air",
    "publisher": "The Machine Press",
    "published_at": "2026-09-05T09:00:00.000-04:00",
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