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    "headline": "Gaia Points to a Fifth HR 8799 Companion",
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    "dek": "Stellar wobble points to a close-in companion inside the system’s four imaged outer planets.",
    "summary": "Stellar wobble points to a close-in companion inside the system’s four imaged outer planets.",
    "body_text": "A team combined Gaia absolute astrometry and Hipparcos–Gaia proper-motion anomalies with radial velocities and high-contrast imaging to infer another substellar companion in the HR 8799 system. The allowed orbits span roughly 0.3 to 6 astronomical units, with solutions peaking around 2 to 3 AU and masses near 10 to 14 Jupiters. Dynamical modeling says a low-eccentricity object in that range can coexist with the long-lived resonant chain of the four directly imaged outer planets and may shape the inner edge of the warm debris belt. It is an indirect astrometric inference, not a fifth planet photograph.",
    "why_it_matters": "Stellar wobble points to a close-in companion inside the system’s four imaged outer planets.",
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      "It is an indirect astrometric inference, not a fifth planet photograph."
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        "qualification": "It is an indirect astrometric inference, not a fifth planet photograph."
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    "tags": [
      "Gaia",
      "exoplanets",
      "astrometry"
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      "title": "arXiv preprint 2609.20996",
      "publisher": "arXiv",
      "url": "https://arxiv.org/abs/2609.20996",
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      "published_at": "2026-09-17T14:51:40.000-04:00",
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    "title": "Gaia Points to a Fifth HR 8799 Companion",
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