{
  "id": 5812045,
  "title": "FAST finds two mysterious hydrogen clouds with no visible stars",
  "url": "https://urgent.news/2026/09/05/fast-finds-two-mysterious-hydrogen-clouds-with-no-visible-stars",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-05T18:40:02.000Z",
  "source": {
    "name": "Phys.org",
    "slug": "phys-org",
    "url": "https://phys.org/news/2026-09-fast-mysterious-hydrogen-clouds-visible.html"
  },
  "original_language": "en",
  "account": "Astronomers have discovered two clouds of hydrogen near the Whirlpool galaxy that contain almost no stars, according to a new study published in the Astronomy & Astrophysics journal. Using China's FAST radio telescope, researchers found these clouds, each containing around 3 million times the mass of the Sun in hydrogen, but no detectable optical counterparts. The clouds, designated as Cloud N and Cloud S, have properties consistent with reionization-limited dark-matter halos, or RELHICs. These systems are predicted in the Lambda Cold Dark Matter (LCDM) model of the universe, where low-mass dark-matter halos can retain gas but fail to form stars due to heating from ultraviolet radiation or insufficient density and coldness. While tidal debris from galaxy interactions in the M51 system cannot be entirely ruled out, higher-resolution radio observations are needed to confirm whether these clouds are indeed starless dark-matter halos.",
  "summary": "Astronomers have found two clouds of hydrogen near the Whirlpool galaxy that appear to contain almost no stars. The clouds, discovered with China's FAST radio telescope, each contain roughly 3 million times the mass of the sun in hydrogen but have no detectable optical counterpart. Their properties are outlined in a new paper published in the Astronomy & Astrophysics journal on Aug. 4.",
  "key_points": [
    "Astronomers discovered two hydrogen clouds near Whirlpool galaxy using FAST telescope.",
    "Clouds, Cloud N and Cloud S, contain ~3 million solar masses of hydrogen each.",
    "Clouds lack detectable optical counterparts, suggesting starless status."
  ],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}