Swinburne astronomers find AGC 322753, a dark galaxy candidate with 2 billion solar masses of hydrogen
A gas cloud 310 million light-years away holds about two billion solar masses of hydrogen but no detected starlight; its nature as a dark galaxy is not yet confirmed.
Astronomers at Swinburne University of Technology have reported AGC 322753, a candidate for a dark galaxy: a large hydrogen reservoir in which few or no stars have formed. The object lies about 310 million light-years away and cannot be seen in visible-light images. The authors put its hydrogen mass at roughly two billion solar masses, according to futurezone.de, which cites Phys.org and a paper in Monthly Notices of the Royal Astronomical Society futurezone.de
futurezone.defuturezone.deOpen source ↗. The paper is titled "AGC 322753: A dark galaxy candidate detected by ALFALFA and FASHI" (2026).
Radio data show a rotating gas disk
For the study, the researchers analysed data from the FAST and Arecibo radio telescopes. Both instruments can detect neutral hydrogen even if a galaxy emits no visible light futurezone.de
futurezone.defuturezone.deOpen source ↗. The measurements show a signal with two distinct peaks, which indicates a rotating gas disk. According to the authors, this is evidence for an ordered stellar system
futurezone.de
futurezone.defuturezone.deOpen source ↗.
Hydrogen is normally an important raw material for forming new stars. That makes it all the more unusual that no corresponding starlight has been detected so far futurezone.de
futurezone.defuturezone.deOpen source ↗.
Upper limit on the stellar mass
To estimate how many stars the object might contain, the team simulated galaxies of different sizes and stellar masses and checked whether they would be visible in the available images. This gave an estimated upper limit of about 50 million solar masses in stars futurezone.de
futurezone.defuturezone.deOpen source ↗. On that basis, AGC 322753 could hold at least 40 times more neutral hydrogen than stars, which makes it an unusual dark-galaxy candidate
futurezone.de
futurezone.defuturezone.deOpen source ↗.
The gas may also have a different origin: it could come from gravitational interactions with neighbouring galaxies. This explanation has not been ruled out, even though the nearest known neighbour is far away futurezone.de
futurezone.defuturezone.deOpen source ↗. Further observations are meant to show whether the object is really a dark galaxy without a significant stellar population.
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