doi.org/10.48550/arXiv.2507.13014
Credibility: 888
#PunctumÂ
An extremely bright and mysterious object discovered in a nearby galaxy is perplexing astronomers
Called *Punctum*, which means “point” in Latin, it was found by a team led by Elena Shablovinskaia of the Institute of Astrophysical Studies at Diego Portales University in Chile.
The object is so unlike anything ever seen that it may represent a new category of phenomenon in space.
An Unexpected Discovery
*Punctum* was detected by the ALMA telescope in Chile, which observes the universe in millimeter radio waves.
It is located in the galaxy NGC 4945, about 11 million light-years from our Milky Way.
Despite being so close in cosmic terms, Punctum is only visible in millimeter waves, not in visible light or X-rays, which makes the mystery even greater.
So far, the James Webb Space Telescope (James Webb) has not observed the object in infrared light, but this may happen in the future.
“When we put it into perspective, Punctum is incredibly bright,” said Shablovinskaia.
It is 10,000 to 100,000 times brighter than magnetars (a type of neutron star with intense magnetic fields), 100 times brighter than microquasars (star systems with smaller black holes), and 10 to 100 times brighter than most known supernovae.
Only the Crab Nebula, the remnant of a supernova that exploded in 1054, outshines Punctum among stellar objects in our galaxy.
What Could *Punctum* Be?
Scientists still don’t know what *Punctum* is, but they do know it’s a compact object with a highly organized magnetic field that emits enormous amounts of energy.
It didn’t change brightness during several observations made in 2023, which rules out the possibility of it being something temporary, like a flare.
Typically, millimeter waves come from cool objects, such as dust disks where planets are being formed or gas clouds in space.
But very energetic phenomena, such as quasars (galaxy nuclei with supermassive black holes) or pulsars (rapidly rotating neutron stars), can also emit radio waves through a process called synchrotron radiation.
This occurs when charged particles, moving at nearly the speed of light, rotate around magnetic field lines.
*Punctum’s* light is strongly polarized, indicating a well-structured magnetic field, typical of compact objects.
Therefore, the team believes that synchrotron radiation could be the source of Punctum’s energy.
A magnetar, a pulsar with an extremely strong magnetic field, could be one possibility, but magnetars are much dimmer at millimeter wavelengths than Punctum.
Another possibility would be a supernova remnant, like the Crab Nebula, which is bright at millimeter wavelengths.
But these remnants are large, light-years across, while Punctum is clearly a small, compact object.
“At the moment, Punctum doesn’t really fit into any known category,” Shablovinskaia said.
“And honestly, nothing like it has turned up in previous searches because, until recently, we didn’t have a telescope as sensitive and high-resolution as ALMA.”
A Mystery to Be Unraveled
Punctum was discovered by chance while scientists were observing the bright nucleus of the galaxy NGC 4945. It is 100 times dimmer than the active nucleus of that galaxy, which is powered by a supermassive black hole, and might have gone unnoticed if not for its strong polarization.
New observations with ALMA, focused directly on Punctum, may help clarify its nature.
Observing it at different frequencies and with less interference from the galaxy’s bright nucleus could reveal more details.
Furthermore, the James Webb Telescope could be decisive: if it detects Punctum in infrared light, its high resolution could help identify whether the emission comes solely from synchrotron radiation or whether it involves dust or other materials.
For now, Punctum remains a true enigma.
It could be an extreme version of something we already know, like a magnetar in an unusual environment, or it could be the first example of a new type of object in space.
“In any case, Punctum shows us that there is still much to discover in the millimeter-wave sky,” Shablovinskaia concluded.
The Punctum study has been accepted for publication in the journal Astronomy & Astrophysics and is available as a preprint on astro.ph.
Published in 08/18/2025 09h20
Text adapted by AI (Grok) and translated via Google API in the English version. Images from public image libraries or credits in the caption. Information about DOI, author and institution can be found in the body of the article.
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