The ‘red potato’ galaxy discovered by the James Webb telescope

Galaxy MQN01 J004131.9-493704

doi.org/10.48550/arXiv.2601.20473
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Astronomers from several countries, led by Weichen Wang of the University of Milan, Italy, have just identified a very special and surprising galaxy in the distant universe

Using the powerful James Webb Space Telescope (James Webb), they found a massive, red galaxy that is practically “stopped” in terms of star formation, affectionately nicknamed “Red Potato” because of its rounded shape and characteristic reddish color.

The discovery happened by chance while the team was investigating a gas-rich region called MQN01, which is located at an enormous distance-about 11.5 billion light-years from Earth (corresponding to a redshift of approximately 3.25).

This type of place, known as a knot in the cosmic web or protocluster, is usually full of cold, molecular gas, which favors the accelerated creation of stars and the growth of large galaxies.

Therefore, scientists expected to see a lot of star formation activity there.

However, at the center of this gaseous region, the telescope revealed something unexpected: a giant galaxy, with a mass of about 110 billion times the mass of the Sun and an approximate diameter of 6,500 light-years (measured at half the speed of light), but which practically no longer forms new stars.

Its star formation rate is extremely low, only about 4 solar masses per year-a value much lower than what would be normal for such a dense galaxy located in such a material-rich environment.

Astronomers noted that the “Red Potato” has very little molecular gas (less than 7 billion solar masses) and also almost no neutral gas.

No winds or gas outflows were detected from it, and the movements of the ionized gas indicate that it is a velocity-dispersion-dominated system, that is, quite turbulent.

What makes the case even more intriguing is that, despite being immersed in a large reservoir of cold gas around it (visible from Ly? and H? emissions), the galaxy is not using this material to produce stars.

Researchers believe that a jet of X-rays from a nearby active galactic nucleus (AGN) is influencing the environment.

This jet likely increases turbulence in the surrounding gas (the so-called circumgalactic medium), making it difficult for gas to calmly fall into the galaxy and form new stars.

In short, the “Red Potato” is a fascinating example of how a very massive galaxy can “retire” early, becoming quiescent (or “dead” in terms of star formation), even while being in the middle of an “ocean” of gas that, in theory, should feed it.

This discovery, reported in an article on the arXiv repository, raises new questions about the mechanisms that turn off star formation in the early universe and shows how the James Webb Space Telescope continues to reveal surprises about how galaxies evolve in the first billion years of the cosmos.

Published in 02/09/2026 09h46

Portuguese version

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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