Observations by NASA’s James Webb Space Telescope (JWST) have led to the surprising discovery that an ancient, distant galaxy is not rotating as expected, adding to our knowledge of the diverse conditions of the early universe.

The recent JWST finding was especially unusual because similar behavior has been observed only in nearby, mature, massive galaxies whose star formation slowed gradually over billions of years.

A team of researchers estimates that the galaxy XMM-VID1-2075 is not even 2 billion years old, based on the JWST observations, compared to the Milky Way’s 13.6 billion years, making its behavior highly unusual, according to their recent paper published in Nature Astronomy.

Rotating Galaxies

“This one in particular did not show any evidence of rotation, which was surprising and very interesting,” said lead author Ben Forrest, a research scientist in the Department of Physics and Astronomy at the University of California, Davis.

As gas flowed into early galaxies, most astronomers believe that angular momentum, combined with gravity, caused them to spin. However, over long periods of time, galaxies can lose their initial spin through mergers rather than spins canceling one another out. 

Because of this, we would expect to see this lack of spin primarily in galaxies close to Earth, as the distance light has traveled would be shorter, and therefore the light would come from older, more mature galaxies that have had the opportunity to experience such mergers. Finding a galaxy so distant, and therefore so young based on the speed of the light, is most unexpected.

James Webb Space Telescope Survey

The research was part of the MAGAZ3NE (Massive Ancient Galaxies at z>3 NEar-Infrared) survey on the JWST by researchers who had used Hawaii’s W.M. Keck observatory to observe XMM-VID1-2075 previously.

“Previous MAGAZ3NE observations had confirmed this was one of the most massive galaxies in the early universe, with already several times as many stars as our Milky Way, and also confirmed that it was no longer forming new stars, making it a compelling target for follow-up observations,” Forrest said.

Using the JWST’s advanced capabilities, the researchers compared XMM-VID1-2075 with two galaxies of similar age to measure their relative motion.

“This type of work has been done a lot with nearby galaxies because they’re closer and larger and so you can do these kinds of studies from the ground, but it’s very difficult to do with high redshift galaxies because they appear a lot smaller in the sky,” Forrest said. “(JWST) is really pushing the frontier for these kinds of studies.”

JWST DATA Reveals an Unusual Galaxy

The JWST data on the three galaxies yield a strange combination of results: one rotates as expected, another is described as “messy,” and the last does not rotate but exhibits significant random movement. While this behavior is expected of massive galaxies in our local neighborhood, the researchers were stunned to find it occurring so close to the beginning of the universe.

The team leans toward one possibility that may offer an explanation, suggesting that a kind of equilibrium was achieved when two galaxies with almost perfectly opposite rotations collided in a single event.

“For this particular galaxy, we see a large excess of light off to the side. And so that’s suggestive of some other object which has come in and is interacting with the system and potentially changing its dynamics,” Forrest said.

Continuing their work, the team will seek other early galaxies lacking spin and explore galaxy-formation simulations that could explain this behavior.

“There are some simulations that predict that there will be a very small number of these non-rotating galaxies very early in the universe, but they expect them to be quite rare,” Forrest concluded. “And so this is one way in which we can test these simulations and really figure out how common they are, and that can then give us information about whether our theories of this evolution are correct.”

The paper, “A Massive and Evolved Slow-Rotating Galaxy in the Early Universe,” appeared in Nature Astronomy on May 04, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.

Stars are mostly made of 2 elements: hydrogen and helium. While this has always been the case, those 2 elements and lithium were the only elements in existence when the Big Bang occurred around 14 billion years ago. When the first stars exploded, they released those primordial elements, as well as heavier elements produced by nuclear fusion inside them. 

Astronomers call all elements heavier than hydrogen and helium metals, a term chemists use quite differently. Subsequent generations of stars, including the Sun, formed in clouds of gas and dust enriched with these metals, such as carbon, oxygen, magnesium, and silicon. Scientists estimate that modern stars are 1% to 5% metal by mass.

Astronomers claim there is no solid evidence that stars contain exceptionally high amounts of metals, but some, called chemically peculiar stars, appear to. Astronomers study stars by looking at the patterns of light they emit, called spectra. Each element produces a unique light pattern, so astronomers can compare the light patterns in a star’s spectra to determine how much of each element is present, especially in the outer layers of the star. Researchers theorize that chemically peculiar stars don’t actually have more metals than average stars. Instead, they think that metals from their interiors diffuse to their outer layers more than in most stars.

A team of researchers from the American Association of Variable Star Observers and Masaryk University in Czechia recently observed 85 chemically peculiar stars to understand their behavior and better classify them. For their study, they first used the General Catalog of CP Stars, published in 2009 in Astronomy & Astrophysics, to identify targets across the 4 classes of these stars, labeled CP1 through CP4. CP1 stars have strong spectral patterns for iron and other heavy elements, CP2 stars have strong patterns for silicon, chromium, strontium, and europium, CP3 stars have strong patterns for mercury and manganese, and CP4 stars have either unusually weak or usually strong helium patterns. 

The team compiled a list of 85 stars to observe, then used the BRIght Target Explorer (BRITE) Constellation to monitor changes in their brightness. The BRITE Constellation is a set of 5 satellites equipped with telescopes and cameras for either red or blue light. Using the BRITE Constellation, the team monitored each star for several days. 

They found that 74 of these 85 chemically peculiar stars varied in brightness during their survey. They attributed this to the varied abundance of metals on their surfaces, which would form dark patches that go in and out of view from Earth’s perspective as the stars rotate. The team observed that 6 of these 74 stars appeared to change in brightness over multiple periods. They were surprised by this result because a star’s brightness wouldn’t vary over multiple periods if the changes were due to rotation. They compared their findings to data other scientists had collected from these stars with the Transiting Exoplanet Survey Satellite, or TESS, and found that all 6 stars had been misclassified as chemically peculiar stars.

The other 11 chemically peculiar stars appeared to show no periodic changes in their brightness, suggesting that they’re stationary. The team claimed that some CP1 and CP3 stars don’t rotate, but they identified cases in which CP2 and CP4 stars that ought to rotate appeared to be stationary. They suggested 2 potential reasons for this. One is that these CP2 and CP4 stars are misclassified, requiring more thorough analysis of their spectra to confirm their classifications. The other is that the stars rotate slowly, with rotational periods of 50 days or longer, which would be difficult to distinguish from those of totally stationary stars.

The team concluded that more astronomers should revisit the historical classifications of stars, especially as technology advances and more space-based telescopes become available. This strategy would allow future researchers to draw better data from research archives and catalogs. Additionally, they claimed that their method of pairing long-term monitoring via small satellites with TESS data is well-suited for refining classifications, identifying misclassified objects, and further exploring the structure and mechanics of chemically peculiar stars.

The post What makes ‘chemically peculiar stars’ peculiar? appeared first on Sciworthy.