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JWST Spies Once-hidden Treasures in the W51 Starbirth Crèche

Star formation is a dramatic and complex process that erupts throughout the Universe. Yet, a lot of that action gets hidden by clouds of gas and dust. That’s where observatories such as the James Webb Telescope JWST and the Atacama Large Millimeter Array (ALMA) come in handy. They use infrared light and radio waves respectively, to pierce the veil surrounding the process of starbirth.

A team led by University of Florida doctoral candidate Taehwa Yoo recently used to JWST to make observations of the giant Milky Way starbirth region Westerhout 51 (W51). It lies about 17,000 light-years away from Earth in the direction of the constellation Sagittarius. The images and data they collected revealed many fine details of the star-formation activity going on there. “With optical and ground-based infrared telescopes, we can’t see through the dust to see the young stars,” said Adam Ginsburg, Ph.D., a professor of astronomy at UF. “Now we can.”

An overview of W51A region. The composite image is produced by combining NIRCam F360M (blue), F410M (green), and MIRI F560W (red) on JWST. The north and east directions in ICRS coordinates are marked as arrows at the upper left corner. Courtesy Yoo, et al.

Despite the impressive images and data, some aspects of star birth remain hidden away behind clouds too dense even for JWST to pierce. The team compared their JWST images to observations of the same region made by the ALMA, and found that only a fraction of stars are detectable by both telescopes. The observations that JWST did make, however, showed a lot of detail in the structures it could see. And that provides astronomers with new insights into the starbirth process. “Because of James Webb, we can see those hidden, young massive stars forming in this star-forming region,” Yoo said. “By looking at them, we can study their formation mechanisms.”

Digging Into W51’s Starbirth Activity

Cutout images of specific regions in W51. (a) A dust filament around W51-E. (b) W51-IRS2 protocluster. (c) Cometary objects around W51-IRS2 (these are globules of dust that look like comets, sculpted by radiation from nearby stars). (d) W51-E protocluster. (e) A bar at the edge of IRS1 H II region. (An HII region is a cloud of mostly hydrogen gas from which stars can form.) (f) W51 IRS1 H II region shell structure. (g) W51b1 H II region. (h) W51b2 H II region and YSOs. (i) W51e7 H II region. (j) W51c1 H II region. (k) and (l) Newly discovered H II regions. Courtesy Yoo, et al.

W51 is divided into several regions of enhanced star formation. As part of the observations, JWST zeroed in on the W51A region, the youngest starbirth crèche in the area. Multiple clouds of ionized gas and warm dust exist there, with some of the dust arranged in filaments. The science team also spotted a good example of a cavity around one of the newborn stars, which indicates that the star is “eating away” at its birthplace. They also studied giant gas bubbles of gas, dark dust filaments (which are likely still-hidden crèches), cometary objects, and protostellar jets streaming away from protostellar objects. Each of these are part of the starbirth process.

The team focused on the massive protoclusters called W51-E and W51-IRS2, using the Near Infrared Camera (NIRCAM) and the Mid-infrared Instrument (MIRI). Most of the stars they were able to observe are still accreting material and hadn’t yet reached their full masses. Some have only formed in the past million years or so.

Yoo’s group estimates there are about 10,000 solar masses of stars in W51A. Many are very young, massive stars, and not a lot is known about their earliest infancy, which is what fascinates astronomers today. In some areas, those remain hidden by too-thick clouds of gas and dust. Luckily, W51A has a lot to offer based on previous studies made by the Atacama Large Millimeter/submillimeter Array (ALMA). That radio array in Chile detected over 200 compact sources referred to as “PPOs (Pre/Protostellar Objects)” in the region. These are places where stars are actively forming or will start to form in the relatively near future. Astronomers want to know what kickstarts the process of star formation in regions like these, and what stages occur as massive young stars begin to form.

Combined observations from JWST and ALMA show the location of protocluster regions where multiple stars are forming. The locations of the matching sources are marked in the upper panel with the background image of F162M, F210M, and F480M filters on JWST. In the lower panels, W51-E and W51-IRS2 protocluster regions are zoomed in with the background image of the JWST NIRCam filters and ALMA 1.3 mm image combined. Courtesy Yoo, et al.

Starbirth Stages

In a general sense, astronomers know the overall process of starbirth: clouds of gas and dust condense and form hot cores called “young stellar objects.” These are where the future star will be born. After a period of accretion, the star reaches a point where it begins fusing hydrogen to helium in its core. That’s the point where the star is born. Before that, the star begins as that hot core, and also blows material away from itself via a superheated jet. High-mass stars born like this obviously affect their environment, especially in their birth crèches. They interact with neighboring clouds of gas, which affects the formation of sibling stars in the same region. The radiation from those high-mass stars can even go so far as to rip apart the clouds of gas. That chokes off the available material for new stars to form. From the JWST images and data, it’s clear that each of those steps is in process in the W51A cloud.

In a recent paper in the Astrophysical Journal (noted below), Yoo and the team point out that several hot cores with rich chemistry associated with massive protostars exist in W51A. These are very likely sites of maser emissions from several varieties of molecules in the gas clouds crèches, including OH (hydroxide), CH₃OH (methanol), SiO (silicon monoxide), NH₃ (ammonia), and CS (carbon monosulfide). The presence of these masers acts as a tracer for dense molecular clouds where stars are expected to form (if they aren’t doing so already).

In addition to the hot cores that indicate the very early stellar birth process, the team also observed at least one “knot” of emission from a protostellar object. It indicates ionized iron and hydrogen within the cloud. They think it’s from a jet streaming from a hot young star that’s heating up and affecting the nearby interstellar medium.

This latest look at W51 with JWST gives astronomers a much better idea of what different stages of starbirth look like, stages that are normally hidden from optical observations. The quality of the JWST data revealed more information and showed new structures in the area that astronomers can now use to more fully explain the process of starbirth. “They are not the first photos of this region, but they are the best,” said Ginsburg. “They’re so much better that they essentially are brand new photos. Every time we look at these images, we learn something new and unexpected.”

For More Information

Researchers Use JWST to Reveal Hidden Details of W51 Star Formation

A JWST NIRCam/MIRI view of the W51A high-mass star-forming region

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A Long Island Rail Road Strike May Be Near. Here’s What to Know.

America’s busiest passenger rail service will shut down on Saturday if workers and transit officials cannot agree on a new contract.

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Dark Matter May Have Left Its Fingerprint in a Gravitational Wave.

A Horseshoe Einstein Ring from Hubble 1 20260515 070108

Dark matter is everywhere. It accounts for the vast majority of matter in the universe, yet it has no interaction with light, magnetism, or any other force along the electromagnetic spectrum. It passes through everything, through planets, through stars and even through you without leaving a trace. One of the only ways we know it exists at all is through the way it bends space around distant galaxies, adding extra pull that ordinary matter alone cannot explain.

Finding direct evidence of dark matter has been one of the great unsolved challenges of modern physics. Now a team led by MIT postdoctoral physicist Josu Aurrekoetxea has proposed a new and unexpected way to look for it, not by building detectors on Earth, but by reading the gravitational waves that arrive from black hole mergers across the universe.

The rotation rate of spiral galaxies (such as M77 captured here) is just one of the ways that dark matter reveals itself (Credit : NASA/ESA)

The idea hinges on a remarkable phenomenon called superradiance. The idea is that dark matter consists of extraordinarily light particles, many orders of magnitude lighter than an electron and that behave not just as individual particles but as coordinated waves when they encounter a rapidly spinning black hole. When those waves brush against a spinning black hole, the black hole’s own rotational energy transfers to the dark matter, amplifying it to extreme densities. The researchers describe it as like churning cream into butter, a diffuse ingredient concentrated into something far denser and more structured.

This process creates a thick dark matter cloud swirling around the black hole. When a second black hole spirals in to merge with it, it passes through that cloud. The interaction leaves a distinctive imprint on the gravitational waves produced by the merger, a subtle but specific pattern that differs from a merger in empty space.

The MIT team built a model that predicts exactly what that imprint should look like, then applied it to publicly available data from the LIGO, Virgo and KAGRA gravitational wave observatories, screening 28 of the clearest signals from their first three observing runs.

“We know that dark matter is around us. It just has to be dense enough for us to see its effects. Black holes provide a mechanism to enhance this density, which we can now search for by analysing the gravitational waves emitted when they merge,” – Josu Aurrekoetxea from MIT

Twenty seven showed exactly what you’d expect from black holes merging in a vacuum. But the twenty eighth, a signal catalogued as GW190728, showed something different. A pattern consistent with dark matter involvement.

LIGO Hanford Observatory (Credit : LIGO Observatory)

The team are careful to stop short of claiming a detection, since this is a hint and not a confirmation. But it is the first time a gravitational wave signal has been flagged as a candidate dark matter imprint using a rigorous physical model, and it demonstrates that the technique works.

LIGO’s fourth and fifth observing runs are generating gravitational wave detections at an unprecedented rate. Each new signal is another opportunity to screen for the fingerprint. If the team are right, dark matter has been hiding in plain sight for decades and we may finally have found a way to catch it.

Source : A new way to spot signs of dark matter

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Dodgers pitcher, horse racing jockeys linked to cockfighting in Puerto Rico

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A Los Angeles Dodgers pitcher and two of the top jockeys in horse racing were allegedly linked to illegal cockfighting in Puerto Rico through social media posts, according to reporting from USA Today.

The article, published Thursday, highlights social media posts advertising cockfighting tournaments that picture three-time All-Star closer Edwin Díaz in his Dodgers uniform and an article in El Nuevo Día, the largest circulating newspaper in Puerto Rico, quoting Díaz.

Brothers and jockeys Jose Ortiz and Irad Ortiz, who finished first and second, respectively, in the Kentucky Derby this month were advertised as participants in a cockfighting tournament in 2025, according to the outlet.

Representatives for Díaz and the Ortiz brothers did not immediately respond to requests for comment on Thursday. Diaz and the Ortiz brothers were born in Puerto Rico where cockfighting has been a longstanding cultural tradition, a massive industry and a source of tension between the U.S. territory and the federal government.

In 2019, a federal law banning cockfighting took effect in Puerto Rico. Before the law, the blood sport had been made illegal in all 50 states, but not U.S. territories. Many Puerto Ricans saw the ban as an attack on their culture and vowed to defy the law.

Puerto Rico responded by passing a law saying that it’s legal to host cockfights as long as people don’t export or import the animals or any goods or services related to cockfighting. The U.S. Supreme Court in 2021 declined to hear a challenge to the federal law brought by a group that argued Congress exceeded its power by applying the ban to Puerto Rico.

In the El Nuevo Día story, which published in March, Díaz is quoted talking about cockfighting, saying it was a pastime he’d followed since he was a child. He was attending a tournament in which his family entered four roosters, according to the article.

“It’s legal in Puerto Rico, thank God. Otherwise, I wouldn’t be here,” he said in Spanish. “It’s something I’ve done since childhood, something my dad instilled in me.”

The Dodgers signed Díaz to a three-year, $69-million contract in December 2025. Last month, the team announced that Díaz was having surgery to remove “loose bodies” in his right elbow and would be out until the second half of the season.

A Facebook post by Club Gallistico de Puerto Rico on Dec. 17, 2025, pictures the Ortiz brothers and lists them as participants in a cockfighting event. The post, which is in Spanish, notes that the brothers excel in international horse racing, but also have a passion for cockfighting.

“Brothers Irad and José Luis Ortiz accepted the challenge of participating in the ‘Caribbean Grand Champion’ tournament with a single goal: to become undisputed champions,” the post read in Spanish.

Kentucky Horse Racing and Gaming, which is charged with regulating horse racing, launched an investigation after receiving reports that Irad Ortiz and Jose Ortiz were participating in a cockfighting event, Travers Manley, the senior vice president of gaming and media relations for the organization, wrote in a statement to The Times. It is not clear when the investigation specifically began.

“The investigation included the stewards meeting with Irad and Jose. Following the investigation, KHRG stewards elected not to take administrative action against them,” Manley wrote.