The cosmic violence of a black hole tearing apart a star produced a brilliant burst of radio light, which has been observed by astronomers thanks to a new international collaboration.

The U.S. National Science Foundation’s Very Large Array (NSF VLA) captured an off-axis afterglow that the researchers believe was left behind by a powerful jet produced by the star’s destruction. The black hole event was dubbed AT2019ijn by the Chinese research team that made the observation using U.S. equipment, and was described in a recent paper published in The Astrophysical Journal Letters.

Intriguingly, this explosive cosmic event provides astronomers with important new clues in the search for some of the universe’s rarest types of black holes.

A Bright Blue Flash

Various optical surveys of the cosmos detected the bright blue flash of AT2019ijn. For a few days, it continued to grow in brilliance before oddly fading at a rate far slower than is typical of similar transients.

Yet the optical spectrum did not tell the full story. As researchers combed through radio observations, they unexpectedly discovered that the radio emission did not peak within mere days but continued growing for two years before decaying over the next four. Also notable was the intensity of the emission, which was far more luminous than is typically seen during these phases of a stellar explosion.

Its 3-gigahertz luminosity was more than 100 times greater than signals typically observed from supernovae or fast blue optical transients.

Understanding the event required researchers to combine optical data with radio observations from the NSF VLA, India’s Giant Metrewave Radio Telescope, and Australia’s ASKAP. By expanding their radio view with these various facilities, the researchers were able to observe how the event changed over time, allowing them to develop and test various models.

A Black Hole Explanation

The Chinese astronomers identified a black hole as the most likely cause of these strange observations. Their focus was on a tidal disruption event, which occurs when a star wanders too close to a black hole and is torn apart by the incredibly powerful gravitational forces it encounters. Intriguingly, the researchers found that an event matching the observed optical brightness would require an extremely rare class of black hole.

Black holes are among the most extreme objects in the universe and tend to occupy opposite ends of a mass spectrum. The smaller variety is known as a “stellar-mass” black hole, since these objects form from the collapse of stars. At the other end are supermassive black holes, which anchor entire galaxies. However, intermediate-mass black holes have largely eluded astronomers, partly because their presence can be difficult to detect.

Detecting Intermediate-Mass Black Holes

Crucially, AT2019ijn allowed researchers to identify a new avenue for detecting these rare black holes.

Perspective is important in these detections. When an intermediate-mass black hole’s jet is not aimed directly toward Earth, the event may appear far less intense at optical wavelengths than expected. However, continued observation at radio wavelengths can reveal a much more intense afterglow as the jet evolves. This delayed brightening could therefore provide an important new clue for identifying potential intermediate-mass black holes.

Looking more broadly, the astronomers contend that many extreme black hole events may be missed because observations cease after the initial optical flash, leaving potentially intense radio peaks unobserved. As even more advanced observational platforms come online, such as the upcoming Next Generation Very Large Array, future radio surveys may reveal more such events, potentially illuminating a previously unrecognized class of transients similar to AT2019ijn.

The paper, “AT2019ijn: A Fast-rising, Slow-decaying Blue Optical Transient with Exceptionally Bright Radio Emission,” appeared in Astrophysical Journal Letters on July 6, 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.

A key component of the Orion Nebula had escaped detection by astronomers until now, according to a new study in Astronomy & Astrophysics.

An international team led by Juan Diego Soler at the University of Vienna used two of the world’s most advanced radio telescopes to map neutral atomic hydrogen gas across the nebula’s outer shell at unprecedented resolution. The new maps provide a clearer view of the celestial feature, and reveal a previously uncatalogued second bubble—a shell with much less mass than earlier estimates—and a four-light-year filament of gas extending from the structure.

The Orion Nebula’s Miscalculated Bubble

Neutral hydrogen emits a faint radio signal at a wavelength of 21 centimeters, making it possible to trace otherwise invisible gas between the stars. Soler’s team solved this by combining data from the Karl G. Jansky Very Large Array in New Mexico and the FAST telescope in China. The VLA provided high resolution, while FAST picked up faint, widespread signals. Together, they produced the first detailed hydrogen map of the extended Orion Nebula, at the same scale as earlier ionized carbon maps.

Earlier calculations based on ionized carbon estimated that the front half of the shell was about 1,100 times the mass of our Sun. The hydrogen observations paint a different picture, suggesting the shell actually weighs in at closer to 100 solar masses. “Measuring mass is fundamental,” Soler said, “because it tells us about the efficiency of these newly formed stars shaping their environment with wind and radiation.”

A shell with only a tenth of the previously assumed mass significantly alters calculations of how efficiently newly formed stars shape their environment. The researchers note that molecular hydrogen, which is not detected in either the hydrogen or carbon data, may account for some of the missing mass.

A Second Bubble

The hydrogen maps also revealed an uneven distribution of gas, indicating a second, smaller cavity within the main shell. The team searched catalogs of known stars and young stellar objects in the region but found no candidate at the bubble’s center. The source responsible for creating the cavity may not be the type of object included in current catalogs.

Daniel Seifried at the University of Cologne, a co-author on the study, pointed to what that means for the models astronomers build to explain regions like this one. “These stunning observations serve as a reference for many modern astrophysical simulations investigating the evolution of gas and stars in the Milky Way. These are the kind of images that challenge the theoretical models and numerical simulations that we use to understand how massive stars affect their immediate surroundings.”

Previous models generally treated Orion’s shell as the product of a single expanding bubble. The discovery of a second cavity, with no obvious source at its center, instead suggests the nebula was shaped by multiple episodes of stellar feedback.

An Unexpected Filament

The new maps also uncovered a filament of hydrogen extending about four light-years from the shell’s western edge. Previous carbon-based observations saw only the base of this structure. The filament contains about 80 solar masses of hydrogen and does not appear to be associated with any known group of young stars. Its origin is unclear; it could be gas leaking through a weak spot in the shell or a leftover from the original cloud that existed before the bubble formed.

Claire Murray of the Space Telescope Science Institute, another co-author, framed the discovery within the broader push behind the observations. “This study is an exciting demonstration of the power of the latest-generation radio telescopes to uncover new pieces to the star formation puzzle.” Despite being one of the galaxy’s most extensively studied star-forming regions, the Orion Nebula continues to reveal discoveries.

This survey is the first scientific result from the NeAtHood project, which aims to map atomic hydrogen across nearby star-forming regions accessible to the VLA and FAST telescopes. Soler and his colleagues now plan to apply the same approach to additional targets. “Orion is only the beginning. Our newly developed methods show how future interferometers will reveal the hidden structure and dynamics of the interstellar medium—even in regions that astronomers already believed they understood well,” Soler explained.

If one of the sky’s best-studied star-forming regions still contains hidden structures, other nearby nebulae may prove equally surprising as the NeAtHood survey expands.

Austin Burgess is a writer and researcher with a background in sales, marketing, and data analytics. He holds an MBA, a Bachelor of Science in Business Administration, and a data analytics certification. His work focuses on breaking scientific developments, with an emphasis on emerging biology, cognitive neuroscience, and archaeological discoveries.