The subject of this NASA/ESA Hubble Space Telescope image is a spiral galaxy struggling against titanic forces that appear on galactic scales in space. This is NGC 4654, an intermediate spiral galaxy in the constellation Virgo (the Maiden). It is classified as an “intermediate” because its overall shape lies between spiral galaxies that have a bar across their centers and those that don’t. NGC 4654 has a weak bar structure at its center and is located 72 million light-years from Earth in the Virgo Cluster, a particularly massive and populous galaxy cluster.

NGC 4654 is particularly asymmetric, with a rounded and clearly-defined edge on one side and a long tail of gas stretching out from the opposite side — outside the field of view captured in this image. This gaseous tail is the result of ram pressure stripping, a force that galaxies can experience as they plow through space. NGC 4654 moves with such high velocity that it sweeps up and rams through the hot, rarefied gas filling the space between the Virgo Cluster’s galaxies. This intracluster medium in turn exerts a “ram pressure” on the galaxy, compressing the galaxy’s leading edge and dragging its gas behind the galaxy, creating the elongated tail.

It’s not just the galaxy’s gas that is unevenly distributed: its stars are too, and this is more unusual for a spiral galaxy. While the spiral arm on its leading edge is rich with stars and gas, the opposite arm noticeably lacks stars, influencing the galaxy’s lopsided spiral shape. Astronomers think that ram pressure alone is unlikely to cause this effect. Rather, NGC 4654 was also subjected to the gravitational force of fellow Virgo Cluster galaxy NGC 4639. While the two galaxies are far apart now, it’s thought that a fly-by interaction between them around 500 million years ago ripped away NGC 4654’s gas along one side, limiting star formation there and creating the asymmetry in its shape.

Many galaxies that undergo ram pressure stripping suffer reduced star formation rates as the cold gas that collapses to form their stars is pulled away and lost. NGC 4654, however, is still forming nearly two Suns’ worth of stars every year, a rate comparable to other galaxies of similar size. The active star formation is visible in the latest Hubble data included in this image. The data picks up on a wavelength of red light emitted by the clouds of energized gas where newborn stars lurk. The bright pink bubbles that appear across NGC 4654 — from its forward spiral arm, to around its weak bar, and out to the edge of its disk — are areas where these newborn stars shine.

The data used in this image came from two observing programs (#15654, #17502) that aim to link the gas in galaxies with star formation. By observing many prominent galaxies in the vicinity of our own, researchers hope to better understand how gas moves in galaxies, where and when it collapses to form stars and star clusters, and what effect those new stars have on the gas around them.

Text Credit: ESA/Hubble

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

Webb found a hidden giant planet by detecting its atmospheric chemistry through a bright debris disk. For years, a third giant planet remained concealed within the bright dust surrounding Beta Pictoris, one of the most closely observed planetary systems in the Milky Way. NASA’s James Webb Space Telescope has now exposed the hidden world by [...]

Il existe plusieurs objets et phénomènes exotiques en astrophysique qui sont des serpents de mer, comme on dit. Des signes de leur existence apparaissent parfois et à répétition dans les observations, sans que l'on puisse aboutir vraiment à une conclusion. C'est le cas avec une nouvelle...

The camera that checked JWST’s clock is losing its funding.

James Webb Space Telescope (JWST) observations have astronomers on the brink of solving another long-standing astronomical mystery: how do supermassive black holes feed?

Astronomers from the Université de Montréal led an international team in the new research, reported in a recent paper in The Astrophysical Journal, which presents the clearest images ever recorded of gaseous filaments connecting a galaxy’s atmosphere to the rotating disk that the supermassive black hole feeds on.

The team’s analysis of the data paves the way toward understanding how black holes consume matter, a mystery that has stumped astronomers for decades.

Strange Black Hole Feeding

“JWST observations are offering us thousands of new facts and measurements, and I can report it’s a lot to absorb,” said co-author Megan Donahue, MSU University Distinguished Professor of physics and astronomy. “We are all working together to solve the astrophysics questions about how these black holes get their fuel and how they interact with their host galaxy.”

Supermassive black holes anchor most galaxies in the universe, with masses ranging from millions to billions of times that of the Sun. In active galactic nuclei (AGN), these central black holes both consume enormous amounts of surrounding material and unleash powerful jets that shape the galaxies around them.

This activity presents a longstanding puzzle. Because an AGN’s jets heat the surrounding gas, they should effectively cut off the black hole’s fuel supply, leaving astronomers to wonder how it continues to accrete matter.

Testing a Hypothesis

To investigate, the researchers tested the leading explanation: that heated gas eventually cools, condenses into long filaments, and falls back toward the galactic center, replenishing the black hole’s supply of material.

They turned JWST toward one of the best natural laboratories for studying AGN: the galaxy NGC 4696, located at the heart of the Centaurus Cluster, roughly 145 million light-years from Earth.

Using JWST’s NIRSpec instrument, the team collected eight hours of observations, mapping the motion of gas deep within the galaxy—where the black hole’s gravitational influence dominates—at a resolution of about 30 light-years.

Their observations revealed an 800-light-year-wide disk of gas orbiting the supermassive black hole at roughly 600 kilometers per second. Connected to this rapidly rotating disk was a large infalling filament, funneling gas inward to feed the AGN.

Feeding Cycle of the Black Hole

The discovery fills in a crucial missing piece of the puzzle surrounding how supermassive black holes sustain themselves. The researchers propose that after the black hole injects energy into the surrounding gas, heating it, that material eventually cools and collapses into thin filaments stretching hundreds of thousands of light-years. Guided by magnetic fields, these filaments then fall toward the galaxy’s center, where they accumulate in the rotating accretion disk.

The team also ran a series of computer simulations based on this model and found that the predicted behavior closely matched what JWST observed. While additional observations will be needed to confirm the results, the findings provide strong support for the filament-feeding hypothesis.

“It’s been really exciting to participate in this project,” co-author Mark Voit, an MSU Physics and Astronomy Professor, said in a statement.

“Calculations done by our Michigan State group predict that magnetic fields should help feed the universe’s biggest black holes by channeling cool gas toward them, and it’s amazing to see that happening in these JWST images,” he added.

The paper, “JWST Reveals How Lack Holes Are Fed: Kiloparsec-Scale Multiphase Filaments Feed Sub-Kiloparsec Circumnuclear Disks,” appeared in The Astrophysical Journal Letters on July 14, 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.

NASA’s James Webb Space Telescope (JWST) is celebrating four years of unexpectedly strong performance by providing a deep new view into one of the universe’s most familiar galaxies: Centaurus A.

Typically, Centaurus A’s thick dust obscures astronomers’ attempts to peer into it, yet the JWST’s near- and mid-infrared sensitivity allows scientists to see more of the galaxy than ever before. 

In new images released by NASA to celebrate JWST’s four years of impressive discoveries, the most powerful telescope ever constructed reveals the dense collection of stars that make up the ever-changing Centaurus A galaxy.

Inside Centaurus A

Due to two crucial factors, Centaurus A is an extremely interesting galaxy for astronomers. It is highly active, offering an important opportunity to monitor galaxy and black hole growth while being relatively close by, at just 11 million light-years away—a highly unusual combination.

The history of imaging Centaurus A is marked by questions, which JWST has now begun to answer. Webb’s predecessor, Hubble, could only view visible light in its examinations, leaving the galaxy’s central regions obscured by dust. Additionally, the Spitzer Space Telescope lacked sufficient resolution to resolve individual stars in infrared, although the data it collected provided new discoveries of massive dust structures.

Powerful events are on display in Centaurus A, the aftermath of a collision with another galaxy and a supermassive black hole’s active feeding. As the black hole releases powerful jets and gushes energy, it shapes the surrounding galaxy, which still retains an unusual shape left by its two-billion-year-old merger.

“No single telescope tells the whole story,” said Shawn Domagal-Goldman, division director, Astrophysics, NASA Headquarters in Washington. “Discoveries build over time, and new observatories expand on the foundations laid by earlier missions. Webb represents the most powerful step forward yet, opening a window into wavelengths and details never before accessible. This allows astronomers to examine structures and processes that other telescopes could not see.”

JWST Reveals Amazing Structures

Thanks to JWST’s mid-infrared capabilities, astronomers captured detailed images of Centaurus A’s dust structures and were surprised and confused by the glowing shapes revealed. One unusual feature is a band cutting across the galactic center, shaped like a warped parallelogram, with wispy tendrils stretching out of it.

Another feature, shaped like the letter “S,” also confounds astronomers, leaving many questions about the influence of both the central black hole and the galactic merger on its shape and evolution. 

A large portion of the red glowing dots in the image above represent dusty areas, either dust-rich stars or stellar nurseries, both important sources of dust for star formation, and therefore, the continuance of the galaxy.

Single Stars and JWST

The JWST’s incredible resolution is allowing astronomers to study the galaxy star by star for the first time. Combining images from the MIRI (Mid-Infrared Instrument) and the NIRCam (Near-Infrared Camera) revealed tightly packed individual stars.

This view of individual stars is essential for what some astronomers call “galactic archaeology,” by providing important clues that help scientists reconstruct the galaxy’s formation and evolution. This galactic timeline is made up of many important pieces revealed by individual stars, such as when the oldest stars formed, when star formation slowed, when the merger reignited a powerful burst of star formation, and how that collision stirred the galaxy’s gases, further accelerating star formation.

Capturing these details requires spectroscopy, a technique where light is broken down to reveal detailed information about distant stars. Also using this technique, researchers can gain important information about the central black hole, identifying that it can both compress gas to accelerate star formation and push gas away to limit it.

On its fourth anniversary, the unprecedented details now revealed about one of our most interesting galactic neighbors continue to underscore the JWST’s incredible promise as NASA’s premier space observatory.

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.

James Webb Space Telescope (JWST) observations have revealed that the fate of planets after the death of their host star may be surprisingly warm, according to new research from the University of St Andrews.

The JWST observations offer a possible glimpse into what our solar system will be like billions of years from now, particularly for gas giants like Jupiter. In a recent paper published in Nature, the St Andrew researchers describe JWST observations of WD 1856 b, a Jupiter-sized exoplanet much warmer than would be expected for orbiting a dead white dwarf star.

Webb Observes WD 1856 b

A collaboration between NASA, the European Space Agency, and the Canadian Space Agency, the JWST has provided an unprecedented view of the distant edges of the universe, revealing many unexpected finds. Among these surprises was WD 1856 b, whose mass, temperature, and atmosphere readings reveal a surprisingly intact planet after the death of its star.

Our own Sun is projected to exhaust its supply of hydrogen in roughly five billion years, after which it will expand into a red giant star about 100 times larger than it is today, before shedding mass in its final transformation into a white dwarf star.

In the distant future, the Sun’s transformations will likely someday obliterate Mercury, Venus, and even Earth, yet scientists have remained uncertain about how more distant planets will fare. Only by observing real-world examples of planets orbiting dead stars can scientists gather more data on how these scenarios play out for the remaining planets, as with JWST’s observations of WD 1856 b.

A Strange System

Discovered in 2020 by the TESS survey and the Spitzer space telescope, WD 1856 b orbits the white dwarf star WD 1856+534 at a distance of around 80 light-years from Earth.

“The planet is quite the oddball. It’s about the size of Jupiter, but the white dwarf it orbits is the size of Earth, so the planet is seven times larger than its star,” said lead author Dr. Ryan MacDonald from the University of St Andrews.

Perhaps the most confounding element of this system is how close the exoplanet is to its host star. At a distance of 50 times closer than the Earth is to the Sun, the planet is at a distance at which the star’s red giant phase should have destroyed it. How the planet managed to escape the destruction while ultimately ending up so close to its star intrigued the St. Andrews team.

James Webb Space Telescope Data

As WD 1856 b performed a grazing transit, where just its top edge passed in front of the host star, JWST observations allowed the researchers to crucially measure mass and temperature data, allowing them to estimate its mass at between four and eleven times that of Jupiter.

“We’re used to looking back in time when we use telescopes, but this is the first time we have been able to look forward to what might happen to the outer planets around the remnant of a Sun-like star,” MacDonald said, adding that “it’s like using a time machine to peer into the distant future of our Solar System.”

Infrared light emitted by the planet’s own heat showed a surprising temperature of 126°C, which is 240°C hotter than it would be from the white dwarf’s heat alone.

JWST Tells The Future

As the team worked on the problem, the temperature mystery proved to be the answer to the distance issue.

“The big question is how WD 1856 b ended up where it is today, and there are two theories. One is that the planet was swallowed by the host star as it was dying, and managed to survive on the inside,” said Dr. Christopher O’Connor of Northwestern University. “The other is that the migration took place due to the gravitational effect of other objects in the system. The white dwarf is part of a triple star system, and the outer companion stars could have influenced WD 1856 b’s orbit.”

Since no present source of energy should be capable of generating this much heat on the exoplanet, the researchers suggest that it represents heat left over from being engulfed by the red giant or possibly through an inward migration. Cooling models the team analyzed indicated that the planet likely first captured heat about 3 to 3.5 billion years ago, then cooled to its present temperature and migrated closer to its host star.

“This is just the beginning of our exploration of planets orbiting dead stars with Webb, and the search for further planets orbiting white dwarfs is ongoing,” Dr. MacDonald concluded. “Our results show that stellar death is not the end – some planets experience a vibrant and lively future after the death of their star.”

The paper, “Aerosol and Hydrocarbons in the Atmosphere of a White Dwarf Planet,” appeared in Nature on July 1, 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.

Webb found the same unexplained infrared fingerprint on two frozen worlds.

Researchers have identified the most distant dormant black hole known, dating back to the universe’s early history. Astronomers have long relied on brilliant quasars, supermassive black holes actively feeding on surrounding matter, to study the early universe. Yet these luminous objects reveal only part of the story. Now, researchers have detected the most distant dormant [...]

Newly published research made possible by NASA’s James Webb Space Telescope has revealed surprising insights into the mysterious interstellar comet 3I/ATLAS.

The findings, which stem from observations of the space visitor as it was leaving our Solar System months ago, reveal new clues to the ancient object’s origins, thanks to detailed new measurements of its chemistry.

Following its trip around the Sun late last year, 3I/ATLAS had been significantly warmed, causing a large amount of its icy exterior to be converted into a cloudy coma. This not only made the comet more visible but also provided Webb an ideal opportunity to collect spectrographic data that could offer important information about its chemical composition.

The Webb data, which was detailed in a recent study, indicates chemical ratios of carbon and deuterium emanating from the object that are very unlike those of comets found within our solar system.

The compelling new findings, according to NASA officials, “surprised researchers.” Here’s why.

A Rare Look at an Ancient Space Object

Fundamentally, the recent Webb observations provided astronomers with one of their best opportunities to observe information about the comet’s possible origins throughout the duration of its visit to our Solar System last year.

Martin Cordiner, an astro-chemist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, called the observations “a unique opportunity to study an ancient object from the distant galaxy, probably pre-dating our Sun and solar system.”

Cordiner, who was also the lead author of the recent Nature study, said that the data he and his co-authors were able to obtain helped to provide “direct insight into that distant time and place” from which 3I/ATLAS originates, while also providing new insights into “how unusual our own solar system may be.”

Understandably, the Webb telescope is in high demand, and Cordiner and his team had to interrupt the space observatory’s planned schedule to turn its powerful eye toward 3I/ATLAS as it made its exit.

A Deuterium-Rich Space Object

Cordiner and the research team joined astronomers from many sub-disciplines in taking the opportunity to get a look at 3I/ATLAS on its journey through the solar system, which relied primarily on Webb’s NIRSpec (Near-Infrared Spectrograph) instrument.

As previously reported by The Debrief, the telescope’s NIRSpec instrument revealed “exceptionally high” levels of deuterium—also known as “heavy hydrogen”—amounting to nearly 30 times the amount normally seen in comets within our solar system.

One thing this probably indicates is that early in its lifetime, 3I/ATLAS was likely exposed to large amounts of radiation, which gave rise to the deuterium-rich ice in its composition. However, after drifting through space for eons without coming into proximity to a star like our Sun, there were no opportunities for this “heavy water” to be converted back into the typical kind of H20 water common on our planet.

Clues from Carbon Traces

Another primary finding Cordiner and the team made is that NIRSpec data revealed only small amounts of carbon-13, as opposed to its lighter counterpart, carbon-12. Since carbon-13 enrichment is known to occur within stellar systems over time, the team interprets this as evidence for the extreme age of 3I/ATLAS, which could have origins going as far back as an astonishing 12 billion years ago.

This would place the interstellar object’s birth within the period astronomers identify as “cosmic noon,” during which our universe was undergoing its peak period in star formation. Additionally, separate observations involving the European Southern Observatory’s Very Large Telescope help to affirm the recent Webb findings, along with complementary insights into the ancient comet’s carbon content, as well as nitrogen present in the form of cyanide, revealed from recent spectrographic analysis.

“For us as scientists, finding these rare isotopes is fascinating, but the bigger picture here is looking at the possibilities of prebiotic chemistry elsewhere in the galaxy,” said Stefanie Milam, one of the recent study’s co-authors, and also a researcher at NASA Goddard, in a recent statement.

Fundamentally, what the latest data on 3I/ATLAS conveys is more than just a rare look at a cosmic voyager who briefly entered our Solar System—it is a potential glimpse at how the very building blocks of life could have made their way into our planetary neighborhood long ago, eventually arriving here on Earth.

“So far, we know of only one place in the vast cosmos where chemical ingredients led to life – our solar system, our Earth,” Milam recently said.

“Analysis of these interstellar objects is a major step towards learning how common, or uncommon, the conditions for the evolution of life are in the universe,” Milam added.

The team’s recent study, “Isotopic evidence for a cold and distant origin of 3I/ATLAS,” appeared in the journal Nature on June 22, 2026.

Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at micah@thedebrief.org. Follow him on X @MicahHanks, and at micahhanks.com.

James Webb Space Telescope (JWST) observations have revealed the colorful secret of the Pink Planet, the coldest object of its type ever directly observed.

A team of astronomers led by Northwestern University has revealed their findings in a recent paper published in The Astronomical Journal, finally describing the rose-colored haze covering the planetary-mass companion GJ504b, thanks to JWST data.

For over a decade, researchers have speculated that atmospheric salt clouds may create the pink planet’s strange hue, but this is the first concrete evidence for the hypothesis.

The Pink Planet

Since its discovery in 2013, GJ504b, commonly known as “The Pink Planet,” has been a bit of an astronomical mystery. Even the object’s description is imprecise: a “planetary-mass companion,” a nebulous category teetering between the size of a large planet and a brown dwarf, at roughly 25 times Jupiter’s mass. Residing 57 light-years from Earth, the object’s host star is similar to our Sun.

Faint due to extremely cold temperatures, astronomers cannot obtain clear enough observations with ground-based telescopes to perform spectroscopic analysis. However, from its vantage point beyond our atmosphere, the JWST’s advanced instruments have finally provided the necessary data to make sense of the object’s strange pink atmosphere.

The exoplanets most clearly observed are much hotter than our world, with temperatures between 1,000 and 2,000°F, creating a brilliance which can be seen across the gulf of space and through Earth’s atmosphere.

This giant planet is a mere 550°F, still hot by Earth standards, but far cooler than is normal for its type. According to the new study, GJ504b is an ancient world, some 2.5 to 4billion years old, with a slow cooling over time accounting for its decreased temperature.

Challenging JWST Observation

In addition to providing the first evidence for The Pink Planet’s elusive salt clouds, the team’s research has broader implications for studying cold objects, laying the groundwork for future JWST observations of such faint glows, too dim for ground-based telescopes.

“The Pink Planet is the coldest companion ever discovered using ground-based instruments,” according to Aneesh Baburaj, the study’s lead author. “Many teams all around the world performed follow-up observations to study its light, but it was too faint for ground-based instruments. That made it a perfect target for JWST. When we finally obtained its spectrum, it immediately looked interesting. But once we started digging deeper into the data, we realized it was not like anything we have analyzed before.”

To accurately analyze the light, Baburaj’s team used an advanced data-processing technique to remove considerable glare from the Pink Planet’s host star, improving the quality of the JWST data. Breaking light into separate colors through spectroscopic analysis allows scientists to determine the elemental composition of exoplanet atmospheres using JWST data.

“In the past, other astronomers observed the companion for an entire night with some of the biggest telescopes in the world to obtain a spectrum,” Baburaj said. “And they could not see the object. With JWST, our entire observation took around two hours, and we were successful.”

Analyzing the JWST Data

The team discovered water vapor, methane, carbon dioxide, ammonia, and other molecules in the object’s atmosphere, but these results conflicted with existing atmospheric models, which only made sense if the object had an extremely unlikely combination of physical features. However, once the team added clouds to the model, the effect of their salty formations on the light made the JWST data much easier to explain.

“We ran simulations with clouds, and the results aligned with what we know about cold planets,” Baburaj said. “We tried three different types of clouds, and salt clouds fit best. When we accounted for salt clouds, it subdued the signature of molecules hidden deeper in the companion’s atmosphere. Then, the results became physically possible.”

In addition to the salty clues, the researchers discovered an abundance of heavy metals. These may have something to do with The Pink Planet’s origins, as it may have originally formed as a star instead of a planet, but astronomers remain uncertain. In any case, the work process developed here will be essential to future JWST investigation of cold objects.

“This is the first time we’ve found that salt clouds are critical to explaining the spectrum of an object,” Baburaj concluded. “It’s a good reminder to account for clouds in our models.”

The paper, “JWST-TST High Contrast: First Direct Spectroscopy of GJ504b Reveals Clouds and Possible Metal Enrichment,” appeared in The Astronomical Journal on June 18, 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.

An extreme exoplanet gives astronomers a rare look at weather changing in real time.

This NASA Hubble Space Telescope image features a galaxy cluster, called CL0016+1609 or MACS J0018.5+1626, that is very bright at X-ray wavelengths and is one of the most extensively studied clusters at X-ray and radio wavelengths. The X-ray observations of this cluster revealed that it is two clusters merging along our line of sight.

Researchers requested time to observe CL0016+1609 with Hubble’s Advanced Camera for Surveys because that data would help them accurately measure the cluster’s dark-matter distribution, which helps them study the merger and the role of CL0016+1609 in the large-scale structure of the universe. Hubble can’t directly see dark matter, but its infrared and visible light observations can detect dark matter’s gravitational lensing effects on the normal matter Hubble observes.

The data in this image also includes observations with Hubble’s Wide Field Camera 3 taken as part of an observing program that obtained the first Hubble infrared images of 46 massive galaxy clusters and looked for distant galaxies gravitationally lensed by these clusters. Called RELICS (Reionization Lensing Cluster Survey), this survey found some 300 high-redshift candidate galaxies lensed by these clusters.

You can see the faint vertical arc of one of these distant galaxies in the image above. Look for it just to the left of the large elliptical galaxies in the center of the image. Another brighter, though shorter arc is visible just above and to the right of the large elliptical galaxies in the center of the image.

Media Contact:

Claire Andreoli
NASA’s Goddard Space Flight Center, Greenbelt, MD
claire.andreoli@nasa.gov

A new study of two supernova remnants, the debris left behind after stars explode, suggests the explosions came from stellar siblings that once orbited each other. The first star’s detonation sent its binary companion hurtling through space, and then, after traveling for thousands of years, the surviving star blew up too.

“Using 16 years of data from NASA’s Fermi Gamma-ray Space Telescope, our analysis uncovered gamma rays associated with a supernova remnant that was hidden in the glare of its neighbor, the Jellyfish Nebula, one of the brightest gamma-ray-emitting supernova remnants known,” said Miltiadis Michailidis, a postdoctoral fellow in the physics department at Stanford University in California. “There are so many striking connections between the two remnants that we conclude they’re likely related, giving us the first known example of a binary system where both stars have undergone supernova explosions.”

Michailidis presented the findings Wednesday at the 248th meeting of the American Astronomical Society in Pasadena, California. A paper describing the results will appear in a future edition of Nature Communications.

The study focused on a faint supernova remnant called G189.6+3.3, which is mainly visible in X-rays. It is upstaged by its brighter and better-known neighbor, the Jellyfish Nebula (IC 443). The two star wrecks, both located in the constellation Gemini, appear to partially overlap as seen in X-rays. Recent X-ray evidence suggests that hot plasma likely associated with G189.6+3.3 may extend across the entire region, a hint that the overlap may be nearly total.

A massive star explodes when its energy-producing core runs out of fuel and collapses under its own weight, triggering an explosion that blows the star apart. The explosion’s shock wave encloses a hot cloud of debris that rapidly expands into space. So far, astronomers have cataloged about 300 supernova remnants in our galaxy.  

The Fermi mission is part of NASA’s fleet of observatories monitoring the changing cosmos to help humanity better understand how the universe works. More than a decade ago, observations from Fermi’s LAT (Large Area Telescope) showed that the shock waves of supernova remnants accelerated particles to within a fraction of the speed of light, a process first proposed by physicist Enrico Fermi — the mission’s namesake — in 1949.

These high-speed particles, called cosmic rays, interact with interstellar gas to produce gamma rays, the highest-energy form of light. Protons make up 99% of cosmic ray particles. To prove that accelerated protons are responsible for the glow, astronomers search for a specific gamma-ray feature. When cosmic-ray protons smash into interstellar gas, they produce a short-lived particle called a neutral pion, which almost immediately decays into a pair of gamma rays. This emission occurs within a specific band of energies associated with the neutral pion’s mass and lies within the range detected by Fermi’s LAT instrument.

In 2013, Fermi observations proved that the Jellyfish Nebula, which is interacting with part of a glowing cloud of hydrogen gas known as Sharpless 249, produced gamma rays through this mechanism. Its neighbor, G189.6+3.3, was discovered in 1994 as part of an X-ray survey by the German-led ROSAT (Roentgen Satellite) mission.

A bright filament of gas lies between the overlapping remnants. New observations of this feature reveal that the shock wave from G189.6+3.3 slammed into dense interstellar gas there and dramatically slowed, key evidence that both remnants are interacting with the same cloud system.

Astronomers think the Jellyfish Nebula is also a candidate PeVatron, a cosmic particle accelerator capable of boosting protons to energies so high they could nearly escape our galaxy. Such particles can produce gamma rays with trillions of times more energy than visible light. Finding a second particle accelerator near the Jellyfish Nebula could offer scientists new clues for how supernova remnants develop into PeVatrons.

“The overlapping remnants, a connecting gas filament, and the availability of data from Fermi and other facilities motivated us to delve into this complex but little-studied region,” said co-author Marianne Lemoine-Goumard, an astrophysicist at the French National Centre for Scientific Research (CNRS) based at the University of Bordeaux. “With Fermi’s LAT instrument, we found gamma-ray emission associated with accelerated protons in the northern part of the fainter remnant. If both remnants are interacting with the same structure, then they must share a common distance from us.”

The team concludes the remnants lie about 6,000 light-years away, their explosion centers are separated by roughly 40 light-years projected onto the plane of the sky, and the original stars may have been 20 or more times the Sun’s mass.

Estimates of the remnants’ ages vary widely, but the team concludes that the age of the Jellyfish Nebula is 8,000 to 9,000 years, while G189.6+3.3 is between 20,000 to 110,000 years old. This means the delay between the explosions could have extended for up to 100,000 years.

In addition, the team conducted computer simulations of a million massive binary systems. They show that systems where the stars orbit close enough to exchange matter and interact during their lives can readily produce dual supernova explosions with similar separations and time delays as those found for the remnants. The team also estimated that the chance of randomly encountering this combination of observed spatial alignment and compatible distances to be less than 1%, strongly supporting a physical association.

“The evidence we’ve compiled — including observations across the spectrum, the chemical and physical properties of the remnants, simulations, and more — paints a compelling picture of a dual supernova event,” said Michailidis.

This study identifies a unique possible example of a binary system where both stars exploded as supernovae and left behind separate, detectable supernova remnants. Astronomers think that most massive stars form in binary or multiple-star systems. The Jellyfish Nebula/G189.6+3.3 complex offers astronomers a rare opportunity to study how massive binary stars evolve, exchange matter, explode, and experience velocity changes — called kicks — induced by the supernova blast. It also provides a powerful new laboratory for understanding how coupled supernova remnants behave, including how they accelerate particles, generate gamma rays, and shape their surrounding environments.

“Fermi’s gamma-ray observations of supernova remnants continue to reveal the dynamic lives of stars,” said Elizabeth Hays, the Fermi project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “We can now connect the glowing remains of two massive stars to a powerful pair that evolved together over thousands of years.”

By Francis Reddy
NASA’s Goddard Space Flight Center, Greenbelt, Md.

Media Contact:
Claire Andreoli
301-286-1940
NASA’s Goddard Space Flight Center, Greenbelt, Md.