Category: stars

New research suggests that collisions between stars in the early universe were common, which could help explain the rapid growth of supermassive black holes and the existence of strange Little Red Dots seen by the James Webb Space Telescope (JWST).

The team behind this research performed simulations of the early universe and found stellar systems were densely packed, leading to stars frequently slamming into each other. While rapid collisions would have destroyed the stars involved, slower collisions would have led to repeated mergers, creating single over-massive stars, which could collapse and form larger-than-usual black holes at the end of their lives. These could be the seeds of the first supermassive black holes.

Dense stellar environments do still exist in the modern universe at the hearts of galaxies; however, these aren't conducive to the types of collisions that would birth ultra-massive stars. That is because there are already supermassive black holes at the hearts of modern galaxies, and their immense gravitational influence speeds up orbiting stars, meaning collisions that do occur are high-speed and destructive, thus failing to birth overmassive stars.

"Perhaps the strangest outcome of our simulations is that stars can merge repeatedly within the cluster until they form one gigantic star with a mass equal to that of an entire cluster," team member Claire Williams, of the University of California, Los Angeles (UCLA), said in a statement. "When a star this huge reaches the end of its life, models suggest that it may have no option but to collapse into itself and form a massive black hole."

My, haven't you grown? How did supermassive black holes get so big so fast?

The existence of supermassive black holes before the universe was even 1 billion years old is something that has puzzled astronomers since the JWST started spotting them in 2022.

This is because black holes should need at least 1 billion years to complete the feeding and merger processes that result in a "supermassive" status of possessing millions or billions of times the mass of the sun.

One suggestion put forward by scientists to explain this is that supermassive black holes don't start out from scratch. Instead, they form from black hole seeds called intermediate-mass black holes.

Normally, when a massive star collapses, it births a stellar-mass black hole possessing a mass between 10 and 100 times the mass of the sun. This is considerably smaller than supermassive black holes that dominate the hearts of all modern galaxies with masses millions to billions of times the mass of our star.

Intermediate-mass black holes are thought to sit between these two families of cosmic titans with masses between 100 and 100,000 times that of the sun. The problem is, no single star should have enough mass to collapse and create an intermediate-mass black hole. But that is valid only for the conditions we see in the "modern" 13.8-billion-year-old universe in our immediate cosmic vicinity. Conditions were very different further out into the universe and further back in time.

Indeed, such seeds emerged from these new simulations in environments of dense star clustering, which could solve this mystery by allowing those growth processes to get a head start.

"Dense star clusters provide a natural birthplace for massive black-hole seeds in our model," Williams said. "The same environment that forms the black hole can also provide stars and gas that influence its subsequent growth."

However, this could be a two-for-one deal. The JWST has also been routinely discovering astronomical bodies called Little Red Dots in the early universe. Little Red Dots are curious because they seem to have completely disappeared by the time the cosmos reached 2 billion years old.

Little Red Dots the cosmic elephant in the room

Little Red Dots are extremely compact objects in the early universe that get their moniker from the fact that they look like red dots.

"Little Red Dots are a hot topic in astronomy. You can compare studies of people trying to understand Little Red Dots to the tale of blind people who are trying to describe an elephant by touching it, and each person describes it differently based on what part they’re touching," team member and UCLA researcher Smadar Naoz said. "Our research connects several of those perspectives together and may help us see more of the elephant."

There have been many suggestions about the true nature of these objects, but one theory suggests that they possess a rapidly growing black hole at their hearts.

The team's simulations suggest that Little Red Dots may be dense star clusters that are constantly being rocked by repeated stellar collisions. This results in a very large star, which eventually collapses to become an intermediate-mass black hole.

But if that is the case, why were there no Little Red Dots around to celebrate the 2 billionth birthday of the universe?

Less than 1 billion years after the Big Bang, the universe was devoid of well-ordered spiral galaxies, but was instead filled with dense and chaotic clusters of star birth. As these regions were rocked with frequent star collisions, the conditions were right for ultra-massive stars to form and collapse into intermediate-mass black holes.

However, as the universe cooled and expanded, these sites became the building blocks of far less chaotic galaxies. Thus, if Little Red Dots are chaotic star clusters needed to form intermediate-mass black holes, progress toward an equilibrium state could explain why they suddenly disappeared from the universe. The cosmos just wasn't extreme enough to maintain Little Red Dots anymore.

The team's research was published on Monday (Oct. 26) in the Astrophysical Journal.

Something spooky is stirring in the shadows of the infamous star Betelgeuse, a cosmic poltergeist that is disrupting the atmosphere of the red supergiant.

New radio observations have shown Betelgeuse's smaller stellar companion, Siwarha (not Betelguese Betelguese, unfortunately), cutting through the supergiant's extended atmosphere and leaving a wake in its path, like a jet boat slicing through a lake.

Because the name of this red supergiant star located about 650 light-years away from Earth, marking the shoulder of constellation Orion, is Betelgeuse, which means "the hand of al-Jawza" in Arabic, the companion was named Siwarha, meaning "her bracelet."

"This companion is orbiting so close to the star that it actually passes through its extended atmosphere," Lynn Matthews, the principal research scientist at Massachusetts Institute of Technology (MIT) Haystack Observatory who led the new observations, said in a statement.

Astronomers turn cosmic ghost hunters

Using data collected from 2021 to 2026 using the Karl G. Jansky Very Large Array in New Mexico and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, Matthews and colleagues found that Betelgeuse's atmosphere stretches into an egg shape when the companion star is farthest away and rounds out when the companion passes in front of or behind it.

The same data also showed that Betelgeuse itself has largely recovered from the "Great Dimming" that made headlines in 2020. This recovery comes after the red supergiant "sneezed" in 2020, dramatically ejecting tons of gas and dust and fading to its dimmest in more than a century.

Among the long-standing mysteries of Betelgeuse, scientists have puzzled over a brightening and dimming cycle that lasts roughly 2,100 days. Recent studies pointed to a low-mass companion orbiting deep inside the star's atmosphere, and its existence was confirmed in early 2026.

Though Siwarha itself is too faint to detect directly at radio wavelengths, its influence shows up in the star's shape, the new study found. To confirm the effect, the researchers say, they will need to observe more of the companion's orbit, especially at radio frequencies that have so far been sparsely sampled.

The Next Generation Very Large Array, a planned telescope, should make this kind of monitoring far more routine, according to the team. With sharper vision, researchers could see how red supergiants like Betelgeuse shed their material as they near the end of their lives, and how a close companion might affect that process by tugging on that ejected matter.

This research is described in a paper published in The Astronomical Journal.

"Sometimes dead is better." Who can forget the immortal words of Jud Crandall, delivered by the incomparable Fred Gwynne in the 1989 film adaptation of Stephen King's Pet Sematary? Turns out Crandall could have been talking about somewhere just as otherworldly as the cursed Chumash burial ground at the heart of one of King's most terrifying works of fiction.

That's because astronomers have discovered two husks of two zombie planets shuffling through the gory remains of what was once their planetary neighbors around a long-deceased star, or white dwarf. The shattered planets were revealed by a clear gap in the debris around the white dwarf J1328−1450, located around 1,600 light-years away from Earth. One of the remnants is estimated to be no larger than the size of the average solar system asteroid, while the other is estimated to be between the size of the moon and the dwarf planet Pluto.

If this wasn't creepy enough, this haunting planetary system could be a grisly warning about the future of our own solar system after the inevitable death of the sun.

White dwarfs like the one at the heart of this system are formed when stars around the same mass as the sun run out of hydrogen in their cores. This means they can no longer fuse hydrogen into helium, the nuclear fusion process that provides the outward push that supports a star against the inward push of its own gravity.

As a result, the stars' cores collapse while the outer layers, where nuclear fusion is still proceeding, puff out. This so-called red giant phase can see stars increase their radius by many 100s of times. When it happens to the sun in around 5 billion years, our star will expand to consume the inner planets, including Earth.

The red giant phase ends when the outer layers disperse along with the wreckage of consumed planets, leaving a smoldering stellar core, now a white dwarf, surrounded by the disk-shaped remains of its outer layers and cannibalized planetary children. But this may not be the final death of all the planets that once orbited the now-dead star.

"We have known for some time that planets may survive beyond the transformation of their central star, but this is the first example of a complex system with a double debris disc and potentially two surviving planetesimals," research leader Nicola Gentille Fusillo, an astronomer at the Università degli Studi di Trieste, Italy, said in a statement.

Violent stellar death can't kill these two planetary Jason Voorhees

This system differs from others seen because of the large gap between the remarkably stable inner and outer rings. All previously known debris discs around white dwarfs have been surrounded by single, flat, rotating disks, not a double structure like this.

"The system is a rare glimpse of the violent, chaotic process by which a planetary system meets its end, and it hints that dead stars can have disc structures far more complex than previously realized," team member Gentle Fusillo of the Astronomical Observatory of Trieste said.

The team thinks that this unique double structure is evidence of planets that weren't completely vaporized during this white dwarf's red giant phase.

That means just like the residents and campers of Crystal Lake couldn't finish off Pamela Voorhees' baby boy, even an expanding star couldn't finish these two planets.

The team's observations, made with the Very Large Telescope (VLT), revealed the presence of calcium, oxygen, magnesium, and iron in the disk around the white dwarf. This indicates the destroyed planets had a composition similar to the rocky planets of the inner solar system.

The researchers also found evidence of a diversity of composition in the destroyed planets. The chemistry of the outer rings deviated from that of the inner rings, indicating that at least two of the consumed planets had very different compositions.

"The system therefore offers a remarkable glimpse of what the future of planetary systems, including systems like our own, might look like," Lagos-Vilches explained.

The team's research was published on Monday (Oct. 26) in the journal Nature Astronomy.

Scientists are still learning about a cosmic "string of pearls," a unique celestial relic left by a supernova explosion that humanity witnessed around 850 years ago.

That is thanks to the most detailed observation of the dandelion-shaped chains of gas and supernova debris that comprise Pa 30, the only supernova remnant of its type observed in the Milky Way. What makes Pa 30 even more unique is that it has a rare "zombie star" at its heart.

Supernovas like the one that created Pa 30 are called Type Ia supernovas; they happen when a dead star called a white dwarf overfeeds on a companion star like a cosmic vampire. This overfeeding triggers a runaway nuclear explosion that usually destroys the white dwarf. But on rare occasions, the supernova doesn't completely destroy the star, and a shattered stellar body remains, called a zombie star. These events are called Type Iax supernovas.

Pa 30 was first identified in 2013 by a citizen scientist in 2013, but scientists soon linked it to a cosmic explosion recorded independently in the year 1181 in Japanese, Chinese, and Arabic historical documentation. That makes this one of only five supernovas seen before the invention of the telescope.

"Reliable historical records of stellar explosions extend back only about a thousand years. For all we know, there might well be similar remnants still lurking in the dark in our own galaxy," team member Ilaria Caiazzo, assistant professor at the Institute of Science and Technology Austria (ISTA), said in a statement.

"Today, we are lucky to study an intriguing object we know was observed by astronomers who made three independent historical records of the event centuries before the invention of the telescope."

Solar system-sized pearls

Pa 30 is a good laboratory to study supernovas because, at around 7,500 light-years away, it is relatively close to Earth on cosmic scales. For instance, the heart of our galaxy is around 26,000 light-years away. "We can see this much detail because of Pa 30's proximity to Earth," said Caiazzo. "This proximity makes Pa 30 uniquely valuable for study."

It is also an important subject of study because it is the only supernova remnant in which we can see a zombie star.

Using the Gemini North telescope, Caiazzo and colleagues zoomed in on Pa 30, discovering knots along the strands of gas radiating out from the site of the cosmic explosion, like pearls on a string.

These pearls are each wide enough to encompass the orbit of Neptune, the most distant planet from the sun, ten times over.

"The planetary region of our solar system could fit in each knot about ten times with room to spare," said Caiazzo. "The knots are quite strikingly uniform. We are excited to try to model them."

The team also discovered that the zombie star sits almost perfectly at the heart of Pa 30. When these cosmic explosions happen, they should provide any debris, including zombie stars, with a kick. The fact that this "living dead" star still sits dead center of this wreckage suggests that when this explosion happened, it was roughly symmetrical and the kick was relatively light.

"Explosions conserve momentum. If the explosion itself was perfectly symmetric, the ejecta should also be symmetric, and the surviving star should not receive a substantial kick," Caiazzo said. "We were able to measure a precise upper limit of the remnant star's transverse kick speed, showing that it was surprisingly small. We practically don't see the star moving away at all."

While there are still many mysteries surrounding Pa 30 and its zombie occupant, one of the most exciting prospects emerging from this research is the possibility it will help identify the wreckage of other Type Iax supernovas in our galaxy.

"While we can see Type Iax supernovas in distant galaxies as point sources of light, resolving the remnants of such explosions is only possible in our own galaxy and in very few nearby ones," Caiazzo concluded. "Eventually, we plan to use Pa 30's distinctive properties to search the Milky Way and nearby galaxies for similar objects."

The team's research was published in The Astrophysical Journal.

Using NASA’s SPHEREx spacecraft, astronomers have studied a host of "failed stars," also known as brown dwarfs.

These strange cosmic bodies straddle the line between planets and stars, possessing a mass between 13 and 80 times that of Jupiter (0.013 to 0.08 times the mass of the sun). They get the nickname failed stars because they form like stars from collapsing clouds of gas and dust but fail to gather enough mass to trigger the fusion of hydrogen to helium in their cores, the process that powers actual stars.

This formation process also means that brown dwarfs are cosmic loners, wandering the darkness of space alone, bereft of the light of a parent star. That description might sound like lyrics from a Type O Negative song ("Black No. 1," anybody?). And that's apt, according to the leader of the new study, which reveals that, chemically speaking, the atmospheres of these dark and cloudy worlds are not unlike those of our solar system's gas giant planets.

"They’re kind of goth," Zafar Rustamkulov, of the California Institute of Technology (Caltech), said in a statement. "Unlike exoplanets, free-floating brown dwarfs are completely independent celestial objects that will fade into eternity alone. We’re still learning how complex they are."

Rustamkulov added that, from Earth orbit, SPHEREx — short for Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer — sees wavelengths of light that are nigh-impossible to see with telescopes on the ground because water in Earth’s atmosphere absorbs them. That is important for bringing brown dwarfs into the light.

"We are picking up light from the deep, red clouds of brown dwarfs all over the sky," he said.

A forest (of brown dwarfs)

Brown dwarfs have been somewhat mysterious since their discovery in the 1990s, due to the fact that the small amount of nuclear fusion that occurs within them causes them to emit no more than a faint glow. That means that our understanding of their makeup, their storms, and their evolution really only comes from theory.

To help lift this observational darkness, the team turned to data from SPHEREx. They studied 37 nearby brown dwarfs in a spectrum of light including 102 wavelengths, from the deepest red our eyes can see to the invisible infrared light. These local failed stars spanned the full temperature range for brown dwarfs — from 4,000 degrees Fahrenheit to minus 10 degrees Fahrenheit (2,200 to minus 20 degrees Celsius).

Considering that the temperature of the sun is about 10,000 degrees Fahrenheit (5,500 degrees Celsius), you could definitely say brown dwarfs run cold.

The spectra of brown dwarfs seen by SPHEREx allowed the team to determine that their atmospheres are chemically rich in water, carbon dioxide, carbon monoxide and methane.

"We’re seeing the signatures of these molecules and how they change from object to object across the entire temperature regime," said team member J. Davy Kirkpatrick, also of Caltech. "Our paper concentrated on just three dozen, but we have thousands more that we are in the process of analyzing.

"I really want to see what bounds the universe places on the variety of brown dwarfs."

All my colors

Brown dwarfs have been routinely observed by other telescopes, including NASA's James Webb Space Telescope and the agency's now-retired Spitzer Space Telescope, but the wide wavelength coverage of SPHEREx has made it particularly useful in observing these failed stars. That's good news for astronomers waiting for change in the atmospheres of brown dwarfs as they age and grow cold.

The researchers found that some brown dwarfs observed by SPHEREx are at a stage of extreme change in which their clouds are clearing, creating atmospheres rich in methane.

The team may have discovered significant new details about brown dwarfs, but they are still on the proverbial mystery street when it comes to these strange celestial objects,

"The state-of-the-art models are capturing the general chemical trend, but when it comes to these cloudy transitions, the models are struggling to match the data," said Rustamkulov. "No two brown dwarfs are alike. Even at the same temperature, their spectra look quite distinct."

"This journey has turned many of us into accidental meteorologists. We know how hard it is to predict weather on our own planet, and we realize it's going to be just as challenging to explain the phenomena we see in these bizarre, cold objects," Kirkpatrick said. "The findings are a call to action to explore even more of these dark worlds."

As astronomers resond to that call to action, I will ponder how I could have worked Bauhaus' Goth classic "Bela Lugosi is Dead" into this article.

The team's research was published on Sept. 28 in The Astrophysical Journal.

How awesome would it be if the sun could take on a spooky green glow for Halloween? It turns out that scientists have discovered that our star may indeed go green, but only billions of years from now after its death  — and only if it then starts eating planets like a cosmic zombie.

That's possible because scientists have discovered that white dwarfs, the type of stellar remnants sun-sized stars leave behind when they die, can actually take on a range of colors including green if they snack on their rocky planets like cosmic cannibals.

For stellar scientists, the colors of stars have always been indicative of their temperatures. Cool stars look orange, while stars like the sun look white, and the hottest stars glow pale blue. This is akin to a blacksmith's iron glowing red, then orange, then white-hot as it heats up. Researchers have always assumed that white dwarfs follow the same rule. However, new research suggests that these stellar corpses could glow in a range of colors including green, pink, cyan, yellow, and purple. That means the universe is far more colorful than we suspected.

"Most stars, including most white dwarfs, behave like 'perfect radiators,' so their color is set almost entirely by temperature. But nobody had really looked into what else might be possible for white dwarfs," team leader Mark Hollands of the University of Warwick said in a statement sent to Space.com.

"It turns out these incredibly dense stars caaaaan produce colors nobody expected, and some of them genuinely surprised me."

How white dwarfs break stellar color rules

White dwarfs get their name because when they were discovered, they appeared surprisingly hot and glowed white or pale blue. However, this new research suggests that this slightly bland and uniform appearance is because no white dwarf is close enough for Earthbound astronomers to see their true colors.

The key to the rainbow-like array of colors this team suggests white dwarfs could possess is their density. White dwarfs form when stars with a mass roughly that of the sun run out of fuel and can no longer support themselves against their own gravity, causing their cores to collapse. As a result, the matter that makes up white dwarfs is around the density of water, millions of times denser than the sun's surface, the photosphere.

In these conditions, elements like carbon, calcium, and sodium can interact with the surrounding dense helium plasma and absorb light across a wider range of colors than they would at lower densities. That shifts the colors of white dwarfs away from the white/light blue seen for a perfect radiator of heat.

The researchers found that the colors of white dwarfs would fit into distinct groups tied to the individual chemical makeup of the stellar remnant's atmosphere.

White dwarfs abundant in carbon should be pink or purple, while those that have been enriched with debris from consumed asteroids and comets, and the remains of old planetary systems, would take a more yellow hue. Cooler white dwarfs with mixed hydrogen and helium atmospheres often would glow cyan or pale blue, caused as hydrogen molecules collide with helium atoms in their dense atmospheres.

One of the most striking examples of white dwarf coloration, however, would arise when one of these living dead stars starts feeding on the planets around it like a horror movie zombie.

Zombie white dwarfs go green

The researchers found that some dead star white dwarfs can go a little green around the gills after snacking on orbiting planets.

An example of this is WD J1330+6435, a cool white dwarf located around 326 light-years away, which has been accreting rocky material from a planetary companion. This has enriched its atmosphere with calcium, lithium, and sodium, and the team's model suggests this would have led WD J1330+6435 to adopt a green hue.

But unlike the green-tinged zombies of George Romero's classic Dawn of the Dead, there are no hordes of these green-faced cosmic zombies ... yet.

The researchers think that no other star, living or dead, has ever been credibly reported as green. That makes WD J1330+6435 the first known genuinely green star.

"The traces of sodium in the atmosphere of this white dwarf absorb the orange part of the spectrum, leaving behind a ghostly green glow," Hollands said. "Imagine standing on a planet and looking up at a green star. It feels like something out of science fiction."

Scientists see red

The team didn't just discover that a known white dwarf is the first-ever green star; they also discovered what could be the reddest star ever in the form of the white dwarf WD J1011+2845.

Located just 48 light-years from Earth, this white dwarf has a deep convection zone that carries carbon from its core to its surface. These carbon molecules distort light from the white dwarf, causing a deep salmon-pink glow unlike anything seen in any other star.

Despite this rainbow of white dwarfs, the team theorizes that white is still the most common color for these stellar corpses. Only five of the 151 white dwarfs within around 65 light-years of Earth have extraordinary coloring. Extrapolating this to the total population of white dwarfs, the team estimates that only one in 30 of these dead stars has an unusual color.

"One in thirty might not sound like a huge fraction, but across the entire population of white dwarfs in the universe, that is still a lot of oddly colored stars out there," Boris Gänsicke, Department of Physics, University of Warwick, said. "Yet if we take the median across a representative population of white dwarfs, we found that the average white dwarf really is white."

The team's research was published on Thursday (Oct. 14) in the journal RAS Techniques and Instruments.

A new image from the European Space Agency's Mars Express spacecraft reveals the powerful erosive forces that have shaped and re-shaped the surface of the Red Planet over long periods of geological time.

What is it?

This new Mars Express image captures Amazonis Mensa, a large, flat mountain on the Red Planet that offers planetary scientists a glimpse into the many factors that can sculpt a world's surface.

In this photograph, several features stand out to help illustrate this. Easiest to make out are the large round craters created by ancient impacts on the surface of Mars. However, many of these craters have been at least partially filled by lava flowing across the surface of the Red Planet around three billion years ago, according a statement from the European Space Agency (ESA) accompanying the image.

More interestingly, rippled structures known as yardangs can be seen to the left and right sides of the image. These ridges "form as loose sand particles are whipped up by wind and deployed a little like a cosmic sandblaster," according to ESA.

In the image, the two groups of yardangs ripple across the Martian surface in two different directions. This is because Amazonis Mensa acts as a windbreak, pushing material blown by winds in separate orientations.

Why is it incredible?

For over 20 years, Mars Express has been providing scientists with an unparalleled look at the Martian surface, helping us better understand the forces that have shaped the Red Planet over eons.

Now you see them, now you don't. Scientists have discovered that some of the universe's most powerful explosions, hypernovas, may not happen at all.

These explosions, known as hypernovas, were first proposed to explain unusual stars in the halo of our galaxy, the Milky Way, and in a neighboring dwarf galaxy. It was suggested that these stars could only form from the debris of an explosion 10 times more powerful than the 'average' supernovas.

The team behind these new findings suggests that ordinary supernovas could actually account for these stars when the uneven or non-spherical way they fling out matter is considered.

"If we look at a supernova today, the star's materials are not spread evenly. Oxygen might predominantly fly in one direction, sulphur in another. New stars might form from a mix of pieces of the supernova, not its overall mix of elements," team leader Anmol Aggarwal of University College London (UCL) said in a statement. "We developed mathematical models that took account of this and found in all cases that stars with a very unusual mix of ingredients were most likely formed from ordinary supernovas.

"All the evidence we see for hypernovae is suddenly gone."

Hypernova vs. supernova: What's the difference?

Supernovas occur when massive stars run out of fuel for nuclear fusion, effectively ending their lives. This results in the star's core collapsing, sending shockwaves rippling through its outer layers, causing explosions we call supernovas.

Hypernovas are proposed to occur in a similar way, but for an even more massive and rapidly spinning star. This results in a vastly more energetic explosion.

When supernovas or hypernovas happen, they fling elements that the dying star has forged throughout its lifetime into their surrounding cosmic environments. These elements eventually become the building blocks of the next generation of stars.

That means analyzing the chemical signatures of stars can tell stellar scientists about their family histories.

"Just before a star goes supernova, it has layers like an onion, with heavier elements at the center and lighter ones further out. Our model looks at how much material from each layer or each region would be needed to fit the observed star," Ralph Schoenrich of Mullard Space Science Laboratory at UCL said. "We still don’t know how well the supernova material gets mixed before it forms new stars. That is despite decades of work in this area. Our research suggests some mixing goes on, but incomplete mixing.

"We need to take this into account in our models of how chemicals evolve in galaxies and of how the interstellar medium works."

The team began their investigation by observing four stars that are suspected to have been forged from material ejected in a hypernova explosion. Three of those stars were more likely to have been created after supernovas, the team concluded.

The scientists then studied a single red giant star in the halo of the Milky Way with an odd chemical composition, including an overabundance of heavy elements like silver and uranium. These are too heavy to be forged in the cores of all but the most massive stars, the kind of stars that go hypernova.

Such elements could also be created when two massive and dense stellar remnants called neutron stars collide and merge. However, this star doesn't have certain other heavy elements that would be present after a neutron star collision.

This team considered the origins of this star using a model of the Milky Way that has been rapidly enriched with elements heavier than hydrogen and helium, which astronomers call metals, via the death of the first generation of stars.

The rapid speed at which the star spins and the fact it exists at the outskirts of the Milky Way led the team to conclude that this star escaped a metal-poor dwarf galaxy and was eventually dragged into our galaxy. The event that created it, they concluded, was the combination of a neutron star merger and an ordinary supernova.

No hypernova required. An asymmetrical supernova would be enough, the scientists found.

The team's research was published as two papers in the journal Monthly Notices of the Royal Astronomical Society.

Astronomers investigating mysterious flashes of X-rays believe that these blasts could stem from collisions between neutron stars, the events that forge elements like gold, silver, and platinum.

The event designated EP250704a, was first seen on July 4, 2025, as a blast of gamma rays lasting half a second followed by a bright X-ray emission lasting 10 minutes. After receiving an alert from the joint European-Chinese Einstein probe that witnessed the blast, a team of astronomers started to hunt for its cause by studying the aftermath of the explosion using the European Southern Observatory's Very Large Telescope (VLT), the Very Large Array (VLA), and other telescopes.

According to astronomer Niccolò Passaleva who led the observations of the X-ray flash with the VLT, this cosmic outburst was unlike any scientists had seen before. "This is the longest-lasting prompt X-ray flash ever observed from a neutron star merger," Passaleva said in a statement. "It is an opportunity to have a front-row seat to the most extreme forces of the universe and discover more of its secrets."

Neutron stars are created when massive stars die in supernova explosions, cramming one or two the mass of the sun into a width akin to a city on Earth and creating material so dense that a single teaspoon of neutron star matter brought to Earth would weigh 10 million tons. When these extreme dead stars slam together, they create environments so turbulent and violent they are capable of forging elements so heavy that even the hearts of stars can't do it. Elements like the gold on your finger.

These collision and merger events, marked by flashes of light called kilonovas, have long been associated with flashes of high-energy gamma-rays that disappear within two seconds, but new research suggests some neutron star mergers could reveal themselves via blasts of X-rays lasting minutes.

In particular, scientists have wondered if neutron star mergers could be the cause of hundreds of X-ray flashes in distant galaxies discovered by the Einstein probe since its launch in 2024. While some of these have been linked to the supernova-explosive death of massive stars that can create a neutron star or a black hole, others have defied explanation. EP250704a is one such X-ray flash.

"When I saw the X-ray data from this new event, I realized something was up," team member Eleonora Troja, part of the Einstein Probe European collaboration, said in the statement.

The team believes that there is something special in the neutron star merger mix that results in these X-ray bursts.

Merging with a magnetar

All neutron stars are created the same way from the collapsing core of a massive star, but not all neutron stars are equal.

Just as an ice skater pulls in their arms to increase the speed of a spin, the rapid reduction in radius of a collapsing stellar core can "spin up" the rotation of a neutron star to 'over 700 times per second. This collapse can have another consequence too.

It turns out that magnetic fields get stronger when magnetic field lines are pushed closer together. That means the collapse of a stellar core with an already powerful magnetic field can create a neutron star with the strongest magnetic field in the universe. Those neutron stars have a special name: magnetars.

The team behind this research thinks that the neutron star merger in question involved at least one magnetar.

"If the remnant of the collision is a magnetar, it could keep bursting for longer," Troja said. "Magnetars are rapidly spinning neutron stars with huge magnetic fields. When they dump their magnetic power into the surroundings, they can make any explosion brighter and longer-lasting."

The researchers ruled out a supernova as the cause of the X-ray burst and were also able to determine that the light from this collision has been travelling to Earth for 6 billion years.

Discovering more of these extreme X-ray flashes could help astronomers determine how often magnetars are formed through these neutron star mergers, Passaleva said in the statement.

The team's research was published in the journal Science Bulletin.

Astronomers have observed a "vampire" star feeding on a brown dwarf companion for the first time. It is a slow and gruesome death that could last for billions of years, despite the fact that the star is snacking on the equivalent of 5.2 trillion quarter-pounder burgers every second.

Brown dwarfs straddle the line between planets and stars, with masses from 13 to 80 times that of Jupiter or 0.013 to 0.08 times that of the sun. They get their unfortunate nickname "failed stars" because, though they form from a collapsing cloud of dense gas, they fail to gather enough mass to trigger the nuclear fusion of hydrogen to helium in their cores, the process that defines what a star is.

This newly discovered brown dwarf, found to be a snack for a small companion star, is located in the system ZTF J0440+2325, which dwells around 300 light-years from Earth. This represents the first time astronomers have seen a low-mass star acting as a stellar vampire, stealing material from a low-mass stellar companion. The slow rate at which this is occurring indicates this cosmic vampirism will last for hundreds of thousands to billions of years.

"When we think of stars interacting with planets or brown dwarfs, the picture is always that the star eventually swallows the other thing," team member Kevin Burdge of the Massachusetts Institute of Technology (MIT) said in a statement. "This is what will happen to the Earth when the sun becomes a red giant. But here, we've found an alternative: Instead of swallowing the thing up, the star can gradually eat it for billions of years."

A strange cosmic triangle

This new system was first observed in observations of the sky conducted by the Zwicky Transient Facility (ZTF) in the form of a strange light triangle that repeatedly appeared in the data.

"I remember first looking at this and thinking: Stars don't make triangular waveforms like this," Burdge explained.

At the time, Burdge and colleagues were hunting for so-called "black widow pulsars" that contain a stellar remnant called a neutron star feasting on a companion star much like how the arachnid of the same name devours its prey. However, because these systems contain a low-mass object gravitationally tugging on a high-mass companion, there is usually a "wobble" in their light signature, and the team found no "wobble" in this particular light signature.

"We weren't seeing that whipping back and forth here," said Burdge. "It didn't make any sense. We couldn't explain what this was."

Ruling out a black widow pulsar as the origin of this strange repeating light signal in ZTF data, Burdge and colleagues followed another hunch; proposing that this is a more balanced system with objects of similar masses.

"If you have less mass in the system overall, things can gently orbit each other without whipping back and forth," Burdge said. "That was the idea. But we never had any proof. And this weird triangle just sat for years."

That was until Burdge and colleagues revisited it, determining it originated from within the boundary of the Milky Way. Designating the source ZTF J0440+2325, the team followed up with multiple telescopes. With further observations, they found a slight wobble, less than seen for black widow pulsars but not insignificant.

"That was the real clincher for this system," team member Aaron Householder of MIT said. "When we measured that wobble, we found we were not seeing a black widow. This was a low-mass star that’s orbited by a brown dwarf. The wobble was too small in amplitude to be anything else."

What else do we know about ZTF J0440+2325

The researchers were able to figure out that the brown dwarf takes around 87 minutes to orbit the star feeding upon it. That means that this entire system could fit within the sun.

The team was also able to determine the mass of both bodies in ZTF J0440+2325. The star has a mass around 85 times the mass of Jupiter, with the brown dwarf has a mass around 25 times the mass of the gas giant.

Though the star is stripping and accreting matter like black holes sometimes do with stars, the huge difference in size between the star in ZTF J0440+2325 and a typical black hole means this proceeds differently. That is because, despite having many times more mass than the sun, black holes are smaller than the sun with radii ranging from 6 miles to 190 miles (9 kilometers to 300 kilometers).

When a black hole strips matter from a star, this stolen material forms an accretion disk around the black hole that then gradually feeds it. In the case of this system, the stolen brown dwarf matter is falling directly to the star.

"The difference here is: The thing absorbing matter is not a tiny black hole but a star, which is relatively big in size," Burdge said. "So matter just pummels directly onto the surface, at very high speeds, like an asteroid hitting the moon."

The team estimated the rate at which matter falls from the brown dwarf to the star, finding it to be the equivalent of 1/100,000 of Earth's mass per year. That's about 5.2 billion quarter-pounder burgers every second, or maybe 1.2 trillion 1-pound burritos if burgers aren't your speed.

That seems like a lot, but it is just a tiny fraction of the brown dwarf's total mass, making this a slow and steady transfer of material that could go on for billions of years.

This neatly loops back to the initial puzzle that began the investigation into this system in the first place: that weird triangle light signature. Viewed from a distance, the steady feeding process would proceed like a triangle as the victim brown dwarf orbits the star that is eating it.

"It's like you've got this continuous fireball on one of the objects, and as one orbits the other, that hotspot comes in and out of view, and the peak of the triangle signal is when you’re looking right at the fireball," Burdge said.

The team now intends to hunt for more similar systems within the Milky Way.

"It's inspiring a lot of new searches on our part,” Householder concluded. "I think we're going to learn a lot about a different kind of way that planets and brown dwarfs interact with their host stars."

The team's findings were published on Monday (Oct. 5) in the journal Nature Astronomy.