Category: stars

When stars the size of our sun die, they leave behind powerful stellar remnants called white dwarfs — and these white dwarfs can transform into even more extreme objects called neutron stars, composed of the densest material in the universe. However, scientists have found that conditions must be "just right" for the major makeover to occur. You can think of it like a cosmic "Goldilocks" situation.

As it turns out, the white dwarf has to be feeding on a companion star like some kind of cosmic vampire.

Neutron stars and white dwarfs are both born when stars run out of the fuel supplies needed for nuclear fusion happening in their cores, but the difference between the two lies with their masses.

Stars with masses similar to that of the sun end their lives when they run out of hydrogen in their cores. This halts the nuclear fusion process — which involves converting that hydrogen to helium — leading to the stars collapsing and shedding their outer layers to become a white dwarf with around the mass of the sun crammed into the width of Earth.

When stars with masses around eight times that of the sun collapse after running out of hydrogen in their cores, they generate enough pressure and heat in these cores to fuse the produced helium into even heavier elements. This process only ends when the star attains a core of iron. The final collapse results in a supernova explosion and creates a neutron star with a mass between one and two times that of the sun. That's the usual way neutron stars form.

However, what if there's a bridge between the white dwarf scenario and neutron star scenario? Scientists have long suspected there is indeed a pathway for a white dwarf to become a neutron star. This new work maps out that pathway, calling it accretion-induced collapse (AIC).

"In AIC, the progenitor is already a stellar remnant, and the trigger is not its own evolution but material handed to it by a companion," team leader Laurenz Thümmler of ETH Zurich told Space.com.

The researcher added that an AIC begins with a stellar remnant in the form of a white dwarf, while the traditional route to birthing a neutron star begins with a massive "living" star. Yet, in the AIC, the collapse of an overfeeding white dwarf continues in a broadly similar way to the collapse of a massive star that creates a neutron star.

As Thümmler explains, in both cases, the neutron star creation process involves the massive star's core imploding and zippy particles called "neutrinos" carrying away energy from the event. However, an important difference is in the "standard" massive star collapse scenario, the subsequent core-collapse supernova and neutron star birth happens inside a thick envelope of material that has been ejected during the massive star's death throes. In AICs, however, this thick envelope of matter is absent.

"AIC is expected to be faint and fast, and why so little matter is ejected compared with an ordinary supernova. Not all white dwarfs could undergo an AIC, and that is the essential point."

Though AICs have been theorized about for years, Thümmler and team wanted to know what characteristics a white dwarf would need in order to undergo this transformation. They set about investigating this using 3-dimesional simulations.

It's what is inside that counts

Most white dwarfs consist of carbon and oxygen. However, some stars collapse to form a white dwarf composed of oxygen, neon and magnesium. That only happens for a narrow range of stellar masses, meaning this composition represents a minority population of white dwarfs.

When carbon and oxygen white dwarfs overfeed on stellar material from a companion or donor star, they eventually reach the so-called Chandrasekhar limit, usually around 1.4 stellar masses. Above this limit, they can go supernova. They don't become neutron stars as a result of these "Type 1a" supernovas, however, but are rather completely destroyed. Oxygen, neon and magnesium white dwarfs can avoid that destruction thanks to their high densities.

"They are typically born more massive and denser than carbon-oxygen white dwarfs and therefore require less additional mass to approach the Chandrasekhar limit," Thümmler said.

However, Thümmler and colleagues discovered this isn't the only condition needed to provoke an AIC. The white dwarf can't be too greedy either.

The team found that the accretion rate, or rate at which material from the donor star falls onto the white dwarf, has to fall within a fairly narrow window to allow an AIC to occur.

"If it is too low, nova eruptions can expel much of the accumulated material again; if it is too high, winds, envelope expansion, or binary interaction can prevent the white dwarf from reaching the conditions required for collapse," Thümmler said. "The accretion has to be fast enough, and steady enough, to get it there without triggering explosive burning along the way.

"When those conditions hold, electrons are captured onto neon and magnesium nuclei. This removes the pressure supporting the star, and the collapse follows."

All this means that AICs are expected to be rare events, although the rate at which they occur remains highly uncertain.

The team also found the environment around AICs is somewhat surprising.

"We expected the most neutron-rich material, which produces the heaviest elements, to emerge along the rotation axis, since that is where the magnetically driven outflow is strongest," Thümmler said. "It does not."

Instead, the team's models revealed neutron-rich material emerging at the mid-latitudes of white dwarfs as they transform into neutron stars. This is region where the outflows of matter driven by intense magnetic fields collide with winds heated by energy-carrying neutrinos.

Thümmler explained that this is significant because it means that these events would appear different based upon the angle at which they are observed.

How to spot white dwarf transformations

Laurenz said these AICs could be identified by Vera C. Rubin Observatory and other telescopes as a bright ultraviolet and optical event lasting two to three days, potentially accompanied by X-ray emissions and longer-lasting radio emissions.

However, the neutron stars created by such events may be difficult to distinguish from stellar remnants birthed in the traditional way.

"They are expected to populate the lower end of the neutron-star mass distribution because the collapsing white dwarf has a mass close to the Chandrasekhar limit and ejects relatively little material," Thümmler said. "However, ordinary stellar-collapse channels, particularly those involving low-mass progenitors, can also produce neutron stars with masses of approximately 1.1 to 1.4 solar masses, so a low mass alone would not uniquely indicate an AIC origin."

The team isn't done investigating AICs, with Thümmler explaining there are two main approaches to take next.

"The first is to make the predicted light curves more reliable by following both the radioactive heating and energy injection in substantially greater detail," Thümmler said. "This requires distinguishing energy carried by gamma rays, which can escape relatively early from the low-mass ejecta, from that deposited more efficiently by charged particles, while also modelling how the neutron star wind heats and accelerates the heavy-element-rich material."

The team's simulations can then be used to follow the expansion of the ejecta from the AIC and calculate how the observed light curve and spectra depend on viewing angle.

"This work is currently underway," Thümmler said. "The second direction is to test the robustness of the explosion geometry, since our present models begin with a relatively simple magnetic-field configuration and more complex or tilted fields may produce different angular ejecta patterns."

The team's research is available to view as a pre-print on the paper repository site arXiv.

Using the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope, astronomers have watched as two stars come together to form a massive stellar binary. The observations revealed that these stars didn't form from the same collapsing cloud of gas and dust, as most binary stars are assumed to form, but instead came together later in their infancy.

Here on Earth, we are slightly prejudiced by our single sun to view stars as somewhat solitary bodies. However, around half of sun-sized stars in the Milky Way have a companion star. This percentage of stellar partnership rises to around 90% of massive stars. Eventually, these massive stars go supernova and shape their cosmic surroundings. Thus, understanding these binary systems is vital to our understanding of stars and of galaxies in general.

The team behind this research initially observed the still-growing massive stars, or protostars, in the binary system IRAS 07299−1651, located around 5,300 light-years away in 2019. At first, the researchers didn't see anything that suggested these stars didn't form from the same disk-shaped cloud of gas and dust that later fragmented. However, one thing really stood out: the disks of material surrounding and feeding these protostars are oddly misaligned.

Over the course of eight years, the team mapped subtle shifts in the position of the stars using ALMA in addition to the Very Large Array (VLA), as well as infrared images from the James Webb Space Telescope (JWST) and the Very Large Telescope (VLT).

"For the first time, we were able to watch two massive stars move around one another while they were still being born," team leader Yichen Zhang of Shanghai Jiao Tong University, China, said in a statement.

The team was able to reconstruct the full 3-dimensional structure of IRAS 07299−1651 for the first time, obtaining details about how the stars orbit each other, the way their disks are aligned, and the angle at which they blast jets into space.

"Each telescope revealed a different piece of the puzzle," team member Rubén Fedriani, of the Instituto de Astrofísica de Andalucía (IAA) in Granada, Spain, said. "The combination of radio and infrared observations provides the most exquisite detail on the formation of this massive protobinary system."

Unexpected chaos

The team's observations took them by surprise. They were expecting these stars to orbit each other in neat, near-circular orbits. Instead, the orbits were found to be highly flattened or "eccentric," almost parabolic.

If the stars had formed from the same disk of material, then even after it fragmented, the individual disks surrounding the stars would be aligned. However, that wasn't the case; the disks are tilted at a sharp angle to each other and to the orbits of the stars.

"It felt like solving a three-dimensional puzzle," team member Yao Wang of Shanghai Jiao Tong University said. "Each new observation added another piece, and eventually the orbit, disks, and jets all came together into a single, coherent picture."

The chaotic structure of IRAS 07299−1651, as observed by the team, is difficult to explain if the two stars emerged from the same disk of material.

Instead, the researchers theorize that the two stars were born in individual clouds of gas and dust, before a chance encounter brought the two infant stars and their respective natal cocoons together.

Tracing back the orbits of the stars, the researchers found that this encounter likely occurred around 60 years ago. Considering stars live for billions of years, that is an instant on a cosmic timescale. The disk-shaped pockets of material around the stars have thus far survived the encounter, retaining their well-defined structures.

"This study demonstrates that the early lives of stars can be quite chaotic, with a chance encounter leading to this gravitational dance and stellar coupling," team member Jonathan C. Tan of the University of Technology and the University of Virginia said.

What the team can't yet establish is whether these stars are destined to stick together or if they will eventually move apart. Indeed, this fate may not have been sealed yet; interactions with the surrounding gas could determine what shape this system takes in the future.

The team hopes that further observations of IRAS 07299−1651 will help to better understand what the future holds for these stars.

In the meantime, the long-term monitoring approach adopted by the researchers could provide scientists with a powerful new way of investigating other young massive binary systems. This could reveal how common encounters like this are and if more binary systems are composed of stars brought together by chance encounters.

The team's research was published on Tuesday (Sept. 8) in the journal Nature Astronomy.

Scientists are closer than ever before to understanding how stars forge the elements that comprise our planet, bodies and pretty much everything else around us — and they're gaining a clearer picture of where star explosions fit into the story.

New research reported in two different papers looks at how stars forge elements as they explode and how these supernova explosions spread those elements — and other elements stars have forged during their lifetimes — throughout the cosmos.

Astronomers have been studying the bright supernova deaths of massive stars for centuries, but they still don't quite understand how these explosions proceed.

The first paper looked at one way to investigate supernovas. It uses a radioactive element produced by these explosions called titanium-44, which lingers long after supernovas fade. Researchers have now collected experimental evidence that determines how much titanium-44 is created in a supernova, finding that these cosmic explosions produce 35% more of this element than expected.

With this knowledge in hand, scientists can now develop robust computer models of supernovas and compare these models with astronomical observations. This could bring them much closer to understanding how these explosions progress.

"It's exciting to see just how far the field has come," Christopher Cousins, a postdoctoral researcher in the University of Surrey's Nuclear Physics Group, said in a statement. "A measurement like this would have been considered out of reach only a couple of decades ago, but it now gives us new insight into one of the biggest unanswered questions in astrophysics."

The second paper honed in on a particular brand of stellar explosion called a Type I supernova. These occur when a dense stellar remnant called a neutron star drags material from a companion stellar body. The intense gravitational influence of the neutron star — a stellar corpse that has one to two times the mass of the sun crammed into a body about 12 miles (20 kilometers) wide — means that, when this stolen stellar matter hits their surfaces, a thermonuclear explosion is triggered.

These blasts forge heavy elements and release incredible amounts of energy, some in the form of X-ray bursts.

The authors of this paper, hailing from the Facility for Rare Isotope Beams (FRIB) in Michigan, studied the nuclear reaction that triggers X-ray bursts in greater detail than has been possible before.

This revealed the long-debated role of the so-called nickel-copper cycle, the temporary trapping of nuclear material during supernovas. Scientists previously didn't know if material was trapped in the nickel-copper cycle during X-ray bursts.

This research reveals that this does happen, but only in small proportions. It gives scientists a clearer picture of how Type I supernovas proceed.

"Despite decades of research, we still don't fully understand the nuclear reactions that power some of the universe's most spectacular stellar explosions," said Gavin Lotay of the University of Surrey.

"These two studies give us a much clearer picture of how these explosions happen, allowing us to compare our models more closely with astronomical observations and bringing us closer to understanding how the chemical elements are created and spread throughout the universe," he added.

The two papers were published in the July edition of the journal Physical Review Letters.

Betelgeuse may be a well-known and often-studied stellar object, but that doesn't mean astronomers aren't capable of capturing this doomed star in a completely new light.

A team of scientists examined the doomed red supergiant star with the Atacama Large Millimeter/submillimeter Array (ALMA), gaining new, highly detailed insights into its turbulent surface.

Betelgeuse, located around 600 light-years away, captured the public's attention a few years ago when the rapid and dramatic dimming of the infamous highly evolved star led some scientists to hypothesize that it was about to explode in a spectacular supernova. That hasn't happened, and scientists are now less convinced that this explosion is immediately imminent, but Betelgeuse remains the subject of intense scientific scrutiny.

"Its eventual fate as a supernova makes it fascinating to know what it actually looks like now," team leader Bill Dent, an astronomer at the European Southern Observatory (ESO), said in a statement.

The newly released ALMA images of Betelgeuse, captured in 2023, show bright hotspots on the star's surface and an almost corrugated texture arising from vast amounts of plasma shifting through the star, which has around 20 times the mass of our sun, but is puffed out to around 800 times the size of our star.

The observations show the red supergiant has an atmosphere with a temperature of around 3,680 degrees Fahrenheit (2,030 degrees Celsius), but possesses at least two regions even hotter than this. One of these areas is 980 degrees Fahrenheit (530 degrees Celsius) hotter than the plasma surrounding it.

The uneven nature seen by ALMA is likely the result of massive convective movements in the star, hot plasma rising through the star and generating shockwaves that erupt in the star's atmosphere, creating bright and hot regions.

The familiarity of Betelgeuse to astronomers doesn't mean the star isn't capable of delivering surprises too. When the team compared images collected in 2023 to observations from 2015, they were surprised to see a hotspot in the northeast of the stellar disk has persisted for at least seven years, that is much longer than predicted by current stellar models.

The orientation of the hotspots of Betelgeuse also added support to the idea that the red supergiant star is orbited by an elusive companion star.

Astronomers will continue to monitor the hotspots of Betelgeuse with ALMA to determine how fixed they are and how their evolution relates to things like mass loss, and the structure of the star's atmosphere.

That investigation will likely continue until Betelgeuse finally ends its life in a supernova explosion.

The team's research has been accepted for publication in the journal Astronomy & Astrophysics and is available on the paper repository site arXiv.

Astronomers have found the fastest known star in the Milky Way, a faint object racing around Sagittarius A*, the supermassive black hole at the heart of our galaxy. Dubbed S301, the star reaches about 15,500 miles (25,000 kilometers) per second at its fastest — more than 8% the speed of light.

"What is special about this star is that it's orbiting Sagittarius A* on a very tight orbit, taking just 8.7 years to complete it, and is approaching the black hole at a mere 12 times the distance of Earth to the sun. That is unprecedented," study author Felix Mang, a Ph.D. student at the Max Planck Institute for Extraterrestrial Physics in Germany, said in a statement.

The discovery gives astronomers a new way to probe the roughly 4.3-million-solar-mass black hole. General relativity predicts that a rotating black hole drags spacetime along with it, an effect known as frame dragging, or Lense-Thirring precession. That distortion should gradually alter S301's orbit — because the star ventures so close to Sagittarius A*, those changes may become measurable within about a decade.

For the first time, we would actually be able to measure very directly the spin of a massive black hole, which would be a key test of Einstein's theory," said study co-author Stefan Gillessen, also of the Max Planck Institute.

Researchers spotted S301 in 2023 using the GRAVITY instrument on the European Southern Observatory's Very Large Telescope Interferometer in Chile, then traced it back through observations from 2021 and 2017. Its highly elongated orbit suggests S301 may once have belonged to a binary system that wandered too close to Sagittarius A*. The black hole could have captured S301 while flinging its companion outward at tremendous speed.

Astronomers plan to keep tracking S301 with GRAVITY+ and, eventually, ESO's Extremely Large Telescope. With its next close pass expected in 2031, observations spanning two full orbits could reveal Sagittarius A*'s spin for the first time.

The team's research was published on August 19 in the journal Nature.

Astronomers have watched a dead star, in the guise of the Helix Nebula, being recycled back into the interstellar gas from which it originally came, bringing the story of that star full circle.

Stars can last for millions, or even billions, of years, but they do not last forever. When a sun-like star reaches the end, it blossoms into a beautiful planetary nebula. The Helix Nebula, located 650 light-years away in the constellation of Aquarius, the Water Bearer, is one such example of a planetary nebula.

The Helix's central star has run out of hydrogen needed for nuclear fusion reactions in its core. This caused the core to begin to contract and raised the temperature in the star's outer layers, which ignited fusion reactions there instead. This had the effect of causing the star to bloat into a red giant. Then, eventually, the outer layers of that red giant detached and expanded into space to form the Helix Nebula. Meanwhile, the star's inert core contracted and became a white dwarf.

As the nebula expands, it gradually disperses into the interstellar medium (ISM), feeding the elements formed within the star back into interstellar gas clouds. These clouds will eventually produce the next generation of stars. However, astronomers had never actually seen the point at which a dead star's remains are absorbed into the ISM — until now.

"We are seeing material shed near the end of a star's life being broken apart and returned to the galaxy," said Yale University's Pieter van Dokkum, who led the study, in a statement. "That hand-off — from recognizable stellar debris to the diffuse gas between the stars — has been very difficult to observe."

Van Dokkum's team were not actually looking for this. Instead, they were conducting routine calibration of a new astronomical instrument called MOTHRA, the Modular Optical Telephoto Hyperspectral Robotic Array at the El Sauce Observatory in Chile. When complete, MOTHRA will be armed with 1,140 telephoto lenses that will scrutinize the night sky while looking for traces of faint gas in the Milky Way galaxy.

Astronomical instruments require calibration before use, and this is accomplished by targeting a familiar object in the sky and tuning the instruments to how that object should appear. The MOTHRA team used the Helix Nebula to calibrate the telephoto lenses that they currently have operational, and that was when they found something unexpected.

"We thought we were taking a calibration image of one of the best-known nebulas in the sky," Roberto Abraham of the University of Toronto said in the statement. "Instead, we found this extraordinary network of bow-shaped structures. It was immediately clear that the faint outer Helix was telling us a story that had largely been missed."

The Helix Nebula appears donut-shaped and has been imaged countless times before by both professional observatories such as the Hubble Space Telescope and James Webb Space Telescope, and by amateur astronomers whose long exposures can reveal an outer halo of gas around the nebula's bright ring. To give an idea of scale, the outer edge of the bright ring is 5.7 light-years across, and the outer halo exists beyond even this.

The team discovered 22 complete or partial arc-shaped clumps of gas in the outer halo. They are called bow shocks and they arise from the motion of something pressing into another medium, in this case clumps of gas that have expanded out from the planetary nebula running into and plowing through the ISM. It is similar to the bow-shaped waves that ride ahead of the prow of a boat in water.

"The shocks change dramatically with distance from the central star," Imad Pasha of Dragonfly Focused Research Organisation, said in the statement.. "Those nearer the center are large, thin and sharply defined. Further out, they become smaller, fuzzier and increasingly fragmented."

This implies a progression, and that the deeper into the ISM the clumps of the star's ejected material press, the more they become eroded and dispersed back into the interstellar gas. The team estimate that material from the planetary nebula can survive for about 10,000 years after encountering the ISM before they are completely shredded and absorbed back into it.

Stars are born from the molecular gas clouds that lie in interstellar space, and these clouds are enriched with the elements produced by fusion reactions within previous generations of stars. Now, thanks to MOTHRA's observations of the Helix Nebula, we have seen these elements being gifted to the Milky Way at large, and in millions or billions of years they will contribute to a new generation of stars, planets and possibly life.

Our own solar system, and Earth along with it, were formed 4.6 billion years ago from elements produced by dead stars. In another five billion years' time, our sun will also exhaust its supply of hydrogen and its fusion reactions will cease, causing it to unfurl into its own planetary nebula.

"Far in the future the sun will go through a similar process and its material will enter the same cycle," says van Dokkum.

All the elements and molecules that make up you and everything around you will be given back to the Milky Way, and one day it will be reborn again and begin the story of a new star system. What will that story bring, we wonder?

The findings from the Helix Nebula were published on Aug. 12 in the journal Nature.

Empty space is not as empty as it looks.

That is the takeaway of a new study examining signals from a dead star, offering what researchers say is the strongest evidence yet that extreme magnetic fields can alter the properties of a vacuum, causing seemingly empty space to act like a prism and changing how light travels through it

The findings, led by Rachael Stewart, a graduate student in physics at the George Washington University, confirm a prediction of a strange effect first proposed 90 years ago.

"The information we obtained from looking at this distant star core also gives us clues about the nature of the fabric of reality as we know it, and I find that to be incredible," Stewart said in a statement.

The idea dates to 1936, when the German physicist Werner Heisenberg and his student Hans Euler proposed that space is never truly void. Instead, they argued, it is a simmering sea of "virtual particles" — electrons and their antimatter counterparts, positrons — that flicker in and out of existence, briefly interacting with their surroundings before vanishing.

This subatomic froth is a consequence of quantum mechanics, and it remains invisible under ordinary conditions. But the theory predicts that an extremely strong magnetic field, such as one around a magnetar, can change how light moves, causing the light's waves to become more strongly aligned in a particular direction in an effect known as "vacuum birefringence."

"Detecting vacuum birefringence requires a magnetic field that is over 100 million times stronger than any we've ever made on Earth," study co-author Marcus Lower, an astrophysicist at the Swinburne University in Australia, said in another statement. "Thankfully, nature has provided us with magnetars, which are the perfect cosmic laboratories to go looking for this effect."

Magnetars are dense, city-size remnants left behind after massive stars explode, hosting the most powerful magnetic fields known in the universe. They are among the rare celestial objects capable of generating fields strong enough to reveal vacuum birefringence, offering scientists an extreme environment to test physics under conditions impossible to replicate on Earth.

"We're not just studying astronomical objects anymore; we're using them to test the laws of nature," study co-author Michela Negro, an astrophysicist at the Louisiana State University, said in a statement.

Astronomers have caught glimpses of this elusive phenomenon before, but not conclusively. In 2017, researchers using the Very Large Telescope in Chile observed polarization hints around a faint neutron star called RX J1856.5-3754, located about 400 light-years from Earth. However, those optical measurements remained open to interpretation, partly due to the challenges of isolating the optical signal.

At the time, scientists noted that definitive proof would require space-based X-ray observatories, specifically NASA's then-forthcoming Imaging X-ray Polarimetry Explorer (IXPE). Launched in 2021, IXPE carries three identical telescopes designed to measure the polarization of high-energy X-rays.

"It's only in the last six or so years that we've actually had a telescope capable of detecting this effect around magnetars," Lower told Michael West Media, an independent news website in Australia.

In March and April 2025, the researchers pointed IXPE at 1E 1547-5408, a magnetar that spins once every two seconds and is unusual among its kind for steadily emitting radio waves. The team supplemented that data with observations from an X-ray telescope aboard the International Space Station, as well as Australia's Murriyang radio telescope and the South African Radio Astronomy Observatory.

According to the study, two findings pointed to vacuum birefringence at work.

First, the X-rays picked up by IXPE were nearly three times more polarized than in similar sources, far higher than standard models of a neutron star's surface emission could explain on their own. Second, the polarization pointed the same way as the star's magnetic field, matching the pattern already observed in its radio waves. The researchers concluded that this combination leaves vacuum birefringence as the only explanation that fits the data.

"It's a bit of a relief because it means that our theories still work and there's nothing broken with physics," Lower told the Michael West Media news site.

For Fernando Camilo, chief scientist at the South African Radio Astronomy Observatory and a co-author of the new paper, the discovery brings a long journey full circle. Camilo has been studying 1E 1547-5408 since 2007, when he first detected its radio waves using the Murriyang dish, revealing its two-second rotation rate.

"At the time 1E 1547 was only the second magnetar in the Milky Way known to emit radio waves, and we were confident that regular monitoring would unveil interesting behaviour," Camilo said in the statement. "However we could never have imagined that 20 years later it would contribute to investigating a fundamental, and particularly quirky, prediction of quantum mechanics."

The team hopes to confirm the finding with data from future missions, including a proposed orbital mission called GoSOX (short for Globe Orbiting Soft X-ray Polarimeter), alongside improved computer simulations to distinguish the vacuum birefringence signal from other processes around magnetars.

"With these future data on hand and our updated simulations, we may finally be able to complete the quest started by Heisenberg nearly 90 years ago," Lower said in the Swinburne University statement.

This research is described in a paper published Aug. 5 in the journal Nature.

Astronomers have captured the death of a massive star from its first faint flash of X-rays, revealing an unusual explosion that may bridge the gap between ordinary supernovas and more extreme, gamma-ray-burst-producing stellar explosions

The event began in March 2026, when China's Einstein Probe spacecraft detected a brief X-ray flash from a galaxy about 500 million light-years away. Follow-up observations identified the source, initially designated EP260321a and later named supernova SN 2026gzf, as a broad-lined Type Ic supernova.

Such explosions occur when massive stars that have lost their outer layers of hydrogen and helium collapse. They are often associated with narrow, powerful jets traveling near the speed of light and, in some cases, brilliant gamma-ray bursts. But SN 2026gzf produced neither.

Instead, the initial X-ray signal appears to have been a "shock breakout" — the moment the blast wave generated by a collapsing star reaches its surface and releases its first burst of radiation. The flash was the faintest shock breakout yet linked to a broad-lined Type Ic supernova, according to the research team.

Because shock breakouts generally last only seconds to hours, astronomers rarely detect them. In this case, rapid observations by a network of space- and ground-based telescopes, including a number of NSF NOIRLab observatories, allowed researchers to follow the supernova across multiple wavelengths throughout its early life.

"Our observations allowed us to study the physics of three pieces of this explosion: the X-ray shock breakout, the accompanying supernova, and the interaction of the supernova with material previously cast out by the dying star," Jillian Rastinejad, who led one study on the event, said in a statement. "With this information we were able to map out the structure of the material surrounding the star and understand the star's violent lifestyle before it collapsed."

The observations suggest that the progenitor was a Wolf-Rayet star born with about 20 times the mass of the sun. Before exploding, it had shed its hydrogen and helium, leaving behind a core composed largely of carbon and oxygen.

Researchers also found evidence of multiple shells of material surrounding the star. Those shells were likely expelled during turbulent bouts of mass loss shortly before the explosion, giving astronomers an unusually detailed view of the star's final stages.

The discovery suggests that energetic, broad-lined Type Ic supernovas do not always produce gamma-ray bursts or relativistic jets. Instead, massive stars may reach similar-looking explosions through a wider variety of pathways than astronomers previously recognized.

"Going forward, I'm excited to observe more shock breakout events in similar detail to test if all stripped stars have a similar 'lifestyle' prior to collapse and what, if any, differences we see," said Gokul Srinivasaragavan, a member of Rastinejad's team.

Astronomers have used the Very Large Telescope (VLT) in the Atacama Desert region of Northern Chile to discover the strongest evidence yet that the famous star Betelgeuse has a companion star. That means after a century of investigation, scientists are closer than ever before to conclusively identifying Betelgeuse as a binary system composed of two stars, Betelgeuse A and Betelgeuse B.

Betelgeuse is a red colored star visible with the naked eye in the constellation of Orion and located around 650 light-years from Earth. Astronomers initially proposed the existence of another star orbiting Betelgeuse around 100 years ago in an attempt to explain the familiar star's strange dimming, which has been observed for over 1,000 years. While other teams have gathered evidence of the existence of Betelgeuse B, this new image is the clearest ever direct observation of the star. The scientists behind the discovery are thrilled.

"This is the conclusion of a century-long quest," team leader Miguel Montargès of the Observatoire de Paris, France, said in a statement. "We have shown that Betelgeuse is not single; it is accompanied by a faint stellar companion. I jumped from my chair when I saw the processed images."

The discovery of this new evidence of Betelgeuse B follows two papers published in 2024 that suggested this elusive stellar companion would be at its furthest from Betelgeuse A in December of that year. With that clue in hand, Montargès and colleagues set about hunting it.

"Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted," Montargès said. "Because it is more massive than predicted, we see it!"

Betelgeuse B had previously been theorized to be around the same mass as the sun, but these new observations reveal that this elusive star has instead around two to three times the mass of our star.

"The fact that we can still discover a nearby companion, more massive and brighter than the sun, around such a well-studied star is remarkable," Montargès added. "These are among the best moments in science: seeing something new, unexpected."

Capturing Betelegeuse B was only possible thanks to the VLT's SPHERE instrument, which features a coronagraph that blocks out the light of a planetary system's star. Combined with the advanced optics on the instrument, this allows scientists to measure the wavelength and polarity of light both coming directly from the star and being reflected off of any nearby planets. But that's not all SPHERE can do.

"It is remarkable to see how SPHERE and advanced post-processing techniques, originally developed to find exoplanets, also excel at detecting a companion around a massive, evolved star like Betelgeuse," team member Anthony Boccaletti, also an astronomer at the Observatoire de Paris, said.

There are still many questions to answer regarding Betelgeuse B. The team still needs to solidly confirm that what they have seen is actually a companion star, and they would also like to know how the presence of this star could shape the future of Betelgeuse A.

This red supergiant star nearing the end of its evolution gained notoriety a few years ago when its sudden and rapid brightening led to speculation it was about to suffer an explosive death.

"To be certain that the companion is really there, we still need to observe it in one year on the other side of the star, but there is very little space left for doubt," Montargès said. "The question is truly open whether this companion is going to have an impact on the evolution of the red supergiant."

The team's research was published on Tuesday (July 28) in the journal Astronomy & Astrophysics.

For the first time, scientists may have discovered a binary system—like the twin suns of the fictional planet Tatooine in "Star Wars"—where both stars exploded as supernovas, a new study finds.

Although Earth may orbit around a single star, more than half of all stars are in systems where two or more suns orbit each other. "When it comes to massive stars, the percentage in multiple systems are even higher," study lead author Miltiadis Michailidis, a postdoctoral fellow at Stanford University in California, told Space.com.

When massive stars burn all their fuel, they can die in giant explosions known as supernovas. These outbursts can briefly outshine all of the other suns in these stars' galaxies. They often leave behind expanding super-hot clouds of debris known as supernova remnants. Astronomers have detected about 300 such remnants in our galaxy to date.

Given how often massive stars are found in binary systems, "one can expect many pairs of massive stars where both will explode as supernovas," Michailidis noted. "However, this has never been observed, until now."

One reason supernova pairs may have escaped attention is that "if the stars are too close together when they exploded, the resulting supernova remnants may look like that from a single explosion," Michailidis explained. Another is that one star going supernova may propel its partner far enough away to hide the fact they were ever a duo, he added.

In the new study, Michailidis and his colleagues investigated a supernova remnant known as IC 443, located about 6,000 light-years from Earth in the constellation Gemini. IC 443 is also known as the Jellyfish Nebula for how it resembles a jellyfish.

IC 443 is one of the most extensively studied supernova remnants in the galaxy because of how shock waves from the supernova have collided with surrounding clouds of gas and dust to create a set of concentric bubble shells, "much like how a drop of water falling on a lake creates circular waves," Michailidis said. "It is very isolated from its surroundings, without many other objects nearby to complicate its very bright emissions."

The scientists analyzed one of IC 443's much dimmer, long-hidden neighbors, dubbed G189.6+3.3. The German-led ROSAT (Roentgen Satellite) mission first discovered G189.6+3.3 in 1994 via its faint X-ray emissions, and the Russian-German Spektrum Roentgen Gamma (SRG) space observatory later clearly detected shell-like structures within G189.6+3.3, suggesting that it was a supernova remnant.

In the new study, the researchers analyzed more than 16 years of data from NASA's Fermi Gamma-ray Space Telescope along with earlier X-ray, optical and radio measurements. They discovered signs that both IC 443 and G189.6+3.3 were both smashing into the same interstellar cloud of hydrogen, revealing they were close together in space, with the centers of their explosions about 30 to 50 light-years apart.

The researchers calculated that the chances of randomly encountering two unrelated supernova remnants at this distance from one another "was about one in 1,000," Michailidis said. "This suggests that our discovery is in fact the first known binary-system supernova pair."

The scientists estimated that G189.6+3.3 was older than IC 443, with the parent star of G189.6+3.3 exploding between 20,000 to 110,000 years ago, while IC 443 was created about 8,000 to 9,000 years ago. The original stars may have been 20 or more times the sun's mass.

These new findings can help shed light on how massive binary stars evolve, interact and die. For instance, further analysis of G189.6+3.3 and IC 443 can reveal how much of a kick the former gave the latter when it died, Michailidis said.

The scientists detailed their findings July 21 in the journal Nature Communications.