AI Helps Astronomers Discover Unprecedented Supernova Caused by Star-Black Hole Interaction

A black hole ripped apart a supernova

Astronomers taking a closer look at a cosmic showdown have spotted a rare, mindbending event 730 million light-years from Earth. After reviewing a massive stellar explosion, researchers believe they spotted a never-before-seen type of supernova that involves a nearby black hole. According to their study published August 13 in the Astrophysical Journal, it may be the first of many other, similar discoveries. Supernovae are some of the most violent moments in the universe. Although there is some room for debate, the events are generally divided into two primary types. A thermonuclear supernova occurs when a low-mass white dwarf at least 8 times smaller than the sun absorbs matter from a companion star until it explodes. Meanwhile, an iron-core collapse supernova happens after a star more than 10 times our sun's mass finally depletes all its fuel and subsequently collapses into a neutron star or black hole. The event detected in 2023, however, doesn't fit neatly into these categories. The saga started two years ago at Caltech's Zwicky Transient Facility located at the Palomar Observatory in San Diego County, California. There, astronomers from Harvard University, the Smithsonian's Center for Astrophysics, and MIT tasked a newly designed machine learning algorithm to scan the night skies for odd explosions in real time. Operators hoped that quickly flagging possible targets in this way could offer vital extra time for ground and space telescope array observations around the world. In July 2023, the AI system sighted one such event, which astronomers classified SN 2023zkd. Although 2023zkd looked like a relatively standard supernova at first glance, it soon defied observers' expectations. After predictably dimming for multiple months, the stellar explosion inexplicably began brightening again. Researchers reviewed previous data about the star system, and learned that prior to going nova, 2023zkd had slowly been brightening for four years. While four years is not long on a cosmic scale, that's much longer than most stars leading up to their demise. Further examinations indicated that the debris shed by the star in that time ultimately shaped the supernova's light emissions. The first brightening event took place as the supernova's blast wave encountered a mass of low-density gas, while the second illumination came from a delayed, slower interaction with a disk-like cloud of thicker gas. Taken together, it was clear a nearby object had generated an intense gravitational pull on the star before it detonated. "2023zkd shows some of the clearest signs we've seen of a massive star interacting with a companion in the years before explosion," astronomer V. Ashley Villar said in a statement. And across the known universe, there's really only one type of cosmic object capable of such immense gravitational influences. "Our analysis shows that the blast was sparked by a catastrophic encounter with a black hole companion, and is the strongest evidence to date that such close interactions can actually detonate a star," added study lead author Alexander Gagliano. However, there is another potential scenario,one in which the star never even lived long enough to reach supernova status by itself. The study's authors say it's also possible that the black hole simply ripped 2023zkd apart before it got the chance to explode on its own time. Instead, the black hole began devouring the star, which eventually sparked a supernova after its debris collided with the surrounding gas. "We're now entering an era where we can automatically catch these rare events as they happen, not just after the fact," said Gagliano. "That means we can finally start connecting the dots between how a star lives and how it dies, and that's incredibly exciting." No matter the actual flashpoint, the cosmic battle had a clear winner: what now remains is a single, much heavier black hole. "We think this might be part of a whole class of hidden explosions," said Villar.

AI helps astronomers make a potentially major find -- an exploding star being attacked by a black hole

Artificial intelligence has helped astronomers observe what may be the first known case of a star exploding while interacting with a black hole, a new study reports. (Image credit: Melissa Weiss/CfA) Astronomers have observed what may be the first known case of a massive star exploding while interacting with a black hole, marking a discovery that could reveal an entirely new class of stellar explosions. The event, named SN 2023zkd, was first spotted in July 2023 by the Zwicky Transient Facility in California. Located in a galaxy with little ongoing star formation about 730 million light-years away, it was detected by a new artificial intelligence (AI) system built to flag unusual cosmic events in real time. The early alert allowed telescopes worldwide and in space to begin observations immediately, capturing the event from its earliest stages, according to a statement. "2023zkd shows some of the clearest signs we've seen of a massive star interacting with a companion in the years before explosion," Ashley Villar, an assistant professor of astronomy at Harvard University in Massachusetts and a co-author of the new study, said in the statement. "We think this might be part of a whole class of hidden explosions that AI will help us discover." At first, SN 2023zkd appeared to be a typical supernova: a bright flash signaling the death of a massive star that slowly fades over time. But months later, astronomers noticed it brightened again. Looking back at archival data, they found the system had been gradually increasing in brightness for about 1,500 days -- roughly four years -- before the explosion. Such a long-lived pre-explosion phase is rarely seen, and it suggests the star was under intense gravitational stress. The researchers say the most likely explanation is the star was locked in orbit with a black hole. Evidence from light curves and spectra indicates the star underwent two major eruptions in the years before it died, shedding large amounts of gas. The explosion's first light peak came when the blast wave struck low-density material, while the second peak months later was caused by a slower, sustained collision with a dense, disk-shaped cloud. Over time, the black hole's gravity could have destabilized the star, pushing it to collapse. Another possibility, the team believes, is the black hole destroyed the star before it could explode naturally. In that case, the debris would have produced the supernova's light as it crashed into surrounding gas. In either scenario, the aftermath would be a single, heavier black hole. SN 2023zkd "is the strongest evidence to date that such close interactions can actually detonate a star," study lead author Alexander Gagliano, a researcher at the Institute for Artificial Intelligence and Fundamental Interactions, said in the statement. "We've known for some time that most massive stars are in binaries, but catching one in the act of exchanging mass shortly before it explodes is incredibly rare." The findings highlight how AI can spot rare cosmic events in time for detailed study, the astronomers say. They also point to the role upcoming facilities such as the Vera C. Rubin Observatory will play over the next decade, thanks to its ability to document the entire southern sky every few nights from its vantage point in the Chilean Andes mountains. Combined with real-time AI detection, observations gathered by the Rubin Observatory will enable astronomers to identify and study more of these rare, complex events, helping to build a clearer picture of how massive stars live and die in binary systems. "We're now entering an era where we can automatically catch these rare events as they happen, not just after the fact," Gagliano said in the statement. "That means we can finally start connecting the dots between how a star lives and how it dies, and that's incredibly exciting." This research is described in a paper published Wednesday (Aug. 13) in the Astrophysical Journal.

New type of supernova detected as black hole causes star to explode

WASHINGTON, Aug 14 (Reuters) - Astronomers have observed the calamitous result of a star that picked the wrong dance partner. They have documented what appears to be a new type of supernova, as stellar explosions are known, that occurred when a massive star tried to swallow a black hole with which it had engaged in a lengthy pas de deux. The star, which was at least 10 times as massive as our sun, and the black hole, which had a similar mass, were gravitationally bound to one another in what is called a binary system. But as the distance separating them gradually narrowed, the black hole's immense gravitational pull appears to have distorted the star - stretching it out from its spherical shape - and siphoned off material before causing it to explode. "We caught a massive star locked in a fatal tango with a black hole," said astrophysicist Alexander Gagliano of the U.S. National Science Foundation's Institute for AI and Fundamental Interactions located at the Massachusetts Institute of Technology, a co-author of the study published this week in the Astrophysical Journal, opens new tab. "After shedding mass for years in a death spiral with the black hole, the massive star met its finale by exploding. It released more energy in a second than the sun has across its entire lifetime," Gagliano added. The explosion occurred about 700 million light-years from Earth. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). "The gravitational pulls of the two objects were actually similar because we think they had similar masses. But the star was much larger, so it was in the process of engulfing the black hole as the black hole pulled material off of it. The star was large but puffy, and the black hole was small but mighty. The black hole won out in the end," Gagliano said. The researchers are not certain of the exact mechanism that caused the supernova. "It's unclear if the distortion triggers an instability that drives the collapse of the star, and then the leftover stellar material gets rapidly eaten by the black hole, or if the black hole completely pulls the star apart before it goes supernova," said Harvard University astrophysicist and study lead author Ashley Villar. "The star has been pulled and morphed by the black hole in complex ways," Villar added. The binary system started out with two massive stars orbiting each other as cosmic companions. But one of the two stars reached the end of its natural life cycle and exploded in a supernova, and its core collapsed to form a black hole, an extraordinarily dense object with gravity so strong that not even light can escape. "This event reveals that some supernovae can be triggered by black hole companions, giving us new insights into how some stars end their lives," Villar said. Stars that are at least eight times as massive as the sun appear destined to end their lives with a supernova. Those with a mass at least 20 times that of the sun will form a black hole after the explosion. An artificial intelligence algorithm designed to scan for unusual explosions in the cosmos in real time first detected the beginnings of the explosion, providing an alert that enabled astronomers to carry out follow-up observations immediately. By the time the explosion was completed, it had been observed by numerous ground-based and space-based telescopes. "Our AI algorithm allowed us to launch a comprehensive observational study early enough to really see the full picture for the first time," Gagliano said. Observations of the star dating to four years before the supernova revealed bright emissions that the astronomers believe were caused when the black hole guzzled material sucked off the star. For instance, the star's outer hydrogen layer appears to have been ripped off, exposing the helium layer below. The researchers observed bright emissions in the explosion's aftermath as the black hole consumed leftover stellar debris. In the end, the black hole became more massive and more powerful. Systems grouping two or more companions are quite common. Some of these multiples have a black hole as one of the companions. "Our takeaway is that the fates of stars are incredibly impacted by their companion - or companions - in life. This event gives us an exciting window into how dramatically black holes can impact the deaths of massive stars," Gagliano said. Reporting by Will Dunham, Editing by Rosalba O'Brien Our Standards: The Thomson Reuters Trust Principles., opens new tab

Spotify-like AI helps discover never-before-seen supernova as greedy star attempts to eat a black hole

An artist's impression of the events leading up to supernova SN 2023zkd, which likely occurred when a star attempted to swallow a nearby black hole. Here, the star's shape is stretched by the black hole's massive gravitational forces. (Image credit: Melissa Weiss/CfA) Scientists may have spotted a never-before-seen kind of supernova, after using a Spotify-like artificial intelligence (AI) to scan the skies for strange activity. The AI unearthed signs of what could have been a huge star blowing up just as it was attempting to gulp down a nearby black hole. The stellar explosion, dubbed SN 2023zkd, was spotted in July 2023 with the Zwicky Transient Facility, a full-sky astronomical survey based at the Palomar Observatory in California. But Zwicky didn't find the explosion through happenstance. Rather, it was guided to the right spot using an algorithm optimized to find weird night-sky activity. Spotting the signs of a supernova early is key to catching how supernovas start, evolve and then fade away -- providing insight into how these explosions work. In this case, the AI found unusual brightenings months before the explosion happened, study co-lead authors Alex Gagliano, a postdoctoral researcher at the Institute For AI and Fundamental Interactions, and Ashley Villar, a supernova researcher and assistant professor at the Harvard-Smithsonian Center for Astrophysics, told Live Science in an email. This quick alert enabled a number of large observatories to get in on the action and provide observations across a large spectrum of wavelengths. Related: 2 'new stars' have exploded into the night sky at once -- potentially for the first time in history While there are a couple of ideas about what these telescopes actually saw, the scientists behind the new study say the explosion was most likely from a huge star orbiting the black hole. As these two objects tugged at each other, the separation between them decreased. Eventually, the star attempted to consume the black hole and exploded in the process, due to gravitational stress. Alternatively, it could have been that the black hole shredded the star via a process known as "spaghettification," causing the explosion, but the data does not suggest that as strongly, Gagliano said. By looking at the massive star's chemical composition, the team also found that it had not lost all of its outermost material before it exploded. "This suggests that binary interaction is a lot messier than astronomers have thought," Gagliano said. "Upcoming events will tell us how the explosions of massive stars are shaped by companion interaction, which is very difficult to model at present." Gagliano cautioned that nobody has seen enough of these explosions to fully predict how a huge star and a black hole might interact. The data, however, is "very hard to explain without a binary system," meaning that a black hole and star were very likely involved in some way. The AI used in the discovery is called Lightcurve Anomaly Identification and Similarity Search (LAISS). The astronomy AI is based on the Spotify algorithm, so LAISS recommends astronomical observations in a similar way that Spotify users are guided to songs they may enjoy. The latest explosion came to the attention of LAISS due to properties from the light of the binary system, and its location 730 million light-years from Earth. Features of SN 2023zkd were "compared against a large reference dataset of known objects to identify statistical outliers," Gagliano said. "Anomalous signals may indicate rare or previously unseen phenomena." Once LAISS finds something interesting, a bot in Slack, an instant messaging service, flags candidates and posts them into a dedicated channel, enabling team members to check out the findings in real time. "This streamlined system enables astronomers to rapidly target the most promising and unusual discoveries," Gagliano said. After the explosion, the light pattern of SN 2023zkd became very strange. At first it brightened just like a typical supernova, then declined. But astronomers really began to pay attention when it brightened once again. Archival data showed more strange behavior: The star, which had been at a consistent brightness for a while, was gradually getting brighter in the four years before it exploded. Astronomers think the light comes from the excess material the star was shedding. At first, it got brighter as the shockwave from the supernova plowed into lower-density gas in the region. Another brightness peak later came as the shockwave continued into a cloud of dust. As for the presence of the black hole, astronomers inferred it both from the structure of the gas and dust, as well as the strange stellar brightening in the years before the explosion. LAISS helped astronomers to see all this extra detail. "If we had waited until a human flagged 2023zkd, we would have missed the early signatures of the surrounding disk and the existence of a black hole companion. AI systems like LAISS help us regularly find rare explosions, without relying on luck, and early enough to uncover their origins," Gagliano said.

Star Tries to Swallow a Black Hole, Ignites One of the Strangest Supernovas Ever Seen

The unusual interaction triggered a strange new type of supernova that appeared to explode twice. Black holes are dark, menacing objects with gravity so intense that not even light can escape, so you don't want to mess with them. A recent discovery of one of the strangest supernovas ever observed reveals the tragic story of a star that tried to defy the powerful pull of a nearby black hole but later conceded in an explosive death. A team of astronomers discovered the unusual supernova, dubbed SN 2023zkd, while digging through observations of particularly interesting targets gathered by telescopes around the world. The stellar explosion may have been sparked by a deadly encounter with a black hole, leading to the untimely detonation of the star. The discovery, detailed in a new paper published in the Astrophysical Journal, marks the strongest evidence to date of cosmic interactions between stars and black holes that may lead to supernova. The Zwicky Transient Facility in Southern California discovered this particular supernova in July 2023, and it was later flagged by an artificially intelligent algorithm trained to alert the team every morning to the most unusual stellar explosions found in the collective data. The bot flagged the supernova as it appeared to be "evolving in an odd way," Alexander Gagliano, a fellow at the National Science Foundation's Institute for Artificial Intelligence and Fundamental Interactions and lead author of the study, told Gizmodo. "There are two particularly strange features of this supernova," Gagliano said. It "looks like it exploded twiceâ€"it brightened, dimmed, then brightened again!" Although there was only one explosion, the unusual evolution of the supernova was the first clue that it had originated from a complex environment. "Second, normally the start of that explosion is quite fast (it takes maybe a few days to a month to reach its peak brightness)," Gagliano added. "In this case, we actually dug deeper into the data before the supernova and noticed that the star was clearly brightening slowly for years prior to its death." The team combined the unusual nature of the supernova along with other evidence to trace the origin story of the explosion and found that it points to a star merging with a black hole companion. The astronomers behind the discovery believe that the massive star was locked in a deadly orbital dance with the black hole. As the two objects were drawn closer to one another, the star partially swallowed the black hole. That led to gravitational stress imposed upon the star, which then triggered the supernova explosion. Another possible scenario is that the black hole completely tore the star apart before it could explode on its own, according to the paper. If it did, the black hole would have pulled in the debris shed by the star, which would have crashed into the gas surrounding the black hole and triggered a supernova emission. Either way, the black hole was left standing while the star suffered an explosive death. "LAISS, the AI system responsible for catching SN 2023zkd, works by extracting properties from both the supernova’s light and the supernova’s home (its galaxy). These features are then compared against a large reference dataset of known objects to identify statistical outliers," Gagliano said. "Anomalous signals may indicate rare or previously unseen phenomena." A specialized Slack bot then posts the outliers in real time to a channel, and team members review the list of candidates every morning to coordinate follow-up observations. Using the AI system, the team is still on the hunt for more exotic phenomena and strange anomalies. "It’s a very exciting time to study supernovae," Gagliano said.

Astronomers may have observed star's death while devouring a black hole

Concept of an explosive interaction between a black hole and a nearby massive star The supernova known as SN 2023zkd was first spotted in July 2023 by the Zwicky Transient Facility, but what made it remarkable was how quickly astronomers were able to study it. A newly developed AI algorithm, designed to flag unusual stellar explosions in real time, raised the initial alert. That early detection proved crucial, giving scientists the chance to launch immediate follow-up observations with an array of telescopes on Earth and in space. Leading the effort were researchers from the Center for Astrophysics at Harvard & Smithsonian (CfA) and MIT, working under the Young Supernova Experiment.

How AI helped astronomers uncover one truly weird supernova

The new case, soon to be published in The Astrophysical Journal, supports the idea that massive stars don't just explode when they get old. Dramatic space collisions may trigger at least some of these fatal blasts, too. To find the exotic supernova, dubbed SN 2023zkd, astronomers used a new artificial intelligence algorithm tied to a Slack bot to scan for unusual explosions in real time. Called the Light curve Anomaly Identification and Similarity Search, the tool's prompt notification gave them enough of a lead to plan and execute large telescope observations before the explosion faded out. Scientists have used classic AI methods like this for decades to help sift through heaps of data, said V. Ashley Villar, an assistant professor of astronomy at Harvard, especially in the age of robotic telescopes, which spot thousands of flickering lights nightly. But nowadays, generative AI, which can learn from data, is becoming increasingly helpful, said Villar, an author of the paper. "Our research group has embraced these new technologies to help us in our daily tasks: classifying stellar explosions, inferring physical properties of stars quickly, and even identifying exciting new systems like 2023zkd," she told Mashable. "We do this by carefully integrating our astrophysical knowledge and sanity-checking responses from AI systems." The explosion, about 730 million light-years away from Earth, was first detected in July 2023 by the Zwicky Transient Facility, a robotic telescope partly funded by the U.S. National Science Foundation in California. What made this event unusual was that it didn't have just one burst of light, but two, spaced about eight months apart. And that wasn't the only surprise. After digging through the archives, researchers found that the source had been gradually increasing in brightness before it detonated. That kind of ramp-up to a supernova is not the status quo, the researchers said. Half a century ago, black holes were an idea on paper that even leading scientists doubted. Now they're firmly established in astronomy. The most common type, stellar black holes, form when a massive star ends its life in a supernova, collapsing its remaining material into a dense, compact object, from which no light escapes. Unlike planets or stars, black holes don't have a surface. Instead, they're surrounded by an "event horizon," the ultimate point of no return, where anything crossing it is trapped forever by gravity. It's possible the black hole ravaged the star before it could blast apart. If that were the case, the black hole might have reeled in the stellar material, causing the debris to smash into surrounding gas, which then sparked a supernova emission. But the simplest explanation for what happened is that a massive helium-rich star was in a close orbit with a companion black hole, each perhaps 10 times more massive than the sun. When they began to merge, the event triggered the supernova, according to The Harvard & Smithsonian Center for Astrophysics and MIT, who led the study as part of the Young Supernova Experiment. That project is a sky survey to catch the explosions immediately after their onset. The AI tool flagged the event months before its most unusual behavior, said Alexander Gagliano, another author of the upcoming paper. "Both the star and the black hole 'feel' one another's gravitational pull. In one sense, the black hole is 'swallowed' by the hot gas of the star, which is sloshing around the system," Gagliano told Mashable. "But in another sense, the black hole is responsible for the ultimate destruction of the star." Here's how the LAISS AI tool worked: Each supernova source is broken down by its features, such as its color, duration, and peak brightness, as well as by its host galaxy's characteristics. Those components go into a database for an algorithm to review for events that are statistically abnormal. About half of the supernovas it flags are genuinely weird. Another roughly 25 percent turn out to be active supermassive black holes at the centers of galaxies, which are not what the researchers are looking for. Though the tool turns up a lot of events they don't want, it at least narrows them down to a more manageable list for further vetting, said Gagliano, an Institute for Artificial Intelligence and Fundamental Interactions fellow. That being said, the new Vera C. Rubin Observatory, which scientists expect will exponentially increase the number of supernova detections, will require even more creative and selective solutions for sorting through the data. "More recently, we've been moving to more 'modern' AI methods to extract less interpretable but more flexible features from images of the supernova galaxies," Villar said. Fun fact: The LAISS tool also has the capability to find and group similar supernovas. To do this, it relies on ANNOY, an open-source Spotify algorithm -- except instead of recommending songs with similar vibes, it suggests astronomical events. Now you might be wondering: When a massive star goes supernova, it typically collapses into a black hole. But what happens when a star goes supernova because of its interaction with a black hole? "A larger black hole is what remains," Gagliano said.

There's Something Really Suspicious About the Way This Star Died

Stellar death is a complex and mysterious process -- but in the case of a supernova known as 2023zkd, things were more gruesome than any astronomer had ever seen before. As its name suggests, this supernova -- the fabulous astronomical term for the explosive death of a star -- was first spotted back in 2023, when Southern California's Zwicky Transient Facility zeroed in on it thanks to new AI algorithms designed to detect such brilliant blasts. This supernova, however, was different. It appeared, as explained in a statement by researchers, to be dangerously close to a small black hole -- but instead of being ripped asunder, it seems that the supernova began trying to feast upon that which should have destroyed it. Wait, what? In a new paper published in the Astrophysics Journal explains, scientists from Harvard, the Smithsonian, and the Massachusetts Institute of Technology were taken aback by what they were seeing from 730 million light-years away. Black holes and supernovae are not, as paper author and Harvard professor Ashley Villar told the Washington Post, all that unusual to witness in proximity. Both were once, presumably, stars, and some theories suggest supernovae may even be part of the building blocks for black holes. In the case of SN 2023zkd, things seemed to go haywire long before its gluttonous dance with its black hole partner. The scientists' algorithm initially detected the expected bright burst of light from the supernova -- but looking back on archival data, they found that it had actually been brightening slowly for roughly four years, which is much longer than typically seen in supernovae. Even more curiously, SN 2023zkd then brightened unexpectedly while astronomers observed its progress moving forward -- a "dramatic re-brightening," as the Center for Astrophysics' statement called it, that seemed to be related to the "thick, disk-like" cloud that was seen near the site of the explosion. "We think that the light source is actually from stuff hitting each other as it's trying to escape," Villar told WaPo. "That explosion hits that disk, and now we're seeing all this additional light." All that escapee debris was, per one theory, looking to get out from the gravitational stress of the supernova's black hole companion. If further analysis confirms this to be the case, it will make this unique supernova activity "some of the clearest signs we've seen of a massive star interacting with a companion in the years before explosion," Villar said in the statement -- a euphemistic way of suggesting that it would be the first time scientists have ever seen a supernova try to eat a black hole. While there's a good chance that scientists have seen the aftermath of such strange exchanges between these two types of former stars, technologies like the AI used to find SN 2023zkd will make it all the easier to catch them in the act. "We're now entering an era where we can automatically catch these rare events as they happen, not just after the fact," explained Alexander Gagliano, another of the study's authors and a fellow at the National Science Foundation's Institute for Artificial Intelligence and Fundamental Interactions, in the statement. "That means we can finally start connecting the dots between how a star lives and how it dies, and that's incredibly exciting."

AI Helps Astronomers Discover a New Type of Supernova | Newswise

Newswise -- Astronomers have discovered what may be a massive star exploding while trying to swallow a black hole companion, offering an explanation for one of the strangest stellar explosions ever seen. The discovery was made by a team led by the Center for Astrophysics | Harvard & Smithsonian (CfA) and the Massachusetts Institute of Technology (MIT) as part of the Young Supernova Experiment. The blast, named SN 2023zkd, was first discovered in July 2023 by the Zwicky Transient Facility. A new artificial intelligence algorithm designed to scan for unusual explosions in real time first detected the explosion, and that early alert allowed astronomers to begin follow-up observations immediately -- an essential step in capturing the full story of the explosion. By the time the explosion was over, it had been observed by a large set of telescopes, both on the ground and from space. The scientists think the most likely interpretation is that the massive star was locked in a deadly orbit with the black hole. As energy was lost from the orbit, their separation decreased until the supernova was triggered by the star's gravitational stress as it partially swallowed the black hole. "Our analysis shows that the blast was sparked by a catastrophic encounter with a black hole companion, and is the strongest evidence to date that such close interactions can actually detonate a star," said Alexander Gagliano, lead author of the study and fellow at the NSF Institute for Artificial Intelligence and Fundamental Interactions. "Our machine learning system flagged SN 2023zkd months before its most unusual behavior, which gave us ample time to secure the critical observations needed to unravel this extraordinary explosion." An alternative interpretation considered by the team is that the black hole completely tore the star apart before it could explode on its own. In that case, the black hole quickly pulled in the star's debris and supernova emission was generated when the debris crashed into the gas surrounding it. In both cases, a single, heavier black hole is left behind. Located about 730 million light-years from Earth, SN 2023zkd initially looked like a typical supernova, with a single burst of light. But as the scientists tracked its decline over several months, it did something unexpected: it brightened again. To understand this unusual behavior, the scientists analyzed archival data, which showed something even more unusual: the system had been slowly brightening for more than four years before the explosion. That kind of long-term activity before the explosion is rarely seen in supernovae. Detailed analysis revealed that the explosion's light was shaped by material the star had shed in the years before it died. The early brightening came from the supernova's blast wave hitting low-density gas. The second, delayed peak was caused by a slower but sustained collision with a thick, disk-like cloud. This structure -- and the star's erratic pre-explosion behavior -- suggest that the dying star was under extreme gravitational stress, likely from a nearby, compact companion such as a black hole. "2023zkd shows some of the clearest signs we've seen of a massive star interacting with a companion in the years before explosion," said V. Ashley Villar, a CfA assistant professor of astronomy in the Harvard Faculty of Arts and Sciences and a co-author on the study. "We think this might be part of a whole class of hidden explosions that AI will help us discover." "This discovery shows how important it is to study how massive stars interact with companions as they approach the end of their lives," said Gagliano. "We've known for some time that most massive stars are in binaries, but catching one in the act of exchanging mass shortly before it explodes is incredibly rare." With the Vera C. Rubin Observatory recently unveiling its first images and preparing to survey the entire sky every few nights, this discovery marks a glimpse of what's to come. Powerful new observatories, combined with real-time AI systems, will soon allow astronomers to uncover many more rare and complex explosions and begin to map how massive stars live and die in binary systems. The Young Supernova Experiment will continue to complement Rubin by using the Pan-STARRS1 and Pan-STARRS2 telescopes to identify supernovae shortly after explosion. This approach offers a cost-effective way to study the dynamic nearby universe. "We're now entering an era where we can automatically catch these rare events as they happen, not just after the fact," said Gagliano. "That means we can finally start connecting the dots between how a star lives and how it dies, and that's incredibly exciting." The authors used data from a large number of telescopes including NASA's Neil Gehrels Swift Observatory, the Panoramic Survey Telescope and Rapid Response System, the Asteroid Terrestrial-impact Last Alert System, and a suite of telescopes across the Magellan, MMT, and Las Cumbres Observatories. The Young Supernova Experiment is a collaboration among University of California Santa Cruz, DARK Cosmology Centre, University of Illinois, and principal investigators Vivienne Baldassare (Washington State University), Maria Drout (University of Toronto), Kaisey Mandel (Cambridge University), and V. Ashley Villar (Harvard). These results are being published in the latest issue of the Astrophysical Journal.

A peculiar supernova prompts new theories about the cosmos

Scientists think a gigantic dying star tried to swallow a black hole. It didn't end well for the star, a new study says. A new discovery about what happens when a supernova - an exploding star - and a black hole collide could change the way scientists understand the lives and deaths of stars. The finding was the first time astrophysicists have observed a giant star exploding as the result, they believe, of its interaction with a dense black hole. The supernova was triggered by the intense gravitational stress of trying to "swallow" the black hole up, the study's authors say. The phenomenon may happen more than scientists realize, and new tools to observe supernova explosions could reveal other instances of black holes sparking supernovas, according to the lead study author. "If that is much more common, then it would transform the way we think about how stars explode," said Alex Gagliano, lead author of the study and fellow at the National Science Foundation Institute for Artificial Intelligence and Fundamental Interactions. One of the coolest parts of the discovery is that it was made possible by the use of artificial intelligence, or AI, Gagliano said. AI helped flag a star behaving unusually early on, which allowed the team to closely monitor as a surprising event unfolded. The study, published in the Astrophysical Journal, was conducted by a team led by the Center for Astrophysics, a collaboration between Harvard and the Smithsonian, and the Massachusetts Institute of Technology. It was part of the Young Supernova Experiment, which hopes to discover thousands of new cosmic explosions. What is a supernova? A black hole? A supernova is the spectacular explosion of a gigantic dying star. Stars - giant balls of gas - all have a life cycle, which can range from millions to trillions of years, according to NASA. When a huge star, several times the mass of the Sun, runs out of its nuclear fuel at its center, gravity's force takes over and it suddenly collapses, creating shock waves that cause the outer part of the star to explode into a supernova. A supernova typically leaves behind a very dense core. The very largest supernovas leave behind black holes, infamous for their great mystery. Black holes are points in the universe where gravity is so strong that nothing, not even light, can get out, NASA says. Their gravity is so strong because matter is squeezed into a tiny space. Because no light can escape, black holes are invisible, but scientists can spot evidence of them when they suck in matter and gas, which glow as they near the black hole. Sometimes black holes are observed to have companion stars, stars that orbit around them. That's the interaction researchers zeroed in on in this new discovery. Why is this exploding star so special? The discovery of the supernova dubbed SN 2023zkd was so unusual because it put together pieces of a puzzle that had never been seen together before, Gagliano said. Usually, a supernova explosion gets brighter over a period of a week or two before reaching its peak and then gets dimmer, he said. At first, SN 2023zkd looked like a typical supernova explosion, just a sudden peak of brightness. But it dimmed at an unusually slow rate afterward, causing an AI program to flag it for further study. Scientists watched its decline for months, and then came a very strange behavior: It began to brighten again in a second peak. To understand this, the researchers looked back at old archival data and discovered that before its first blast, the star had been slowly brightening for a period of about four years, an incredibly uncommon sight. All these factors combined pointed to one likely explanation. About 730 million light-years from Earth, SN 2023zkd had been a star locked in an orbital dance with a black hole, and as they gradually got closer to one another, the black hole pulled at the star's material, causing the gradually increasing glow, Gagliano said. At the moment of the explosion, the star and black hole became so close that the star couldn't survive anymore, he said. The extreme gravitational stress from the black hole caused the supernova explosion. The second peak of brightness happened when the explosion itself collided with a disc-like cloud of dust and gas leftover from the interaction between the star and the black hole. "It's been known for a long time that the majority of stars have companions that interact with them at some point during their lives... but we never really thought that this interaction played a leading role in driving the death of a star," Gagliano said. "That is something that is very new and exciting and I think will force us to revisit how we think about simulating the end of a star." How AI is helping astrophysicists make new discoveries The explosion was first discovered in July 2023, after the research team was alerted to unusually slow dimming of the glow of a supernova. The alert came from an AI program designed to scan the sky for all the supernovas and each morning report on any unusual activity. The alert allowed the researchers to continue to observe the supernova and see as it shockingly began to brighten again, indicating a second explosion. Were it not for the AI program, the initial explosion may have just looked observationally like many other supernovas and scientists would never have looked back to see its slow brightening and deduced that it was interacting with a black hole, Gagliano said. AI's role in sifting through mountains of data that human researchers can't and flagging anomalies is growing in several scientific fields, from medicine to astrophysics, Gagliano said. "One of the only reasons that we were able to make this discovery and understand how scientifically interesting it was was through the combination of researchers in machine learning and in astrophysics," he said.

Astronomers Observe Rare Supernova-Black Hole Interaction in Early Stages

AI detection may reveal more rare and dramatic stellar death events Astronomers identified the earliest stages of three cosmic explosions for the first time, a dazzling type of blast called a supernova, through years of observations with radio telescopes and extensive monitoring from a fleet of ground- and space-based telescopes. Known as SN 2023zkd, the explosion was initially discovered in July 2023 with the Zwicky Transient Facility in California. It first appeared as a standard supernova light, appearing to indicate the sudden demise of a giant star in a collapse that fades away quickly. A few months later, however, astronomers discovered it glowing in full strength once more. Possible Black Hole Connection According to As per Space, a recently published paper in the Astrophysical Journal argues that it may have been in an orbit with a black hole. Its light curves and spectra indicated that it underwent two massive outbursts before its death, ejecting tenths of a solar mass of gas. Two Distinct Brightness Peaks After all, the first increase in brightness occurred when the blast wave passed through a low-density material, and then, a few months later, it took a prolonged collision with high spatial disk clouds to recover. The gravity of it could have pulled it toward the star and then destabilised it, leading to collapse. Alternative Theory: Black Hole Tidal Destruction Another theory is that the blackhole ripped the star a long distance before exploding naturally. Then supernova light began when that debris smacked into the as around it. In either case, a single black hole would still be forged after the event had ended. Unlocking Rare Stellar Events with AI The explosion of SN 2023zkd provides the best evidence of such an event happening in a very close encounter, prompting a star to explode, a previously believed-to-be exceedingly rare occurrence. The above capability, when combined with real-time AI detection, will unlock a much larger volume of these rare and exciting events to be discovered and studied, directly connecting the life of a star to its dramatic death in more detail than ever before.