Read More: Samples from the asteroid Bennu force us to rethink the origin of life: NASA finds key compounds in rocks over 4.5 billion years old<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nFor most of us, they are distant fireworks, but for astronomers they are one of the best tools to probe how stars live and die far across the cosmos.<\/p>\n\n\n\n
Catching a seven-hour burst<\/h2>\n\n\n\n
So what made this event so unusual? To start with, its sheer length. Based on combined data from several space-based detectors, scientists estimate that the gamma ray phase of GRB 250702B lasted roughly twenty five thousand seconds. <\/p>\n\n\n\n
For comparison, a typical long gamma ray burst runs out of steam in tens of seconds, and even the previous record holder, GRB 111209A, \u201conly\u201d stayed bright for about fifteen thousand seconds.<\/p>\n\n\n\n
The signal also came in several separate flashes, detected multiple times by the Gamma ray Burst Monitor on board the Fermi Gamma ray Space Telescope<\/a> and other instruments. That pattern told researchers they were not seeing a series of unrelated events, but one long-lived engine switching on and off while it fed on nearby fuel.<\/p>\n\n\n\nFrom collapsing stars to cosmic outliers<\/h2>\n\n\n\n
Up to now, most long gamma ray bursts have been explained by two main scenarios. In the first, a massive, rapidly spinning star collapses into a black hole, launching narrow jets that punch through the dying star and light up the sky. <\/p>\n\n\n\n
In the second, two neutron stars or a neutron star and a black hole spiral together and merge, again driving a short, violent jet.<\/p>\n\n\n\n
Both processes can produce enormous energy, but they are limited by how much material can fall in and how fast. Even in extreme cases, models suggest the engine should shut down after a few thousand seconds. <\/p>\n\n\n\n
GRB 250702B kept going far longer than that, and with sub-second flickers that point to a compact, stellar mass object at its core rather than a supermassive black hole in a galactic center.<\/p>\n\n\n\n
That left astronomers in an interesting spot. The burst looked like it came from a stellar mass black hole, but its duration did not match any standard recipe.<\/p>\n\n\n\n
A black hole falls into a star<\/h2>\n\n\n\n
The new study, led by Eliza Neights of NASA\u2019s Goddard<\/a> Space Flight Center, argues that the best explanation is a so-called helium merger. <\/p>\n\n\n\nIn this scenario, a black hole roughly the mass of a star orbits a stripped helium star that has already lost its outer hydrogen layers. As the helium star expands late in its life, the black hole spirals inward, dives into the star\u2019s envelope and begins to tear it apart from within.<\/p>\n\n\n\n![\"An](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/04\/grb-250702b-longest-gamma-ray-burst-astronomy-1.jpg\" "\\"\\"")
The record-breaking gamma-ray burst GRB 250702B lasted approximately 25,000 seconds, suggesting a rare “helium merger” where a black hole shreds its companion star from the inside.<\/figcaption><\/figure>\n\n\n\nWhen that happens, a huge amount of orbital angular momentum is dumped into the infalling material. Instead of crashing straight into the black hole, the gas forms an extended disc that can feed the central engine for many hours. The result is a long-lived, ultra-relativistic jet that we see as an ultra-long gamma ray burst.<\/p>\n\n\n\n
\n\n\nRead More: Astronomers confirm for the first time the existence of a giant volcanic cave on Venus<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nFor GRB 250702B, follow up observations in X-ray, infrared and radio light showed an afterglow coming from a dusty, star-forming region in a distant galaxy, well away from its central black hole. The energy in the jet looks fairly normal for a long burst once you account for how narrowly it was focused, but it was spread over a much longer time. <\/p>\n\n\n\n
That combination fits naturally with a helium merger, where the total fuel supply is similar to a classic collapsar, just delivered more slowly. It also links this record breaker to other events where gamma ray bursts and unusual supernovae seem to go hand in hand.<\/p>\n\n\n\n
Why we are only seeing these giants now<\/h2>\n\n\n\n
If helium mergers are possible, why have we not seen more of these ultra-long bursts? One reason is simple observing bias. Most gamma ray monitors in space are designed to spot short, sharp flashes that stand out clearly above background noise. <\/p>\n\n\n\n
Ultra-long bursts are fainter at any given moment and can be interrupted by the Earth blocking the view, so they are easy to miss or misclassify.<\/p>\n\n\n\n
In this case, scientists had help from a network of instruments, including the Konus Wind experiment far from Earth, X ray scanners like MAXI on the International Space Station, and even the Psyche spacecraft\u2019s gamma ray and neutron detector, which happened to be in the right place to see part of the event. <\/p>\n\n\n\n
Putting all those pieces together was a bit like reconstructing a very long, very glitchy power outage from security cameras across an entire city.<\/p>\n\n\n\n
Looking ahead, missions such as the upcoming Compton Spectrometer and Imager (COSI)<\/a> will be able to watch large swaths of the sky with very stable backgrounds, making it easier to catch more ultra-long bursts and study them in detail. <\/p>\n\n\n\n
From collapsing stars to cosmic outliers<\/h2>\n\n\n\n
Up to now, most long gamma ray bursts have been explained by two main scenarios. In the first, a massive, rapidly spinning star collapses into a black hole, launching narrow jets that punch through the dying star and light up the sky. <\/p>\n\n\n\n
In the second, two neutron stars or a neutron star and a black hole spiral together and merge, again driving a short, violent jet.<\/p>\n\n\n\n
Both processes can produce enormous energy, but they are limited by how much material can fall in and how fast. Even in extreme cases, models suggest the engine should shut down after a few thousand seconds. <\/p>\n\n\n\n
GRB 250702B kept going far longer than that, and with sub-second flickers that point to a compact, stellar mass object at its core rather than a supermassive black hole in a galactic center.<\/p>\n\n\n\n
That left astronomers in an interesting spot. The burst looked like it came from a stellar mass black hole, but its duration did not match any standard recipe.<\/p>\n\n\n\n
A black hole falls into a star<\/h2>\n\n\n\n
The new study, led by Eliza Neights of NASA\u2019s Goddard<\/a> Space Flight Center, argues that the best explanation is a so-called helium merger. <\/p>\n\n\n\n In this scenario, a black hole roughly the mass of a star orbits a stripped helium star that has already lost its outer hydrogen layers. As the helium star expands late in its life, the black hole spirals inward, dives into the star\u2019s envelope and begins to tear it apart from within.<\/p>\n\n\n\n When that happens, a huge amount of orbital angular momentum is dumped into the infalling material. Instead of crashing straight into the black hole, the gas forms an extended disc that can feed the central engine for many hours. The result is a long-lived, ultra-relativistic jet that we see as an ultra-long gamma ray burst.<\/p>\n\n\n\n For GRB 250702B, follow up observations in X-ray, infrared and radio light showed an afterglow coming from a dusty, star-forming region in a distant galaxy, well away from its central black hole. The energy in the jet looks fairly normal for a long burst once you account for how narrowly it was focused, but it was spread over a much longer time. <\/p>\n\n\n\n That combination fits naturally with a helium merger, where the total fuel supply is similar to a classic collapsar, just delivered more slowly. It also links this record breaker to other events where gamma ray bursts and unusual supernovae seem to go hand in hand.<\/p>\n\n\n\n If helium mergers are possible, why have we not seen more of these ultra-long bursts? One reason is simple observing bias. Most gamma ray monitors in space are designed to spot short, sharp flashes that stand out clearly above background noise. <\/p>\n\n\n\n Ultra-long bursts are fainter at any given moment and can be interrupted by the Earth blocking the view, so they are easy to miss or misclassify.<\/p>\n\n\n\n In this case, scientists had help from a network of instruments, including the Konus Wind experiment far from Earth, X ray scanners like MAXI on the International Space Station, and even the Psyche spacecraft\u2019s gamma ray and neutron detector, which happened to be in the right place to see part of the event. <\/p>\n\n\n\n Putting all those pieces together was a bit like reconstructing a very long, very glitchy power outage from security cameras across an entire city.<\/p>\n\n\n\n Looking ahead, missions such as the upcoming Compton Spectrometer and Imager (COSI)<\/a> will be able to watch large swaths of the sky with very stable backgrounds, making it easier to catch more ultra-long bursts and study them in detail. <\/p>\n\n\n\nRead More: Astronomers confirm for the first time the existence of a giant volcanic cave on Venus<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
Why we are only seeing these giants now<\/h2>\n\n\n\n