Stellar Catastrophes: The Most Powerful Explosions Since the Big Bang

[00:00:00] This is SpaceTime Series 28 Episode 70, full broadcast on the 11th of June 2025. Coming up on SpaceTime, the biggest explosion since the Big Bang, NASA's Perseverance Mars rover takes a bite out of one of the oldest rocks on the Red Planet, and first light for Europe's new killer asteroid hunter. All that and more coming up on SpaceTime. Welcome to SpaceTime with Stuart Gary.

[00:00:43] Astronomers have discovered what they now believe are the most powerful cosmic explosions since the Big Bang. These blasts so enormous, they've been categorized as a new class of event, which are being called Extreme Nuclear Transients or ENTs. These extraordinary phenomena recorded in the Journal of Science Advances occur when stars at least three times more massive than our Sun are quite literally torn apart by supermassive black holes in what are known as gravitational tidal disruption events.

[00:01:12] Their destruction releases vast amounts of energy visible across enormous distances. The study's lead author, Jason Hinkle from the University of Hawaii, says astronomers have observed stars getting ripped apart in tidal disruption events for over a decade. But these Extreme Nuclear Transients are a very different beast, reaching brightnesses nearly ten times greater than what are typically seen. Hinkle says not only are Extreme Nuclear Transients far brighter than normal tidal disruption events, but they remain luminous for years,

[00:01:42] far surpassing the energy output of even the brightest known supernova explosions. He says the immense luminosities and energies of these Extreme Nuclear Transients are truly unprecedented. For example, the most energetic of these so far studied, named Gaia 18 CDJ, emitted an astonishingly 25 times more energy than the most powerful supernovae ever seen. Now, a typical supernova would release as much energy in a year as our Sun will in its entire 12 billion year lifespan.

[00:02:11] By comparison, Extreme Nuclear Transients are radiating the energy of a hundred suns over a single year. Extreme Nuclear Transients were first uncovered when Hinkle began a systematic search of public transient surveys, looking for long-lived flares being emitted from the centres of galaxies. Eventually, he identified two unusual flares in data from the European Space Agency's Gaia mission. These flares brightened over timescales far longer than known transients,

[00:02:39] and without the sorts of characteristics common to these events. Now, Hinkle points out that Gaia doesn't tell you what a transient is, just that something has changed in brightness. But when he saw these smooth long-lived flares from the centres of distant galaxies, he knew he was looking at something unusual. And so that discovery launched a multi-year follow-up campaign, trying to figure out exactly what these sources were. Using a number of telescopes, including the giant 10-metre Keck twins in Hawaii, Hinkle and colleagues gathered data across the electromagnetic spectrum.

[00:03:09] And recently, a third event with similar properties to the other two was discovered by the Zwicky Transient Facility, further supporting the idea that extreme nuclear transients are a different and new class of extreme astrophysical events. Now, the authors determined that these extraordinary events couldn't be regular supernovae, because they released far more energy than any known stellar explosion. The sheer energy budget, combined with their smooth and prolonged light curves, clearly pointed to an alternative mechanism, accretion onto a supermassive black hole.

[00:03:38] However, extreme nuclear transients differ significantly from normal black hole accretion, which typically shows irregular and unpredictable changes in brightness. The smooth and long-lived flares of extreme nuclear transients indicates a distinct physical process, the gradual accretion of a disrupted star by a supermassive black hole. And now their fortuitous discovery will provide a valuable new tool for studying massive black holes in distant galaxies.

[00:04:05] See, because they're so bright, astronomers can see them across vast cosmic distances. And of course, in astronomy, looking further away means you're looking further back in space-time. So, by observing these prolonged flares, astronomers will gain new insights into black hole growth from a time when the universe was just half its current age, a time when stars were forming and feeding their supermassive black holes at a rate 10 times more vigorously than what's happening today. But the rarity of extreme nuclear transients,

[00:04:34] occurring at least 10 million times less frequently than supernovae, makes their detection challenging and dependent on the sustained monitoring of the cosmos. Still, Hinkle says these extreme nuclear transients don't just mark the dramatic end of a massive star's life, they illuminate the very processes responsible for growing the largest black holes in the universe. And that is spectacular. This is space-time. Still to come, NASA's Mars Perseverance rover takes a bite out of one of the oldest rocks on the red planet.

[00:05:05] And the European Space Agency's newest planetary defender opens its eyes for the first time. All that and more still to come, on Space Time. NASA's Mars Perseverance rover has taken a bite out of what could be one of the oldest rocks on the red planet.

[00:05:34] The six-wheeled car-sized robotic laboratory is exploring a new area on the red planet known as Crocodile, located on the lower slope of the Jezero Crater Rim. Crocodile was on the Perseverance science team's wish list because it marks an important boundary between the oldest rocks on Jezero Crater's rim and the rocks of the Martian plains beyond the crater. Perseverance deputy project scientist Ken Farley from Caltech says the last five months have been a geologic whirlwind,

[00:06:01] with Crocodile promising to be just as compelling as the recent exploration of Witch Hazel Hill. Named by Perseverance mission scientists after a mountain ridge in Fiordland, Norway, Crocodile is a 30-hectare plateau of rocky outcrops located downslope and to the west and south of Witch Hazel Hill. A quick earlier investigation of the region revealed the presence of clays in ancient bedrock. Now because clays require liquid water to form, they provide important clues about the environment and habitability of early Mars.

[00:06:31] The detection of clays elsewhere within the Crocodile region will thereby reinforce the idea that abundant liquid water was present sometime in early Martian history, likely long before Jezero Crater itself was formed by the impact of an asteroid. Now here on Earth, clay minerals are known for preserving organic compounds, the building blocks of life. Farley says if they find potential biosignatures on Crocodile, it would most likely have formed from an entirely different and much earlier epoch of Mars evolution

[00:07:00] than the samples found last year in Cheever Falls, which was the location of a rock sampled back in July 2024, which had chemical signatures and structures which could have been formed by life long ago. The Crocodile rocks formed long before Jezero Crater was created, during Mars' earliest geologic period known as the Nocheon, and thereby they're among the oldest rocks known on Mars. Data collected by orbiting NASA spacecraft suggest that the outer edges of Crocodile may also have areas rich in olivine and carbonate.

[00:07:30] Now while olivine forms from magma, carbonate materials, at least here on Earth, typically form during reaction with liquid water, between rocks and dissolved carbon dioxide. And carbonate minerals on Earth are known to be excellent preservers of fossilised ancient microbial life, as well as being good recorders of ancient climate. The Perseverance rover has just celebrated its 1500th day of surface operations on the Red Planet,

[00:07:55] and is currently analysing a rocky outcrop in Crocodile called Copper Cove, which may contain Nocheon rocks. The rover's arrival at Crocodile also comes with a new sampling strategy, one that allows for leaving some caught samples unsealed, just in case the mission finds more scientifically compelling geological features down the road. See, so far, Perseverance has collected and sealed two regular samples, three witness tubes, and one atmospheric sample in the area.

[00:08:21] It's also collected a further 26 rock cores and sealed 25 of them. The rover's one unsealed sample is the most recent, a rock core sample taken on April 28th at the team of name Bell Island, and which contains small round stones called spherals. Now if at some point the science team decides that the new sample should take its place, the rover will simply be commanded to remove the tube from its cache and dump the previous content. See, the thing is, there are just seven empty sample tubes remaining on the rover,

[00:08:51] and there's lots more Mars yet to explore. This is space-time. Still to come. First light for Europe's new killer asteroid hunter. And later in the science report, a new study has found that global drought severity has increased by an average of 40% since 1981. All that and more still to come on Space Time.

[00:09:28] The European Space Agency's newest planetary defender has opened its eyes to the skies for the first time. The FlyEye telescope's first light marks the beginning of a new chapter in how astronomers scan the skies, searching for near-Earth asteroids and comets which could pose a threat to our planet. FlyEye is inspired by the insect's compound eye, designed to capture a region of the sky more than 200 times as large as the full moon in a single exposure. Much larger than a conventional telescope.

[00:09:57] It will use this wide field of view to automatically survey the night skies independent of human operation, and its computer systems will allow it to identify any new asteroids which could pose a threat to Earth. FlyEye project manager Ernesto Derling says a network of up to four FlyEye telescopes spread across the northern and southern hemisphere will work together to further improve the speed and completeness of these automatic sky surveys, and to reduce their dependence on good weather at any individual site.

[00:10:26] See, the earlier astronomers can spot potentially hazardous asteroids, the more time they'll have to assess them and, if necessary, prepare a response. ESA's Near-Earth Asteroid Coordination Centre will then verify any potential new asteroid detections made by FlyEye and submit those findings to the Minor Planet Centre, Earth's hub for asteroid observational data. Astronomers will then carry out follow-up observations to further assess the hazard that the object may pose to our planet.

[00:10:52] FlyEye is equipped with a one-metre primary mirror, which efficiently captures incoming light. The light's then divided into 16 separate channels, each equipped with a camera capable of detecting very faint objects. It's this which enables simultaneous high-sensitivity operations over a large region of the sky at once. During operations, FlyEye's observation schedule will be optimised to consider factors such as the Moon's brightness and the work of other survey telescopes, such as the NASA-funded Atlas Project,

[00:11:22] the ZVICI Transient Facility and the upcoming Vera Rubin Telescope. This report from ESA TV. Hi, I'm Kelsey Brennan-Wessels for ESA Web TV. We join you from Milan, Italy at OHB Italia, where a new high-tech telescope to detect asteroids is being built. Traditional telescopes have a narrow field of view, which makes hunting for threatening asteroids a slow and tedious process.

[00:11:46] But the FlyEye has 16 individual cameras mimicking the structure of a fly's compound eye to offer an extra-wide field of view of 44 square degrees. With this field of view, the telescope will be able to detect asteroids at risk of hitting Earth in as little as a week in advance. So, how does it work? Lorenzo Cibin at OHB Italia gave us an up-close look at the machinery.

[00:12:12] The full optical instrument connected to the ground support equipment. Such a lower part is the primary mirror. There is a beam shaper that do a repartition of the field in 16 channels. For example, one channel with a CCD camera. And this CCD projected portion of the sky. An additional three telescopes are foreseen to be produced and placed in complementary locations around the globe,

[00:12:40] to increase coverage and improve the efficiency of the network. This first fly-eye telescope is destined for Mount Mufara on the Italian island of Sicily. The telescope has to be mounted, has to be associated to an equatorial mount. Equatorial mount is a particular mount that allows to avoid that during the exposure time, the stars track. And the stars in this way remain fixed in their position when we take a picture from the telescope.

[00:13:09] And while the telescope is taking its pictures, it's important that the structure is very stiff in order to reduce vibrations that could blur the image, and thus reduce the capability to detect very faint objects in the night sky. And in that report from ESA TV, we heard from FlyEye project manager Lorenzo Cibin and senior optical engineer Marco Ciarini, both from OHB Italia. And this is Space Time.

[00:13:39] And time now to take another brief look at some of the other stories making news in science this week, with a science report. A new study has found that global drought severity has increased by an average of 40% since 1981.

[00:14:08] The findings reported in the journal Nature, famed the likely driver is the process called atmospheric evaporative demand. The authors developed a database of global droughts from 1901 to 2022. They found an increasing trend in drought severity around the world, with drier areas becoming drier and wetter areas also experiencing drying trends. Interestingly, they found that the drought trends tend to remain largely flat until 1981. That was the turning point.

[00:14:37] The findings suggest that atmospheric evaporative demand plays a large role in increasing drought severity. And it's likely to continue under future warming scenarios. A new study has found that men who carry a common genetic variant are twice as likely to develop dementia as women. The findings reported in the journal Neurology are based on data from the Asprey trial, which was investigating people who had variants of the hemochromatosis HFE gene.

[00:15:05] This gene is critical for regulating iron levels in the body and may also be associated with an increased risk of dementia. The act of yawning is contagious in many mammals. When you see someone yawn, chances are you'll yawn as well. Now a new study published in the journal Scientific Reports has found that even chimpanzees can also catch yawns, not just from other chimpanzees or people, but even from human-like robots.

[00:15:33] The study's authors showed 14 chimpanzees a robot that can make human facial expressions, including yawning, and they observed that the chimps would respond in kind. They say eight of the chimpanzees yawned in response to the robotic yawning, and that the chimps then even lay down in response to the yawn, with some gathering bedding for a rest. The authors say this is likely the first study to show contagious yawning in response to a robot, and it could mean that chimpanzees see yawning as the cue to have a rest.

[00:16:03] Nintendo have finally launched their long-awaited Switch 2 gaming console. First announced back in January, it's the first major console launch in five years. The last was back in 2020 when Sony's PlayStation 5 hit the shelves. With the details, we're joined by technology editor Alex Harov-Reut from TechAdvice.Life. The Nintendo Switch 2, we've been talking about it for quite some time. It's the second generation of Nintendo's ultra-popular handheld gaming machine.

[00:16:29] I mean, children of the 80s like myself and many people listening will remember the Game & Watch series from Nintendo with Donkey Kong and Oil Panic and a bunch of other games that were like a very primitive version of the Nintendo 3DS, the games console that flipped open. The Nintendo Switch, now the Switch 2, gives you a giant screen and removable controls. You can connect that screen to a dock to your TV and have a full-on gaming console experience. And of course, from Nintendo in fierce competition with Microsoft, Xbox, and Sony's PlayStation 5.

[00:16:59] So the new model is $699 for the console by itself with the controllers and the dock and charging, and $769 with the Mario Kart World bundle, which of course is the launch game. I mean, the Game Boy had Tetris and there's also a Red Bull Tetris. There's a stack of game reviews you can look at online and experiences from different people. But it's the handheld console to beat and very quickly there's Windows handheld consoles, there's the Steam Deck, and there's a lot of competition in the space. But Nintendo has been doing this for decades, and this is their best handheld gaming device yet.

[00:17:28] That's Alex Harrovoit from techadvice.life. And that's the show for now. Space Time is available every Monday, Wednesday, and Friday through Apple Podcasts,

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