Latest news with #astrophysics
News.com.au
2 hours ago
- General
- News.com.au
‘Coin flip': 50-50 chance Milky Way will be destroyed in collision with Andromeda galaxy
The Milky Way may not have a catastrophic collision with another huge galaxy as has been predicted, computer simulations revealed Monday, giving our home galaxy a coin-flip chance of avoiding destruction. But don't worry either way: no galactic smash-up is expected for billions of years, long after our ageing Sun will have burnt away all life on Earth. The Milky Way and the even-larger galaxy Andromeda are speeding towards each other at 100 kilometres (60 miles) a second, and scientists have long predicted they will collide in around 4.5 billion years. That would be bad news for our neighbourhood. Previous research has suggested that the Sun — and our Earth — could wind up in the centre of this newly merged 'Milkomeda' galaxy and get sucked into its supermassive black hole. Alternatively, the Sun could be shot out into the emptiness of intergalactic space. However 'proclamations of the impending demise of our galaxy seem greatly exaggerated', according to a new study in the journal Nature Astronomy. There is only a roughly 50 per cent chance the Milky Way and Andromeda will smash into each other in the next 10 billion years, the international team of astrophysicists determined. 'It's basically a coin flip,' lead study author Till Sawala of the University of Helsinki told AFP. The researchers ran more than 100,000 computer simulations of our universe's future, using new observations from space telescopes. A galaxy merger in the next five billion years is 'extremely unlikely', Sawala said. Much more likely is that the galaxies will zoom relatively close to each other — say, a little under 500,000 light years away. In only half of the simulations did dark matter then eventually drag the two galaxies together into a cataclysmic embrace. But this would likely only occur in around eight billion years — long after our Sun has died, the researchers found. 'So it could be that our galaxy will end up destroyed,' Sawala said. 'But it's also possible that our galaxy and Andromeda will orbit one another for tens of billions of years — we just don't know.' 'The fate of our galaxy is still completely open,' the study summarised. The researchers emphasised that their findings did not mean that previous calculations were incorrect, just that they had used newer observations and taken into account the effect of more satellite galaxies. Future data releases from Europe's recently retired Gaia space telescope as well as Hubble could provide a definitive answer to this question within the next decade, Sawala predicted. How much all this all matters to us is a matter of debate. The Sun is expected to make Earth inhospitable to life in around a billion years. 'We might have some emotional attachment' to what happens after we're gone, Sawala said. 'I might prefer the Milky Way not to collide with Andromeda, even though it has absolutely no relevance to my own life — or the lives of my children or great-great grandchildren.'
News.com.au
10 hours ago
- General
- News.com.au
Milky Way may not be destroyed in galactic smash-up after all
The Milky Way may not have a catastrophic collision with another huge galaxy as has been predicted, computer simulations revealed Monday, giving our home galaxy a coin-flip chance of avoiding destruction. But don't worry either way: no galactic smash-up is expected for billions of years, long after our ageing Sun will have burnt away all life on Earth. The Milky Way and the even-larger galaxy Andromeda are speeding towards each other at 100 kilometres (60 miles) a second, and scientists have long predicted they will collide in around 4.5 billion years. That would be bad news for our neighbourhood. Previous research has suggested that the Sun -- and our Earth -- could wind up in the centre of this newly merged "Milkomeda" galaxy and get sucked into its supermassive black hole. Alternatively, the Sun could be shot out into the emptiness of intergalactic space. However "proclamations of the impending demise of our galaxy seem greatly exaggerated", according to a new study in the journal Nature Astronomy. There is only a roughly 50 percent chance the Milky Way and Andromeda will smash into each other in the next 10 billion years, the international team of astrophysicists determined. "It's basically a coin flip," lead study author Till Sawala of the University of Helsinki told AFP. The researchers ran more than 100,000 computer simulations of our universe's future, using new observations from space telescopes. A galaxy merger in the next five billion years is "extremely unlikely", Sawala said. Much more likely is that the galaxies will zoom relatively close to each other -- say, a little under 500,000 light years away. In only half of the simulations did dark matter then eventually drag the two galaxies together into a cataclysmic embrace. But this would likely only occur in around eight billion years -- long after our Sun has died, the researchers found. "So it could be that our galaxy will end up destroyed," Sawala said. "But it's also possible that our galaxy and Andromeda will orbit one another for tens of billions of years -- we just don't know." - Galaxy's fate 'open' - "The fate of our galaxy is still completely open," the study summarised. The researchers emphasised that their findings did not mean that previous calculations were incorrect, just that they had used newer observations and taken into account the effect of more satellite galaxies. Future data releases from Europe's recently retired Gaia space telescope as well as Hubble could provide a definitive answer to this question within the next decade, Sawala predicted. How much all this all matters to us is a matter of debate. The Sun is expected to make Earth inhospitable to life in around a billion years. "We might have some emotional attachment" to what happens after we're gone, Sawala said. "I might prefer the Milky Way not to collide with Andromeda, even though it has absolutely no relevance to my own life -- or the lives of my children or great-great grandchildren." dl/jxb
Yahoo
3 days ago
- General
- Yahoo
The Universe's Most Powerful Cosmic Rays May Finally Be Explained
Somewhere in our galaxy are engines capable of driving atomic fragments to velocities that come within a whisker of lightspeed. The explosive deaths of stars seems like a natural place to search for sources of these highly energetic cosmic bullets, yet when it comes to the most powerful particles, researchers have had their doubts. Numerical simulations by a small international team of physicists may yet save the supernova theory of cosmic ray emissions at the highest of energies, suggesting there is a brief period where a collapsing star could still become the Universe's most extreme accelerator. For more than a century, scientists have scanned the skies for phenomena that may be responsible for the relatively constant showers of atomic nuclei and occasional electrons that pepper our planet. Simply following their trajectory would be like picking up a bottle on the beach and looking to the horizon for its home. The charges of most cosmic rays put them at the mercy of a turbulent ocean of magnetic fields across the galaxy and beyond, leaving researchers to search for other clues. A mere few thousand light years away in our galactic backyard, the historic supernova known as Tycho's star has been studied for signs of physics capable of accelerating charged particles. In 1572, astronomers marveled at the star's sudden brightening, now understood to be the final hoorah of a white dwarf ending its life in a thermonuclear catastrophe. As its core collapsed under its own weight, the burst of heat and radiation slammed into the shell of surrounding gases, generating immense magnetic fields. In 2023 researchers published their analysis on those fields, finding their ability to generate cosmic rays was "significantly smaller" than those expected of existing models. While this doesn't rule out collapsing stars as potential particle accelerators, it does raise questions on just how much power they can provide. Every now and then, Earth is struck by some true monsters – particles that are up to a thousand times more powerful than anything our own technology has been capable of generating. These peta-electronvolt (PeV) energies are the work of hypothetical cosmic engines dubbed PeVatrons. According to astrophysicists Robert Brose from the University of Potsdam in Germany, Iurii Sushch from the Spanish Centre for Energy, Environmental and Technological Research, and Jonathan Mackey from the Dublin Institute for Advanced Studies, dying stars just might be the mysterious PeVatrons scientists have been searching for. For it to work, the dying star first needs to cough up enough material to form a dense shell around itself. Then, at the moment of supernova the rapidly expanding shock wave smashes into this dense environment, generating the necessary magnetic turbulence to whip nuclei and electrons towards PeV-levels of acceleration. The critical element, they claim, is timing – only within its first decade or two is the surrounding shell dense enough to provide the amount of turbulence required for particles to reach the highest of energies. "It is possible that only very young supernova remnants evolving in dense environments may satisfy the necessary conditions to accelerate particles to PeV energies," the team writes. Had Tycho's star held its breath for just another few centuries, astrophysicists may have recorded a shower of cosmic rays at the highest of magnitudes. Perhaps in the near future, the violent end of another nearby star just might give us the opportunity they need to solve the perplexing mystery of PeVatrons once and for all. This research has been accepted for publication in Astronomy & Astrophysics. China's Tianwen-2 Launches to Grab First 'Living Fossil' Asteroid Samples Scientists Have Clear Evidence of Martian Atmosphere 'Sputtering' Chance X-Ray Discovery Reveals Mystery Object 15,000 Light Years Away
Forbes
4 days ago
- General
- Forbes
Astronomers Need Better Models To Explain Webb's Puzzling Observations
Thousands of galaxies flood this near-infrared image of galaxy cluster SMACS 0723. In one fell swoop, NASA's James Webb Space Telescope has largely revolutionized much of what astronomers know about the formation and assembly of the earliest galaxies in the cosmos. Webb has not only pushed back the tape of galaxy formation, but even mainstream observational astronomers now realize that their models need updating to explain what Webb has been seeing only 300 million years after the big bang. To answer the question of how mass assembles in the early Universe and how galaxies are forming their stars, it's clear that the models we've developed for the nearby Universe need to be updated for the distant universe, Alex Cameron, a postdoctoral researcher in astrophysics at the University of Oxford, tells me in his office. The physics of how stars form, how they evolve, is very complex, and there are big uncertainties in our models, says Cameron. So, before we start questioning the age of the universe and how old these galaxies must be, we need to do a lot of work to better calibrate our understanding of the stars themselves, says Cameron. The success we have had in shattering records for the most distant galaxies implies that galaxy formation got underway very early in the history of the universe, Andy Bunker, professor of Astrophysics at the University of Oxford, told me via email. The fact that we see the fingerprints of heavy elements such as carbon and oxygen in the most distant galaxies implies that previous generations of stars have already formed, and that 'first light' in the universe happened even earlier, he says. Bright galaxies appear to be ubiquitous in the early cosmos. Everywhere we look, we're finding a lot of bright galaxies, says Cameron. The challenge is to disentangle whether these galaxies are bright because they've got a lot of stars in them or whether they're bright, because the stars that have formed are brighter than typical present-day stars, he says. The signatures that we're getting from these observations tell us that there's a lot that we don't understand about the properties of these very early stars, says Cameron. In less than three years, Webb's sensitivity to galaxy formation is arguably more than in the past twenty years with Hubble and large ground-based telescopes, Richard Ellis, professor of astrophysics at University College London, tells me via email. Webb has revealed that some galaxies at the earliest epochs are very bright in the ultraviolet, which is telling us something about how stars form vigorously in these early galaxies, says Bunker. What's most puzzling about these early galaxies? The standard picture posits that galaxies assemble their stars gradually over time via infalling gas and mergers, says Ellis. Yet, the earliest galaxies are often more luminous than ones seen later, he says. The relative abundances of some chemical elements at these high redshifts are also unusual with astronomers particularly puzzled by why galaxies at such early times are so rich in the element of nitrogen. But are we in sight of the cosmological holy grail? I think we are observing these systems at a special time, perhaps close to the moment of their birth, says Ellis. They could be unusually luminous because they may be bursting into life a few tens of millions of years after formation; in this case they would not be able to sustain this luminosity for very long, he says. Yet they may also simply have more massive stars than those seen in galaxies at later times. Either way, it's pointing to the fact we may be getting close to a 'holy grail' when galaxies first emerged from darkness, says Ellis. It may not be possible to find a 'chemically pristine' galaxy first emerging from darkness, says Ellis. That's because the five-to-ten-million-year window in time when this gas had such a primordial composition was so short. But when the gas is first heated by young stars it will induce an absorption signal in the cold gas seen against the glow of the big bang, says Ellis. The Square Kilometer Array (a massive international radio telescope project) nearing completion in Western Australia has the potential to see this clinching signal in concert with further progress with Webb, he says.
Yahoo
24-05-2025
- Science
- Yahoo
Pluto's 'extreme cousin' is a dwarf planet found at the far reaches of our solar system
Earth has a newly-discovered neighbor in the solar system. But the heavenly body – possibly a dwarf planet à la Pluto – isn't a frequent visitor. Located beyond Neptune, its extreme orbit circumnavigates the sun once every 25,000 years, taking it beyond our solar system. The new object, named 2017 OF201, was discovered by researchers in an astronomical image database while searching for trans-Neptunian objects (TNOs) and possible new planets in the outer solar system. Sihao Cheng, an astrophysicist at the Institute for Advanced Study's School of Natural Sciences, led the team that discovered the object, which he described as an "extreme 'cousin' of Pluto," in a comment on his personal website. 2017 OF201 is about one-third the size of Pluto, which was reclassified as a dwarf planet in August 2006, and "is likely large enough to qualify as a dwarf planet, and its orbit is extremely wide," Cheng said. Jupiter: Our solar system's biggest planet used to be twice as large: Study 'The object's aphelion – the farthest point on the orbit from the Sun – is more than 1600 times that of the Earth's orbit,' Cheng said in a synopsis of the findings posted May 22 on the Institute for Advanced Study (IAS) website. "Meanwhile, its perihelion – the closest point on its orbit to the Sun – is 44.5 times that of the Earth's orbit, similar to Pluto's orbit." The researchers identified 2017 OF201 using 19 different astronomical database exposures, captured over seven years. The International Astronomical Union's Minor Planet Center officially announced the new object's discovery on May 21, the IAS said. 2017 OF201's extreme orbit makes it detectable about 1% of the time, the researchers said. Spotting 2017 OF201 beyond the Kuiper Belt, a donut-shaped section of space past the orbit of Neptune filled with icy debris, suggests the region may not be as empty as previously thought. "The presence of this single object suggests that there could be another hundred or so other objects with similar orbit and size; they are just too far away to be detectable now,' Cheng said in the synopsis. 'Even though advances in telescopes have enabled us to explore distant parts of the universe, there is still a great deal to discover about our own solar system.' The extreme orbit of 2017 OF201 also suggests the object "must have experienced close encounters with a giant planet, causing it to be ejected to a wide orbit,' said Eritas Yang, a Princeton University graduate student who assisted in the research, in the study synopsis. More than one galactic event could have created 2017 OF201's orbit, Cheng added. "It's possible that this object was first ejected to the Oort cloud, the most distant region in our solar system, which is home to many comets, and then sent back," he said. The new object could also challenge the hypothesis that there's a "Planet X" or "Planet Nine" beyond Pluto, with gravity affecting dwarf planets and other objects in the Kuiper Belt. That's because 2017 OF201's orbit is "well outside the clustering observed in extreme (TNOs), which has been proposed as dynamical evidence for a distant, undetected planet," the researchers write in a draft version of their submitted research. "The existence of 2017 OF201 might suggest that Planet 9 or X doesn't exist," said Jiaxuan Li, another Princeton University astrophysical sciences grad student who collaborated on the research, on his personal website. But research will continue. "I hope Planet 9 still exists, because that'll be more interesting," Cheng told the New Scientist. Contributing: Doyle Rice and Elizabeth Weise. Mike Snider is a reporter on USA TODAY's Trending team. You can follow him on Threads, Bluesky, X and email him at mikegsnider & @ & @mikesnider & msnider@ What's everyone talking about? Sign up for our trending newsletter to get the latest news of the day This article originally appeared on USA TODAY: Space oddity: New 'dwarf planet' found beyond Neptune
