Latest news with #radioastronomy
Yahoo
6 days ago
- Science
- Yahoo
Fast internet is getting in the way of understanding the universe, scientists warn
The rush for faster and more widely available internet is making it harder to understand the cosmos, according to scientists. SpaceX's Starlink satellites are intended to circle the Earth and offer fast internet in regions that might otherwise be underserved. The company has launched thousands of them in recent years, with a view to covering the planet with signals. But researchers have found that the satellites are interfering with radio astronomy, getting in the way of astronomers' view of space. The satellites leak out unintended signals that drown out the often very faint radio waves that astronomers use to see the universe. The new work from Curtin University looked specifically at SpaceX's Starlink because it has the most satellites in orbit. But a number of other companies are looking to use satellites to offer faster and more widely available internet. In the research, scientists gathered 76 million images of the sky using an early version of the Square Kilometre Array, which will be the world's biggest and most sensitive radio telescope when it is finished later this decade. In that data, scientists found more than 112,000 radio emissions from 1,806 Starlink satellites. Those emissions could make it much more difficult for scientists to see the important radio signals that they rely on. 'Starlink is the most immediate and frequent source of potential interference for radio astronomy: it launched 477 satellites during this study's four-month data collection period alone,' said Dylan Grigg, who led the study. 'In some datasets, we found up to 30 per cent of our images showed interference from a Starlink satellite.' Many of those signals were not being intentionally emitted from the satellites, and come more strongly at different frequencies than expected. That could make it difficult for researchers to pick them out. 'Some satellites were detected emitting in bands where no signals are supposed to be present at all, such as the 703 satellites we identified at 150.8 MHz, which is meant to be protected for radio astronomy,' Mr Grigg said. 'Because they may come from components like onboard electronics and they're not part of an intentional signal, astronomers can't easily predict them or filter them out.' That interference could eventually keep us from understanding deep truths of the cosmos, the researchers warned. 'We're standing on the edge of a golden era where the SKA will help answer the biggest questions in science: how the first stars formed, what dark matter is and even test Einstein's theories,' said Steven Tingay, who helped author the study. 'But it needs radio silence to succeed. We recognise the deep benefits of global connectivity but we need balance and that starts with an understanding of the problem, which is the goal of our work.' Error in retrieving data Sign in to access your portfolio Error in retrieving data
The Guardian
6 days ago
- Science
- The Guardian
Sir Francis Graham-Smith obituary
Sir Francis Graham-Smith, who has died aged 102, was the last of the generation that created modern radio astronomy, the branch of astronomy that studies the universe with radio waves, in the 1940s and 50s. His PhD thesis, on the first Cambridge radio survey, carried out between 1948 and 1950, with reasonably accurate positions for the brightest sources, paved the way to demonstrating that the majority of celestial radio sources are distant galaxies with massive black holes in their nuclei. Following the discovery of pulsars, pulsating radio sources associated with rapidly rotating neutron stars, in 1967 by Antony Hewish, Jocelyn Bell and others, Graham-Smith used the Jodrell Bank Mark I telescope to study pulsars in detail. He and Andrew Lyne wrote the definitive book on the subject, Pulsar Astronomy (1990). Graham-Smith's first radio survey was carried out with a pair of captured German Wurzburg radar antennae used as an interferometer, where the differences in the signals from the two antennae are used to construct an image of the sky. There were four really bright sources, named for the constellations they fell in: Cassiopeia A, Taurus A, Cygnus A and Virgo A, and Graham-Smith gave the first accurate positions for these in a 1951 paper in the journal Nature. The importance of these positions for the identification of the powerful radio galaxies Messier 87 and Cygnus A launched his career. However the survey was not an unmitigated success. Most of the rest of the 50 sources listed eventually turned out to be spurious. In addition, in their 1950 survey paper, Martin Ryle, Bruce Elsmore and Graham-Smith, while considering the possibility that the radio sources were extragalactic, opted for the interpretation that they were some kind of active star. By the time of the second survey in 1955, the Cambridge group had changed their minds about this and now believed the sources were mostly extragalactic. This 1955 survey gave extraordinarily steep counts of sources as they looked towards fainter fluxes. Ryle claimed that this proved that we must live in an evolutionary universe, in contradiction to the steady-state theory advocated by Fred Hoyle and others. Unfortunately the survey was also strongly affected by spurious sources generated by the interferometer, and it was only with the third Cambridge survey in 1962 that the correct source-counts were measured. Graham-Smith was involved with the development of the more accurate interferometers used for the second and third surveys, and with the third survey, the revolution initiated by Graham-Smith's 1951 paper on interferometric radio positions could now begin. When the first ever satellite, the Soviet Sputnik, was launched in 1957, Jodrell Bank famously tracked the launch rocket casing, but it was Graham-Smith who used the Cambridge interferometer to track the satellite itself and was able to demonstrate the precession of its orbit due to the Earth's equatorial bulge. In 1964 Graham-Smith moved to a professorship at Jodrell Bank, Manchester, taking with him a new PhD student, Andrew Lyne, who was to be his key collaborator for the next 40 years. This turned out to be a very fortuitous move, because three years later Antony Hewish and Jocelyn Bell discovered pulsars at Cambridge. However the ideal telescope for detailed study of pulsars was the 250ft Mark I telescope at Jodrell Bank, and Graham-Smith, Lyne and the Jodrell team threw themselves into this work, becoming world-leading experts in this field. They worked on the relativistic beam ('lighthouse') model of the pulses, monitoring the long-term slowing-down of the rotation speeds of the neutron stars. In 1971 the Jodrell Bank Mark I telescope was given a new surface so that it could operate at higher frequencies, and Graham-Smith procured a laser device to map its shape. Lyne said: 'He was able to tell the engineers the number of turns required on each of the several hundred adjusting nuts in the backing structure to perfect its shape. This was the radio-astronomer's equivalent of polishing the mirror of an optical telescope and gave us a wonderful radio instrument. It was a spectacular feat of measurement at that time.' Graham-Smith was born in London, the son of Claud Smith, a civil servant, and Cicely (nee Kingston). In early scientific papers he was FG Smith and hyphenated his name only after being knighted in 1986. He attended Epsom college and Rossall school in Fleetwood, Lancashire, and then went to Downing College, Cambridge, in 1941, to study natural sciences. In 1943 he was seconded to work on radar at the Telecommunications Research Establishment at Malvern, returning to complete his degree in 1946. He began a PhD in Ryle's radio astronomy group, working at first with simple dipole antennae to study the size of solar flares, and then with increasingly complex radio interferometers to measure the positions of radio sources, culminating in the first Cambridge Radio Catalogue in 1950 and the accurate positions of the four brightest radio sources in the sky in 1951. The dominance of radio astronomy on the British astronomical scene in the 1960s and 70s was reflected in Graham-Smith's appointment in 1975 as director of the Royal Greenwich Observatory at Herstmonceux, East Sussex. During his tenure he oversaw the development of the UK observatory on La Palma in the Canary Islands, the shipment of the 2.4m Isaac Newton Telescope to La Palma in 1979, and the plans for what became the 4.2m William Herschel Telescope, which eventually saw first light in 1987. In 1981, on the death of Sir Bernard Lovell, Graham-Smith moved back to Manchester to become director of Jodrell Bank, in which post he continued till his retirement in 1988. He secured funding for a major upgrade of the Merlin interferometric array, including the construction of the 32m telescope at Cambridge. These endeavours set the scene for Jodrell Bank to play a leading national role in the future international Square Kilometre Array (SKA) telescope, which is now being built in Australia, but has its headquarters at Jodrell Bank. Graham-Smith delivered the 1965 Royal Institution Christmas Lecture jointly with Lovell, Ryle and Hewish. He was made a fellow of the Royal Society in 1970 and was awarded the society's Royal Medal in 1987. From 1975 to 1977, he was president of the Royal Astronomical Society and, from 1982 to 1990, he was Astronomer Royal, following Ryle in the post. In 1986 he was unlucky enough to be involved in a live television broadcast of the flypast of Halley's comet by the European Space Agency's Giotto mission, during which none of the astronomers present could work out what was happening with the images. This broadcast was said to have angered Margaret Thatcher and resulted in cuts to UK space science funding. Graham-Smith was the author of several books, including Pulsar Astronomy, which went through five editions, and Introduction to Radio Astronomy (1997), with Bernie Burke, which went through four editions. He was still writing highly cited papers in his 90s. Throughout his life Graham-Smith was a keen gardener, and for many years an avid bee-keeper. He was looked after by his daughter, Helen, in his last few years. His wife, Elizabeth (nee Palmer), whom he married in 1945, died in 2021. He is survived by Helen and three sons. Francis Graham-Smith, astronomer, born 25 April 1923; died 20 June 2025
Yahoo
19-07-2025
- Science
- Yahoo
Newly discovered 'cosmic unicorn' is a spinning dead star that defies physics: 'We have a real mystery on our hands'
When you buy through links on our articles, Future and its syndication partners may earn a commission. Using the world's most advanced radio telescopes, astronomers have discovered a spinning dead star so rare, strange and unique that they have dubbed it a "cosmic unicorn." The unique properties of this object, CHIME J1634+44, challenge our current understanding of spinning dead stars and their environments. CHIME J1634+44, also known as ILT J163430+445010 (J1634+44), is part of a class of objects called Long Period Radio Transients (LPTs). LPTs are a newly found and mysterious type of celestial body that emits bursts of radio waves that repeat on timescales of minutes to hours. That's significantly longer than the emission of standard pulsars, or rapidly spinning neutron star stellar remains that sweep beams of radiation across the cosmos as they spin. But as strange as all LPTs are, CHIME J1634+44 still stands out. Not only is it the brightest LPT ever seen, but it is also the most polarized. Additionally, its pulses of radiation seem highly choreographed. And what really stands out about CHIME J1634+44 is the fact that it is the only LPT astronomers have ever seen whose spin is speeding up. "You could call CHIME J1634+44 a 'unicorn' even among other LPTs. The bursts seem to repeat either every 14 minutes or 841 seconds — but there is a distinct secondary period of 4206 seconds, or 70 minutes, which is exactly five times longer," team leader Fengqiu Adam Dong, a Jansky Fellow at the Green Bank Observatory (GBO), said in a statement. "We think both are real, and this is likely a system with something orbiting a neutron star." The team discovered the unusual traits of CHIME J1634+44 using ground-based instruments including the Green Bank Telescope, the Very Large Array (VLA), the Canadian Hydrogen Intensity Mapping Experiment (CHIME) Fast Radio Burst and Pulsar Project, the NASA-operated space-based observatory, and the Neil Gehrels Swift Observatory (Swift). The object was, in fact, simultaneously discovered by a separate team of astronomers at ASTRON, the Netherlands Institute for Radio Astronomy, using the LOFAR (Low Frequency Array) radio telescope. While the team led by Dong believes a stellar remnant at the heart of CHIME J1634+44 is a neutron star, the ASTRON team, captained by astronomer Sanne Bloot, refers to it as J1634+44 and think it is a white dwarf. What both teams agree on, though, is just how strange this LPT is. This unicorn is speeding up by feeding on a star Both white dwarfs and neutron stars are dead stars created when stars of differing masses run out of the fuel supplies they need for nuclear fusion at their cores. Once that fuel is over, the stars can no longer support themselves against their own immense gravities. Neutron stars are stellar remnants that form when massive stars, with masses at least eight times that of the sun, reach the end of their lives and collapse. Smaller stars closer in mass to the sun leave behind a slightly less extreme stellar remnant called a "white dwarf." Though most of the mass of these dying massive stars is shed in supernova explosions, the cores of the stars maintain a mass between one and two times that of the sun. This is crushed down to a width of around 12 miles (20 kilometers), creating matter so dense that if a teaspoon of neutron star "stuff" were scooped out and brought to Earth, it would weigh 10 million tons (equal to stacking 85,000 blue whales on a teaspoon). This collapse has another extreme consequence. The dying star maintains its angular momentum, meaning that when its radius is rapidly reduced during collapse, it speeds up greatly. Though the collapse of white dwarfs is less extreme, it also causes an increase in spin speed due to the conservation of angular momentum. An Earth-based example of this is an ice skater pulling in their arms to increase the speed of their spin. What this means is some young neutron stars can spin as fast as 700 times every second. However, as neutron stars and white dwarfs age, they should slow down as they lose energy. That's why no matter what CHIME J1634+44 is, the fact that it is speeding up its spin is very strange. There is a way neutron stars or white dwarfs can increase their spin speed, or "spin up" after their birth. It depends on whether they have a close companion star. As such, the new study's team suspects CHIME J1634+44 may actually be composed of two stellar objects orbiting each other in a tight binary format. The ASTRON team proposes that this companion is either another stellar remnant (like a white dwarf or neutron star) or is a "failed star" brown dwarf — a body that forms like a star but fails to gather enough mass to trigger the nuclear fusion that defines what a star is. As these bodies swirl around each other, they would emit ripples in spacetime called gravitational waves. This carries away angular momentum and causes the two stellar bodies to move closer together. This would cause the period of the binary to appear as if it is shortening. This type of orbital tightening has been witnessed before by astronomers in white dwarf binaries. CHIME J1634+44 gets stranger, however. Its radio bursts are 100% circularly polarized. This means the electromagnetic waves escaping J1634+44 rotate in a circle (like a corkscrew) as they propagate. Thus, the electromagnetic radiation escaping CHIME J1634+44 twists around in a perfect spiral as it moves away from its source. Not only is that extremely rare, but it is something that has never been seen in bursts of radiation from either neutron stars or white dwarfs. That implies the radio wave blasts of CHIME J1634+44 are being generated in a way that is unique for this dead star. Astronomers have a mystery on their hands with this dead star What is also weird about these pulses is the fact that they arrive in pairs, but only when the dead star in the CHIME J1634+44 binary has spun several times without emitting a burst. "The time between pulse pairs seems to follow a choreographed pattern," team member and ASTRON astronomer Harish Vedantham said in a statement. "We think the pattern holds crucial information about how the companion triggers the white dwarf to emit radio waves. "Continued monitoring should help us decode this behavior, but for now, we have a real mystery on our hands." Related Stories: — New kind of pulsar may explain how mysterious 'black widow' systems evolve — Hear 'black widow' pulsar's song as it destroys companion —NASA X-ray spacecraft reveals secrets of a powerful, spinning neutron star The research conducted by these astronomers not only reveals more about neutron stars, the universe's most extreme stellar objects, but also hints at an exciting new phase for radio astronomy. "The discovery of CHIME J1634+44 expands the known population of LPTs and challenges existing models of neutron stars and white dwarfs, suggesting there may be many more such objects awaiting discovery," Dong concluded. Both teams' research was published on Thursday (July 17) in the journal Astronomy & Astrophysics. Solve the daily Crossword
Yahoo
04-07-2025
- Science
- Yahoo
Giant radio telescope in the Utah desert could reveal hidden corners of the cosmos — and brand-new physics
When you buy through links on our articles, Future and its syndication partners may earn a commission. A gigantic array of radio dishes proposed for the Utah desert could advance our understanding of physics and help us decode cosmic radio signals. Now, scientists have outlined how it would work. Beginning in the 1950s, radio astronomy has opened up a powerful view into the inner workings of the universe, revealing everything from how stars form to incredible images of our galaxy's gigantic black hole. Now, astronomers are building a gigantic array of radio dishes, called the Deep Synoptic Array 2000 (DSA-2000). The array consists of 2,000 radio dishes, each 16 feet (5 meters) across, laid out in a radio-quiet part of the Utah desert. Now, an international team of astronomers has demonstrated how DSA-2000 will be a premier instrument for revealing some of the most hidden corners, particles and processes in the cosmos. Because DSA-2000 will have both a wide field of view and a high resolution, it will be like the world's ultimate digital camera but at radio frequencies, the team explained in a paper uploaded to the preprint database arXiv in May. These capabilities will allow the DSA-2000 to detect a wide variety of phenomena that are not possible with our current radio telescopes. And there are a whole lot of unexplored radio transmissions in the universe. For example, astronomers think the vast majority of the mass of every galaxy comes in the form of dark matter, an invisible entity that has so far escaped direct detection. One potential candidate for dark matter is called the axion, a hypothetical particle trillions of times lighter than the lightest known particles. Axions can collect around dense objects like neutron stars, and under the influence of extremely strong magnetic fields (which neutron stars have in spades), they can convert to photons with just the right frequency range that DSA-2000 could pick up those signals. Related: 'Staggering' first images from Vera C. Rubin Observatory show 10 million galaxies — and billions more are on the way Another candidate for dark matter is called the dark photon, which is like our normal, familiar photons (light particles) but … dark. Dark photons can also collect around neutron stars, where they can get whipped up into a frenzy due to the star's extreme rotation. In a process called superradiance, the dark photons get boosted to extremely high energies, where they start to resonate with regular photons, giving off blasts of signals that could be directly detected by DSA-2000. This means that DSA-2000 could potentially offer our first direct glimpse of a new form of matter in the universe. But that's not all. In 2023, astronomers with the NANOGrav experiment announced the detection of gravitational waves through pulsar timing arrays. DSA-2000 could take that one step further by precisely measuring the rotation rates of approximately 3,000 pulsars — rapidly spinning neutron stars that pulsate in regular intervals. This would allow the new instrument to find any subtle variations in the spins of pulsars, such as those due to unseen orbiting companions, like black holes or small clumps of dark matter. RELATED STORIES —James Webb telescope unveils largest-ever map of the universe, spanning over 13 billion years —What if the Big Bang wasn't the beginning? New research suggests it may have taken place inside a black hole —Catastrophic collision between Milky Way and Andromeda galaxies may not happen after all, new study hints Lastly, DSA-2000 could detect tens of thousands of fast radio bursts (FRBs) — tremendous explosions that manifest as blips and bloops in the radio spectrum. This unprecedented number of detections would allow scientists to build a comprehensive survey of the nearby universe, which would aid our understanding of everything from dark energy to the nature of ghostly particles called neutrinos. The universe is trying to whisper its secrets to us. All the answers are there, if we listen carefully enough.
Yahoo
01-07-2025
- Science
- Yahoo
Long-dead satellite emits strong radio signal, puzzling astronomers
Astronomers in Australia picked up a strange radio signal in June 2024 — one near our planet and so powerful that, for a moment, it outshined everything else in the sky. The ensuing search for its source has sparked new questions around the growing problem of debris in Earth's orbit. At first, though, the researchers thought they were observing something exotic. 'We got all excited, thinking we had discovered an unknown object in the vicinity of the Earth,' said Clancy James, an associate professor at Curtin University's Curtin Institute of Radio Astronomy in Western Australia. The data James and his colleagues were looking at came from the ASKAP radio telescope, an array of 36 dish antennas in Wajarri Yamaji Country, each about three stories tall. Normally, the team would be searching the data for a type of signal called a 'fast radio burst' — a flash of energy blasting forth from distant galaxies. 'These are incredibly powerful explosions in radio (waves) that last about a millisecond,' James said. 'We don't know what's producing them, and we're trying to find out, because they really challenge known physics — they're so bright. We're also trying to use them to study the distribution of matter in the universe.' Astronomers believe these bursts may come from magnetars, according to James. These objects are very dense remnants of dead stars with powerful magnetic fields. 'Magnetars are utterly, utterly insane,' James said. 'They're the most extreme things you can get in the universe before something turns into a black hole.' But the signal seemed to be coming from very close to Earth — so close that it couldn't be an astronomical object. 'We were able to work out it came from about 4,500 kilometers (2,800 miles) away. And we got a pretty exact match for this old satellite called Relay 2 — there are databases that you can look up to work out where any given satellite should be, and there were no other satellites anywhere near,' James said. 'We were all kind of disappointed at that, but we thought, 'Hang on a second. What actually produced this anyway?'' NASA launched Relay 2, an experimental communications satellite, into orbit in 1964. It was an updated version of Relay 1, which lifted off two years earlier and was used to relay signals between the US and Europe and broadcast the 1964 Summer Olympics in Tokyo. Just three years later, with its mission concluded and both of its main instruments out of order, Relay 2 had already turned into space junk. It has since been aimlessly orbiting our planet, until James and his colleagues linked it to the weird signal they detected last year. But could a dead satellite suddenly come back to life after decades of silence? To try to answer that question, the astronomers wrote a paper on their analysis, set to publish Monday in the journal The Astrophysical Journal Letters. They realized the source of the signal wasn't a distant galactic anomaly, but something close by, when they saw that the image rendered by the telescope — a graphical representation of the data — was blurry. '(T)he reason we were getting this blurred image was because (the source) was in the near field of the antenna — within a few tens of thousands of kilometers,' James said. 'When you have a source that's close to the antenna, it arrives a bit later on the outer antennas, and it generates a curved wave front, as opposed to a flat one when it's really far away.' This mismatch in the data between the different antennas caused the blur, so to remove it, the researchers eliminated the signal coming from the outer antennas to favor only the inner part of the telescope, which is spread out over about 2.3 square miles in the Australian outback. 'When we first detected it, it looked fairly weak. But when we zoomed in, it got brighter and brighter. The whole signal is about 30 nanoseconds, or 30 billionths of a second, but the main part is just about three nanoseconds, and that's actually at the limit of what our instrument can see,' James said. 'The signal was about 2,000 or 3,000 times brighter than all the other radio data our (instrument) detects — it was by far the brightest thing in the sky, by a factor of thousands.' The researchers have two ideas on what could have caused such a powerful spark. The main culprit was likely a buildup of static electricity on the satellite's metal skin, which was suddenly released, James said. 'You start with a buildup of electrons on the surface of the spacecraft. The spacecraft starts charging up because of the buildup of electrons. And it keeps charging up until there's enough of a charge that it short-circuits some component of the spacecraft, and you get a sudden spark,' he explained. 'It's exactly the same as when you rub your feet on the carpet and you then spark your friend with your finger.' A less likely cause is the impact of a micrometeorite, a space rock no bigger than 1 millimeter (0.039 inches) in size: 'A micrometeorite impacting a spacecraft (while) traveling at 20 kilometers per second or higher will basically turn the (resulting) debris from the impact into a plasma — an incredibly hot, dense gas,' James said. 'And this plasma can emit a short burst of radio waves.' However, strict circumstances would need to come into play for this micrometeorite interaction to occur, suggesting there's a smaller chance it was the cause, according to the research. 'We do know that (electrostatic) discharges can actually be quite common,' James said. 'As far as humans are concerned, they're not dangerous at all. However, they absolutely can damage a spacecraft.' Because these discharges are difficult to monitor, James believes the radio signal event shows that ground-based radio observations could reveal 'weird things happening to satellites' — and that researchers could employ a much cheaper, easier-to-build device to search for similar events, rather than the sprawling telescope they used. He also speculated that because Relay 2 was an early satellite, it might be that the materials it's made of are more prone to a buildup of static charge than modern satellites, which have been designed with this problem in mind. But the realization that satellites can interfere with galactic observations also presents a challenge and adds to the list of threats posed by space junk. Since the dawn of the Space Age, almost 22,000 satellites have reached orbit, and a little more than half are still functioning. Over the decades, dead satellites have collided hundreds of times, creating a thick field of debris and spawning millions of tiny fragments that orbit at speeds of up to 18,000 miles per hour. 'We are trying to see basically nanosecond bursts of stuff coming at us from the universe, and if satellites can produce this as well, then we're going to have to be really careful,' James said, referring to the possibility of confusing satellite bursts with astronomical objects. 'As more and more satellites go up, that's going to make this kind of experiment more difficult.' James and his team's analysis of this event is 'comprehensive and sensible,' according to James Cordes, Cornell University's George Feldstein Professor of Astronomy, who was not involved with the study. 'Given that the electrostatic discharge phenomenon has been known for a long time,' he wrote in an email to CNN, 'I think their interpretation is probably right. I'm not sure that the micrometeoroid idea, pitched in the paper as an alternative, is mutually exclusive. The latter could trigger the former.' Ralph Spencer, Professor Emeritus of Radio Astronomy at the University of Manchester in the UK, who was also not involved with the work, agrees that the proposed mechanism is feasible, noting that spark discharges from GPS satellites have been detected before. The study illustrates how astronomers must take care to not confuse radio bursts from astrophysical sources with electrostatic discharges or micrometeoroid bursts, both Cordes and Spencer pointed out. 'The results show that such narrow pulses from space may be more common than previously thought, and that careful analysis is needed to show that the radiation comes from stars and other astronomical objects rather than man-made objects close to the Earth,' Spencer added in an email. 'New experiments now in development, such as the Square Kilometre array Low frequency array (SKA-Low) being built in Australia, will be able to shed light on this new effect.' Clarification: This story has been updated to clarify the time frame in which the strange radio signal was detected.
