Latest news with #NandaRea
Time Magazine
3 days ago
- Science
- Time Magazine
Scientists Are Stumped by Mysterious Pulsing ‘Star'
Something strange is going on 15,000 light years from Earth. Out at that distant remove, somewhere in the constellation Scutum, an unexplained body is semaphoring into space, blinking in both X-ray and radio frequencies once every 44 minutes in a way never seen by astronomers before. The object could be a white dwarf —an Earth-sized husk that remains after a star has exhausted its nuclear fuel. Or not. It could also be a magnetar —a neutron star with an exceedingly powerful magnetic field. Unless it's not that either. 'Astronomers have looked at countless stars with all kinds of telescopes and we've never seen one that acts this way,' said astronomer Ziteng Wang of Curtin University in Australia, in a statement that accompanied the May 28 release of a paper in Nature describing the object, for which he was lead author. 'It's thrilling to see a new type of behavior for stars.' So what exactly is the mysterious body—which goes by the technical handle ASKAP J1832—and how common is this species of object? ASKAP J1832 is by no means unique in the universe in sending out energy in steady flashes. Pulsars —rapidly spinning neutron stars—do too. But pulsars flash much faster than ASKAP J1832 does, on the order of milliseconds to seconds. In 2022, astronomers discovered a type of object known as a long-period transient, which, like ASKAP J1832, sends out flashes of radio waves on the order of tens of minutes. So far 10 such bodies have been found, but none identical to ASKAP J1832, which is the first to emit X-rays too. What's more, ASKAP J1832's emissions have changed over time. During one observation with NASA's orbiting Chandra X-Ray Observatory in February 2024, the object was prodigiously producing both X-rays and radio waves. During a follow-up observation six months later, the radio waves were 1,000 times fainter and no X-rays were detected. That was a puzzle. 'We looked at several different possibilities involving neutron stars and white dwarfs, either in isolation or with companion stars,' said co-author Nanda Rea of the Institute of Space Sciences in Barcelona, Spain, in a statement. 'So far nothing exactly matches up, but some ideas work better than others.' One of those ideas is the magnetar, but that doesn't fit precisely, due to ASKAP J1832's bright and variable radio emissions. The white dwarf remains a possibility, however in order to produce the amount of energy it does, ASKAP J1832 would have to be orbiting another body in a formation known as a binary system, and so far that second body hasn't been detected. Viewed from Earth, ASKAP J1832 appears to be located in a supernova remnant, a cloud of hot gas and high energy particles that remains after an aging star meets its explosive end. But the authors of the paper concluded that the remnant merely lies in the foreground of the observational field with ASKAP J1832 in the background, the way an earthly cloud can drift in the path of the sun. So for now, the object remains a riddle—one that will be investigated further. 'Finding a mystery like this isn't frustrating,' said co-author Tong Bao of the Italian National Institute for Astrophysics, in a statement. 'It's what makes science exciting.'
Observer
3 days ago
- Science
- Observer
Astronomers scrutinise a star behaving unlike any other
WASHINGTON: Astronomers have spotted a star acting unlike any other ever observed as it unleashes a curious combination of radio waves and X-rays, pegging it as an exotic member of a class of celestial objects first identified only three years ago. It is located in the Milky Way galaxy about 15,000 light-years from Earth in the direction of the constellation Scutum, flashing every 44 minutes in both radio waves and X-ray emissions. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km). The researchers said it belongs to a class of objects called "long-period radio transients", known for bright bursts of radio waves that appear every few minutes to several hours. This is much longer than the rapid pulses in radio waves typically detected from pulsars - a type of speedily rotating neutron star, the dense collapsed core of a massive star after its death. Pulsars appear, as viewed from Earth, to be blinking on and off on timescales of milliseconds to seconds. "What these objects are and how they generate their unusual signals remain a mystery," said astronomer Ziteng Wang of Curtin University in Australia, lead author of the study published this week in the journal Nature. In the new study, the researchers used data from Nasa's orbiting Chandra X-ray Observatory, the ASKAP telescope in Australia and other telescopes. While the emission of radio waves from the newly identified object is similar to the approximately 10 other known examples of this class, it is the only one sending out X-rays, according to astrophysicist and study co-author Nanda Rea of the Institute of Space Sciences in Barcelona. The researchers have some hypotheses about the nature of this star. They said it may be a magnetar, a spinning neutron star with an extreme magnetic field, or perhaps a white dwarf, a highly compact stellar ember, with a close and quick orbit around a small companion star in what is called a binary system. "However, neither of them could explain all observational features we saw," Wang said. Stars with up to eight times the mass of our sun appear destined to end up as a white dwarf. They eventually burn up all the hydrogen they use as fuel. Gravity then causes them to collapse and blow off their outer layers in a "red giant" stage, eventually leaving behind a compact core roughly the diameter of Earth - the white dwarf. The observed radio waves potentially could have been generated by the interaction between the white dwarf and the hypothesised companion star, the researchers said. - Reuters
The Independent
25-04-2025
- Science
- The Independent
Nasa tracks runaway ‘zombie star' capable of ripping humans apart
Nasa is tracking a potentially devastating 'zombie star' as it races through our galaxy at more than 177,000 km/h (110,000 mph). The immensely dense object is one of 30 known magnetars in the Milky Way, which are the dead remnants of stars composed entirely of neutrons. Measuring just 20 kilometres across, Magnetar SGR 0501+4516 holds more mass than the Sun and has a magnetic field that is about a trillion times more powerful than Earth's magnetosphere. The magnetar was discovered by researchers using the Hubble Space Telescope, with Nasa describing the 'runaway' object as having 'comic-book-hero superpowers'. In a blog post detailing the finding, Nasa's Hubble Mission team noted that the magnetar originated from an unknown part of the universe, but may offer insights into some of its biggest mysteries. 'If a human got within 600 miles, the magnetar would become a proverbial sci-fi death-ray, ripping apart every atom inside the body,' the team wrote. 'This runaway magnetar is the likeliest candidate in our Milky Way galaxy for a magnetar that was not born in a supernova explosion as initially predicted. It is so strange it might even offer clues to the mechanism behind events known as fast radio bursts.' Astronomers previously thought that Magnetar SGR 0501+4516 was born from a core-collapse of a neighbouring supernova, however new observations have cast doubt on its birthplace. The revelation means the magnetar must be either far older than its reported 20,000-year age, or it formed through the merger of two neuron stars. 'Magnetars are neutron stars – the dead remnants of stars – composed entirely of neutrons,' said Ashley Chrimes, who led the team who made the discovery. 'What makes magnetars unique is their extreme magnetic fields, billions of times stronger than the strongest magnets we have on Earth.' Nanda Rea of the Institute of Space Sciences in Barcelona, Spain, added: 'Magnetar birth rates and formation scenarios are among the most pressing questions in high-energy astrophysics, with implications for many of the universe's most powerful transient events, such as gamma-ray bursts, superluminous supernovae, and fast radio bursts.' The research team will continue to observe the magnetar in an effort to better understand its path through the Milky Way and its origins.
