Astronomers spot the fastest star in the galaxy
Arapidly twirling, ultramagnetic 500-year-old baby neutron star has been spotted zipping at never-beforeseen speeds through the Milky Way. The flickering X-rays and radio waves of this giant baby, adorably named J1818.0-1607, would likely have first appeared in the sky when Nicolaus Copernicus, the Polish scientist who proposed that the Sun, and not Earth, was the centre of the universe, first looked up at the heavens. If Copernicus had orbital X-ray telescopes or powerful radio receivers, he would have witnessed the birth of a magnetar: a superrare, violent species of neutron star with extreme, twisted-up magnetic fields. A mere 500 years later – assuming astronomers got its age right – this screaming infant is still spinning faster than any known magnetar, at one revolution every 1.4 seconds. It may also be moving faster than any previously discovered neutron star of any variety. Like all neutron stars, J1818.0-1607 would have emerged after the explosive death of a large star, known as a supernova, as the crushed remnant of its core. Neutron stars are tiny in astrophysical terms, typically just 12 miles in diameter. But as the densest known objects in the universe other than black holes – full of matter crushed to the point of atoms losing their structural integrity and mushing together to resemble the nucleus of a single giant atom – neutron stars can be as massive as full-size stars. Only a minuscule fraction of neutron stars are magnetars. But that isn’t the only unusual thing about J1818.0-1607. It’s also a pulsar, a type of ultrafast, cosmic lighthouse that dims and brightens with each rotation. “Only five magnetars, including this one, have been recorded to also act like pulsars, constituting less than 0.2 per cent of the known neutron star population,” said researchers. To determine the age of the magnetar, the researchers tracked how it slowed over time and estimated the spin rate it was born with. From its starting rotational speed, it would have taken 500 years for the newborn magnetar to slow to its current rate. However, this age estimate is somewhat unreliable. Because the magnetar is so young, astronomers should be able to spot the remnant of the supernova that birthed it, and the researchers may have found it a ‘relatively large’ distance from the magnetar. If the magnetar really is 500 years old and that supernova remnant really is the leftovers of the magnetar’s birth, then it’s been moving about 8 to 16 million miles per hour through the Milky Way for its entire lifetime, faster than any of the approximately 3,000 other known neutron stars. If, however, astronomers estimated the wrong age for the magnetar, or the researchers identified the wrong remnant, then this youngster may not be moving quite so fast. But although this baby is a newborn in astronomical terms, there may be an even younger magnetar in the Milky Way, though perhaps a slower moving one. Researchers think they may have witnessed the actual birth of a magnetar in a distant galaxy last year, making that newfound magnetar no older than a human toddler.