Astronomers recently discovered remarkable neutron star known as Swift J1818.0−1607. A new study estimates that it is only about 240 years old — a veritable newborn by cosmic standards. NASA’s Neil Gehrels Swift Observatory spotted the young object on March 12, when it released a massive burst of X-rays. Follow-up studies by the European Space Agency’s XMM-Newton observatory and NASA’s NuSTAR telescope, which is led by Caltech and managed by the agency’s Jet Propulsion Laboratory, revealed more of the neutron star’s physical characteristics, including those used to estimate its age.
With a magnetic field up to 1,000 times stronger than a typical neutron star — and about 100 million times stronger than the most powerful magnets made by humans — Swift J1818.0−1607 belongs to a special class of objects called magnetars, which are the most magnetic objects in the universe. And it appears to be the youngest magnetar ever discovered. If its age is confirmed, that means light from the stellar explosion that formed it would have reached Earth around the time that George Washington became the first president of the United States.
“This object is showing us an earlier time in a magnetar’s life than we’ve ever seen before, very shortly after its formation,” said Nanda Rea, a researcher at the Institute of Space Sciences in Barcelona and principal investigator on the observation campaigns by XMM Newton and NuSTAR (short for Nuclear Spectroscopic Telescope Array).
While there are over 3,000 known neutron stars, scientists have identified just 31 confirmed magnetars — including this newest entry. Because their physical properties can’t be re-created on Earth, neutron stars (including magnetars) are natural laboratories for testing our understanding of the physical world.
“Maybe if we understand the formation story of these objects, we’ll understand why there is such a huge difference between the number of magnetars we’ve found and the total number of known neutron stars,” Rea said.
Swift J1818.0−1607 is located in the constellation Sagittarius and is relatively close to Earth — only about 16,000 light-years away. (Because light takes time to travel these cosmic distances, we are seeing light that the neutron star emitted about 16,000 years ago, when it was about 240 years old.) Many scientific models suggest that the physical properties and behaviors of magnetars change as they age and that magnetars may be most active when they are younger. So finding a younger sample close by like this will help refine those models.
Source: “A cosmic baby is discovered, and it’s brilliant” NASA, 17 June 2020. <https://www.nasa.gov/feature/jpl/a-cosmic-baby-is-discovered-and-its-brilliant>