Neutron stars are one of the end products of supernovae, the explosive death some massive stars experience. They are extremely dense and have incredible properties. It's thought the collision of two new neutron stars 4.6 billion years ago provided our Solar System with many of its heavy elements, 100 million years before Earth formed. Now, astronomers have announced the discovery of a new neutron star, and they were incredibly surprised to discover that it was only 240 years old. In cosmic terms, a bright new baby.
The object is called Swift J1818.0-1607 and is located 16,000 light-years from Earth. It's twice the mass of the Sun in a sphere less than 30 kilometers (20 miles) in diameter and spins on its axis every 1.36 seconds. It's now one of 3,000 known neutron stars, but even among these objects, it is a special case. Swift J1818.0-1607 is classified as a magnetar, a neutron star with an incredible magnetic field. And that’s no exaggeration.
It has a magnetic field up to 1,000 times stronger than the average neutron star, or about 100 million times stronger than the strongest magnet created by humans. Only 31 magnetars are known in the universe. Catching one in its infancy is an incredible find as their properties are believed to change with age. The research describing the cosmic infant is published in The Astrophysical Journal Letters.
"This object is showing us an earlier time in a magnetar's life than we've ever seen before, very shortly after its formation," co-author Nanda Rea, a researcher at the Institute of Space Sciences in Barcelona said in a statement. "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."
The star was spotted by NASA's Neil Gehrels Swift Observatory on March 12 this year, when Swift J1818.0-1607 had a sudden outburst of X-rays, which made it 10 times brighter than normal. This was followed up by the European Space Agency's XMM-Newton observatory and NASA's NuSTAR telescope. If its scarce magnetar status and its surprising youth weren’t enough, this object has another rare characteristic. It is one of five magnetars that emit a long-lived radio beam, also known as radio pulsars. In fact, Swift J1818.0-1607 is the youngest pulsar ever observed.
"What's amazing about [magnetars] is they're quite diverse as a population," said Victoria Kaspi, director of the McGill Space Institute at McGill University in Montreal and a former member of the NuSTAR team, who was not involved with the study. "Each time you find one it's telling you a different story. They're very strange and very rare, and I don't think we've seen the full range of possibilities."