Astronomers discover unique star blasting its radio wave beam in odd directions
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The magnetar Swift J1818.0–1607 is only about 240 years old, a veritable newborn by cosmic standards as per a study published in the journal Astrophysical Journal Letters
Scientists have discovered a unique star flipping its polarity and blasting its radio wave beam in odd directions around 15,000 light-years away.
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.
"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.
The magnetar Swift J1818.0–1607 is only about 240 years old, a veritable newborn by cosmic standards as per a study published in the journal Astrophysical Journal Letters.
Magnetars are a type of neutron star, an incredibly dense object mainly made up of tightly packed neutrons, which forms from the collapsed core of a massive star during a supernova.
Magnetars differ from other neutron stars is that they also have the most powerful known magnetic fields in the Universe.
"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 the 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 behaviours 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.
Other astronomers have also observed J1818.0-1607 with radio telescopes, such as the NSF's Karl Jansky Very Large Array (VLA), and determined that it gives off radio waves. This implies that it also has properties similar to that of a typical "rotation-powered pulsar," a type of neutron star that gives off beams of radiation that are detected as repeating pulses of emission as it rotates and slows down.
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.