Magnetars are the strongest magnets in the universe!
13,000 light-years away in the constellation Scutum, near the center of our Milky Way galaxy, astronomers discovered an enormous cloud of high-energy particles, known as a wind nebula, circling around a rare ultra-magnetic neutron star, or magnetar — the strongest magnets in the universe.
A neutron star is what’s left over after a massive star runs out of fuel. The star collapses under its own weight and then explodes as a supernova, leaving behind neutrons packed tightly together. This compactness means neutron stars are extremely dense, with masses of half a million Earth’s compressed into a ball just 20 kilometers (12 miles) across — roughly the length of New York’s Manhattan Island (seen below).
Illustration comparing the size of a neutron star to Manhattan Island in New York, which is about 13 miles long. Photo credit: NASA's Goddard Space Flight Center
Neutron stars are most often observed as pulsars, which produce radio, visible light, X-rays, and gamma rays in different regions of their magnetic fields. Typical pulsar magnetic fields can be 100 billion to 10 trillion times stronger than Earth’s, while magnetar fields are often a thousand times stronger still. However, scientists don’t know how magnetars are created. Of the 2,600 neutron stars known, only 29 are classified as magnetars.
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The magnetar, named Swift J1834.9-0846, was discovered by NASA’s Swift satellite. It is so rare because it is the first one discovered that is surrounded by a wind nebula. The nebula is centered across the magnetar and spans 15 light-years.
X-ray imaging showing wind nebula emission around Swift J1834.9-0846. Photo credit: ESA/XMM-Newton/Younes et al. 2016
“Right now, we don’t know how J1834.9 developed and continues to maintain a wind nebula, which until now was a structure only seen around young pulsars,” said lead researcher George Younes, a postdoctoral researcher at George Washington University, in a NASA news release.
Co-author Chryssa Kouveliotou, a professor in the Department of Physics at George Washington University’s Columbian College of Arts and Sciences, said, “For me the most interesting question is, why is this the only magnetar with a nebula? Once we know the answer, we might be able to understand what makes a magnetar and what makes an ordinary pulsar.”
A paper describing the discovery is currently available online on arXiv.org, and the peer-reviewed version will be published in the The Astrophysical Journal.
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