Magnetars: City-Sized Magnets Born from Dying Stars

Magnetars are the highly magnetic corpses of massive stars. Recent observations show magnetars cause the mysterious Fast Radio Burst signals that astronomers have detected for more than a decade.

By Eric Betz
Nov 6, 2020 3:00 PM
Magnetar - NASA
Astronomers believe FRBs are associated with magnetars, which are the highly magnetic remnants of massive stars. (Credit: NASA/Goddard Space Flight Center)

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Magnetars, short for “magnetic stars,” are ultra-dense corpses of dead stars surrounded by intense magnetic fields. And according to new research, magnetars also appear to be the cause of at least some mysterious fast radio bursts, or FRBs, which astronomers have detected for more than a decade. So, by studying FRBs, scientists think they might be able to peel back the onion on magnetars.

What is a Magnetar? 

When a massive star exhausts its nuclear fuel, it will often die in dramatic fashion, exploding as a supernova. The star’s outer layers erupt into space, and its core collapses into an extremely dense new object called a neutron star. These stellar corpses are mind-bogglingly dense. Most neutron stars are roughly 14 miles (23 kilometers) across, despite weighing more than our sun. You can think of them as a single atomic nucleus scaled up to the size of a city, astronomers say.

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