The Mysterious Magnetar With an Insanely Strong Magnetic Field

By Jamie Condliffe on at

A team of scientists using the European Space Agency's XMM-Newton space telescope have discovered a weird dead star , which hides one of the strongest magnetic fields in the Universe.

The magnetar—a particular kind of neutron star—is called SGR 0418+5729, and is essentially the dead core of a once massive star that collapsed in on itself. It's extremely dense, packing more than the mass of our Sun into a sphere only just 20 km across, and turns out to have a magnetic fields billions to trillions of times greater than those generated in hospital MRI machines. Andrea Tiengo, one of the researchers, explains:

“Until very recently, all indications were that this magnetar had one of the weakest surface magnetic fields known; at 6 x 1012 Gauss, it was roughly a 100 times lower than for typical magnetars. Understanding these results was a challenge. However, we suspected that SGR 0418 was in fact hiding a much stronger magnetic field, out of reach of our usual analytical techniques. To explain our observations, this magnetar must have a super-strong, twisted magnetic field reaching 1015 Gauss across small regions on the surface, spanning only a few hundred metres across. On average, the field can appear fairly weak, as earlier results have suggested. But we are now able to probe sub-structure on the surface and see that the field is very strong locally.”

You can think of the strong, localised magnetic fields a bit like sunspots—but instead of producing a flare, they produce bursts of X-rays. And, you know, look quite pretty in the picture, too. [ESA]