Dead star found to be hiding strongest magnet in the universe

Artist's impression of SGR 0148 (courtesy: ESA/ATG Medialab)

Monday, August 19, 2013, 5:26 PM -

Scientists at the European Space Agency have made a curious discovery about a dead neutron star.

Once thought to have an unusually low magnetic field, it appears to be hiding one of the strongest magnets in the universe -- trillions of times greater than those found on Earth.

The star, called SGR 0418+5729 -- or SGR 0418 for short -- is 6,500 light years from Earth.

Its mass is greater than our Sun, but it is incredibly small, measuring only 20 km across.

Scientists are calling the star a magnetar -- a neutron star with an extremely powerful magnetic field.

SGR 0418 was detected in June 2009, and scientists have been studying it ever since.

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"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,” said Andrea Tiengo, lead author of the paper, in a statement.

"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."

Normally, scientists determine the magnetic field of a magnetar by measuring the rate at which the star's spin is declining, but for SGR 0148, researchers searched for variations in the X-ray spectrum of the magnetar over short time intervals. 

"This method allows astronomers to analyse the magnetic field in much more detail and has revealed SGR 0418 as a true magnetic monster," ESA writes.

The full paper has been published in Nature magazine.