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Making a Magnetar

August 6, 2015

Magnetars are the strongest magnets in the universe. Their magnetic fields are more than a million billion times stronger than Earth’s. And astronomers recently found that a star cluster may have given birth to a magnetar, providing important clues about how these giant magnets form.

Astronomers observed an odd blue star near a cluster in Ara, a constellation that’s visible from the far-southern United States, just below the tail of Scorpius.

The star is unusual for a couple of reasons. First, it’s racing away from the star cluster. And second, its surface has a lot of carbon.

The star cluster has one of the few known magnetars. So the astronomers suggest that the blue star and the magnetar once formed a binary, with the two stars orbiting each other. At the time, the magnetar was a fairly normal star, albeit a massive one.

But the blue star dumped some of its gas onto its mate. That caused the companion to spin faster, which boosted its magnetic field. Then the rapidly spinning star exploded as a supernova, spraying carbon onto the blue star and kicking it out of the cluster. Because of its fast spin, the tiny but heavy corpse of the exploding star became a magnetar.

If this idea is right, then at least some magnetars owe their extraordinary properties to former companions. Such a scenario doesn’t happen often, though, so magnetars are rare; to date, astronomers have cataloged only a couple of dozen of them.

Script by Ken Croswell, Copyright 2015

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